Question Bank in DC Circuits

Question Bank in DC Circuits A. DC CIRCUITS: BASIC PRINCIPLES 1. REE Board Exam March 1998 The substation bus bar is made up of 2 inches round copper bars 20 ft long. What is the resistance of each bar if resistivity is 1.724 x 10-6 ohm-cm. A. 7.21 x 10-5 Ω C. 5.185 x 10-5 Ω B. 13.8 x 10-6 Ω D. 2.96 x 10-5 Ω 2. REE October 1997 Determine the resistance of a busbar made of copper if the length is 10 meters long and the cross section is a 4 x 4 cm 2. Use 1.7241 micro ohm-cm as the resistivity. A. 2.121 x 10-4 Ω C. 3.431 x 10-5 Ω B. 4.312 x 10-4 Ω D. 1.078 x 10-4 Ω 3. EE Board Exam October 1991 One turn of a copper bar is produced by cutting copper washer along a radius and spreading the ends. The washer is cut from soft drawn copper having a resistivity at 20°C of 1.732 x 10-6 ohm-cm. The washer is 0.125 inch thick and has inside diameter and outside diameter of 1 inch and 9 inches respectively. Calculate the exact resistance between the two ends of the turn to direct current, taking into account the non-uniform current distribution. Assume the contact along the ends of the turn to be perfect over the entire cross section. A. 12.74 x 10-6 Ω C. 17.22 x 10-6 Ω B. 15.53 x 10-6 Ω D. 14.83 x 10-6 Ω 4. EE Board Exam October 1990 Determine the resistance of a conductor 0.10 m long, with a uniform diameter of 1.0 cm and having a resistivity which varies as a function of length L measured from the one end of the conductor according to ρ = 0.003 + 10-4 L2 ohm-cm. A. 0.0852 ohm C. 0.0806 ohm B. 0.0915 ohm D. 0.0902 ohm 5. EE Board Exam April 1992 A coil has 6,000 turns of wire and a resistance of 380 ohms. The coil is rewound with the same quantity (weight) of wire, but has 13,400 turns. How many ohms will the new coil have?

A. 1895 ohms B. 1825 ohms

C. 1792 ohms D. 1905 ohms

6. EE Board Exam April 1992 A copper wire of unknown length has a resistance of 0.80 ohm. By successive passes through drawing dies, the length of the wire is increased by 2 ½ times its original value. Assuming that resistivity remains unchanged during the drawing process, determine the new value of its resistance. A. 4 ohms C. 5 ohms B. 3 ohms D. 6 ohms

7. REE Board Exam October 1998 A one-meter rod of 2-cm diameter is drawn until its resistance is 100 times the initial resistance. Its length afterwards is? A. 10 m C. 12.5 m B. 100 m D. 5 m 8. EE Board Exam April 1993 A kilometer of wire having a diameter of 11.7 mm and a resistance of 0.031 ohm is drawn down so that its diameter is 5.0 mm. What does its resistance become? A. 0.85 ohm C. 0.93 ohm B. 0.78 ohm D. 0.81 ohm 9. EE Board Exam April 1995 A certain wire has a resistance R. The resistance of another wire identical with the first except for having twice its diameter is A. 4R C. 2R B. R/2 D. R/4 10. REE Board Exam October 1996 What is the size in square millimeter (mm 2) is the cable of 250 MCM size? A. 118.656 mm2 C. 112.565 mm2 B. 126.675 mm2 D. 132.348 mm2 11. REE Board Exam October 1998, September 2001 The resistance of a copper wire at 30°C is 50 ohms. If the temperature coefficient of copper at 0°C is 0.00427, what is the resistance at 100°C? A. 72.26 ohms C. 63.24 ohms

B. 54.25 ohms

D. 58.15 ohms

12. REE Board Exam March 1998 The resistance of a wire is 126.48 Ω at 100°C and 100 Ω at 30°C. Determine the temperature coefficient of copper at 0°C. A. 0.00427/°C C. 0.0256/°C B. 0.00615/°C D. 0.365/°C 13. EE Board Exam October 1991 Two heating elements which is 500 ohms and 250 ohms are connected in series with temperature coefficients of 0.001 and 0.003 ohms per °C, respectively at 20°C. Calculate the effective temperature coefficient of the combination. A. 0.00215 C. 0.00712 B. 0.00626 D. 0.00167 14. EE Board Exam October 1992 The insulation resistance of a kilometer of the cable having a diameter of 2 cm and an insulation thickness of 2 cm is 600 ohms. If the thickness of the insulation is increased to 3 cm, find the insulation resistance of the cable. A, 725 ohms C. 757 ohms B. 850 ohms D. 828 ohms 15. EE Board Exam April 1989 It is required that a loading of 3 kW be maintained in a heating element at an initial temperature of 20°C, a voltage of 220 V is necessary for the purpose. After the element has settled down to steady state, it is found that a voltage of 240 volts is necessary to maintain the 3 kW loading. The element resistance temperature coefficient is 0.0006 per degree centigrade at 20°C. Calculate the final temperature of the heating element. A. 345.43°C C. 336.84°C B. 326.42°C D. 318.48°C 16. REE Board Exam October 1999 How long must a current of 5 A pass through a 10 ohm resistor until a charge of 12000 coulomb passes through? A. 1 min C. 3 min B. 2 min D. 4 min

What is the power required to transfer 97,000 coulombs of charge through a potential rise of 50 volts in one hour? A. 0.5 kW C. 1.3 kW B. 0.9 kW D. 2.8 kW 18. REE Board Exam April 2001 A round wire has 250 MCM. Find its diameter in inches. A. ½ C. 0.16 B. ¼ D. 0.08 19. REE Board Exam September 2003 In the American wire gauge, as the number of gauge increases, the diameter of wire ____ A. increases B. decreases C. does not change D. become twice 20. REE Board Exam September 2003 In cgs system, what is the unit of emf where I is in abampere and P is in erg per second? A. millivolt C. abvolt B. kilovolt D. volt 21. REE Board Exam September 2002 One (1) kW is equal to ____ hp. A. 0.746 C. 550 B. 1.34 D. 1.5 22. REE Board Exam October 1998 Two copper conductors have equal length. The cross-sectional area of one conductor is three times that of the other. If the resistance of the conductor having smaller cross-sectional area is 20 Ω, what is the resistance of the other? A. 20/3 Ω C. 180 Ω B. 60 Ω D. 20/9 Ω 23. REE Board Exam October 2000 A copper bar has a length of 20 ft., width of 4 inches and thickness of 0.5 inch. If the resistivity of copper is 10.37 Ω-CM/ft, what is the resistance of the bar? A. 81.4 μΩ C. 814 μΩ B. 8.14 μΩ D. 0.814 μΩ 24. REE Board Exam April 2001

17. REE Board Exam October 1999

The resistance of the field winding of a DC machine is 0.25 Ω at 25°C. When operating at full-load, the temperature of the winding is 75°C. The temperature coefficient of resistance of copper is 0.00427 per °C at 0°C. Find the resistance of the field winding at full-load. A. 0.298 Ω C. 0.512 Ω B. 0.315 Ω D. 0.271 Ω

B. watt second

D. joule

32. ECE Board Exam November 1995 What composes all matter whether a liquid, solid or gas? A. electrons C. protons B. atoms D. neutrons

25. REE Board Exam October 2000 A coil of copper has resistance of 5.46 Ω at 75°C. What will be its resistance at 25°C? A. 4.58 Ω C. 5.02 Ω B. 4.84 Ω D. 4.35 Ω

33. ECE Board Exam November 2001 What is a physical combination of compounds or elements NOT chemically combined that can be separated by physical means? A. substance C. mixture B. atom D. molecule

26. REE Board Exam April 2001 A certain generator generates 1,500,000 joules per minute. What is the output in kW? A. 50 C. 25 B. 500 D. 125

34. ECE Board Exam April 1998 Determine the equivalent work of 166 wattsecond. A. 10 joules C. 16.6 joules B. 100 joules D. 166 joules

27. ECE BOARD NOV 2001 _____ is anything that has weight had occupies space. It may be solid, liquid or gas. A. Amalgam C. Matter B. Alloy D. Compound

35. ECE Board Exam November 2001 One of the following is the best conductor of electricity. A. Air C. Carbon B. Copper D. Silicon

28. ECE Board Exam April 2000 It is defined as anything that occupies space and has weight. A. atom C. molecule B. compound D. matter

36. ECE Board Exam November 1999 What is the basic unit for measuring current flow? A. coulomb C. volt B. ampere D. atomic weight

29. ECE Board Exam November 1999 The lightest kind of atom or element A. hydrogen C. titanium B. helium D. oxygen

37. ECE Board Exam November 1995 ______ has a unit of electron volt A. Energy C. Current B. Potential difference D. Charge

30. ECE Board Exam November 1998 In order to have a good conductor material, such material shall have _____ valence electrons. A. one C. more than ten B. five D. twenty one

38. ECE Board Exam November 2001 The motion of charged particles especially colloidal particles through a relative stationary liquid under the influence of an applied electric provided. A. hysteresis C. electrophoresis B. electrolysis D. electro analysis

31. ECE Board Exam November 1997 Electric power refers to _____ A. volt ampere C. volt coulomb

39. ECE Board Exam April 2001

What is a symbol that represents a quantity or a single object? A. unit C. item B. number D. base 40. ECE Board Exam April 2000 Determine which of the following has the least number of electrons found at the outer shell. A. semi-insulator C. semiconductor B. insulator D. conductor 41. ECE Board Exam April 2001 The term describes a material whose resistance remains relatively constant with changes in temperature A. positive temperature coefficient B. negative temperature coefficient C. neutral temperature coefficient D. zero temperature coefficient 42. ECE Board Exam November 1998 Resulting effect when electron is made to move A. dynamic electricity C. lines of force B. static electricity D. magnetic lines

A chemical combination of elements can be separated by chemical means but not by physical means. It is created by chemically combining two or more elements. A. molecules C. matter B. compound D. mixture 47. ECE Board Exam April 2000 A substance which cannot be reduced to a simpler substance by chemical means A. atom C. matter B. molecule D. element 48. ECE Board Exam November 2001 Calculate the equivalent power in watt of 100 joules per second. A. 1.66 watts C. 16.66 watts B. 100 watts D. 1,000 watts 49. ECE Board Exam April 2001 It is a neutral particle that has no electrical charge. A. atom C. electron B. proton D. neutron 50. ECE Board Exam November 1999 Which material has more free electrons? A. mica C. conductor B. insulator D. dielectric

43. ECE Board Exam November 1997 One of the following characteristics of a resistive material which do not change its resistive value with respect to time is its _____ A. fidelity C. stability B. sensitivity D. selectivity

51. ECE Board Exam November 2001 The new and preferred term for conductance or mho A. Siemens C. Seaman B. She-man D. ROM

44. ECE Board Exam November 2001 What do you call the element that conducts electricity very readily? A. semi-conductors C. insulators B. conductors D. dielectric

52. ECE Board Exam April 2001 Represents the current flow produced by one volt working across one ohm of resistance. A. resistance B. ampere C. voltage D. electromotive force

45. ECE Board Exam April 2001 Which of the following material is referred to as a medium whereby electrons can move easily from atom to atom? A. insulator C. mica B. dielectric D. conductor

53. ECE Board Exam November 1995 When an atom gains an additional _____, it results to a negative ion. A. atom C. proton B. neutron D. electron

46. ECE Board Exam November 2001

54. ECE Board Exam November 1999

The definite discrete amount of energy required to move an electron from a lower shell to higher shell. A. quantum B. positive energy C. negative energy D. quanta 55. ECE Board Exam November 1999 What will happen to an atom if an electron is either taken out or taken into the same atom? A. becomes a negative ion B. becomes an ion C. becomes a positive ion D. nothing will happen 56. ECE Board Exam April 1999 The energy in an electron that is called the energy of motion A. electromotive force B. kinematics C. kinetic energy D. potential energy 57. ECE Board Exam November 1996 Electric charge of neutron is the same as ______. A. atom C. current B. electron D. proton 58. ECE Board Exam April 1998 Ion is _____. A. free electron B. nucleus without protons C. proton D. an atom with unbalanced charges 59. ECE Board Exam November 1997 An insulating element or material has capability of _____. A. storing voltage B. preventing short circuit between two conducting wires C. conducting large current D. storing high current 60. ECE Board Exam April 1998 What is the value of a resistor with colors from left: Orange, Blue, Gold and Silver? A. 34 ohms + /-10%

B. 36 ohms +/-10% C. 3.4 ohms +/-10% D. 3.6 0hms +/-10% 61. ECE Board Exam April 2001 A three-terminal resistor with one or more sliding contacts which functions as an adjustable voltage divider A. Rheostat C. Potentiometer B. Bleeder resistor D. Voltage divider 62. ECE Board Exam November A resistor which is used to amount of current A. potentiometer C. B. bleeder resistor D.

2000 draw a fixed fixed resistor rheostat

63. ECE Board Exam November 2001 Find the value of a resistor with the following color codes: Orange, Yellow, Red, Red A. 34 k ohms +/-5% B. 3.4 ohms +/-2% C. 3.4 k ohms +/-10% D. 34 k ohms +/-20% 64. ECE Board Exam November 1996 Electric energy refers to ______. A. Joules divided by time C. Watt B. Volt-ampere D. Volt-coulomb 65. ECE Board Exam April 2001 What is the resistance of an open fuse circuit? A. at least 1000 ohms B. infinity C. zero D. 100 ohms at standard temperature 66. ECE Board Exam April 1998 When should a fuse be replaced with a higher rated unit? A. when the fuse of the original value is small in size B. when the original is not available C. never D. if it blows 67. ECE Board Exam November 2000 The ability to do work

A. energy B. kinetic

C. potential D. voltage

D. Gray, gray, black

68. ECE Board Exam November 2001 Which type of variable resistor should you use for controlling large amount of current? A. Potentiometer C. Variac B. Adjustable wirewound D. Rheostat

75. ECE Board Exam November 1998 If the bands on a resistor are yellow, violet, red and gold, what is the resistance value? A. 470 ohms 5% B. 470 ohms 10% C. 47000 ohms 5% D. 4700 ohms 5%

69. ECE Board Exam April 2000 What does the fourth loop of an electronic resistor color code represent? A. Multiplier B. Temperature C. First digit of the equivalent value D. Tolerance

76. ECE Board Exam November 1997 Rust in electrical (wire) connections will result to _____ A. Conductance C. Voltage B. Resistance D. Inductance

70. ECE Board Exam November 2000 Ten micro-microfarads is equivalent to _____ A. 100 picofarads B. 100 nanofarad C. 1000 milli microfarad D. 10.0 picofarads 71. ECE Board Exam November 1995 How much is the resistance of a germanium slag 10 cm long and cross sectional area of 1 square cm? A. 55 k ohms C. 550 k ohms B. 5.5 k ohms D. 550 ohms

77. ECE Board Exam November 1996 The area of a conductor whose diameter is 0.001 inch is equal to A. One micron C. One circular mil B. One angstrom D. One steradian 78. ECE Board Exam November 1995 _____ is the term used to express the amount of electrical energy in an electrostatic field. A. Joule C. Volt B. Coulomb D. Watt

72. ECE Board Exam November 2001 A variable resistor normally used as a voltage divider A. Carbon film resistor B. Potentiometer C. Adjustable resistor D. Metal film resistor

79. ECE Board Exam November 1995 Which of the following statement is correct? A. Potentiometer has two terminals B. Transistor has two terminals C. Typical power rating of a carboncomposition resistor ranged from 0.125 W to 2 W D. Open resistor has small resistance

73. ECE Board Exam April 2001 Determine the equivalent horse power of 2.611 kilowatts. A. 3.50 hp C. 2.25 hp B. 2.50 hp D. 1.50 hp

80. ECE Board Exam November 1996 _____ is one factor that does not affect resistance. A. Resistivity C. Length B. Cross sectional area D. Mass

74. ECE Board Exam November 2000 Find the lowest resistance value of the following resistors. A. White, black, black B. Violet, gray, yellow, silver C. Red, black, gold

81. ECE Board Exam November 1998 What is the value of a resistor having the following colored bands: Yellow-Gray-RedSilver? A. 4800 ohms ±10%

B. 480 ohms ±10% C. 3800 ohms ±1% D. 4.8 ohms ±1% 82. ECE Board Exam November 1997 Find the value of resistor with the following color codes; Brown, White, Orange, Red A. 190 ohms 10% B. 19 k ohms 2% C. 1.9 k ohms 10% D. 19 k ohms 20% 83. ECE Board Exam November 1998 Resistor with colored bands in the body A. Adjustable resistor B. Wire-wound resistor C. Variable resistor D. Carbon composition resistor 84. ECE Board Exam November 1998 If the bands on a resistor are red, red, orange and silver, what is the resistance value? A. 220 ohms 5% B. 223 0hms 10% C. 22,000 ohms 10% D. 2200 ohms 20% 85. ECE Board Exam November 1997 What does the second strip of an electronic resistor color code represent? A. Tolerance B. Second digit of the value C. Temperature D. Multiplier 86. ECE Board Exam November 2000 The energy in an electron that is called the energy of position A. Kinetic energy B. Kinematics C. Electromotive force D. Potential energy

What happens to the resistance of a conductor wire when its temperature is lowered? A. Decreased C. Zero B. Steady D. Increased 89. ECE Board Exam April 1998 Which of the following does not refer to electric energy? A. Joule C. Volt coulomb B. Watt second D. Volt ampere 90. ECE Board Exam March 1996 Which of the following statement is incorrect? A. open transistor has three (3) terminals B. transistors have three (3) terminals C. typical power rating of carboncomposition resistor ranged 0.001 W to 0.1 W D. potentiometer has three (3) terminals 91. ECE Board Exam November 1997 Term used in electronic measuring device when a metal increases resistance due to heat produced by current flowing through them. A. positive resistance coefficient B. positive temperature coefficient C. negative temperature coefficient D. negative resistance coefficient 92. A 1 km cable consists of 12 identical strands of aluminum each 3 mm in diameter. What is the resistance of the cable? A. 0.34 ohm C. 0.44 ohm B. 0.54 ohm D. 0.24 ohm 93. A piece of wire has a resistance of 0.5 ohm. The length is doubled and the area is increased four times. What is its resistance? A. 0.75 ohm C. 0.25 ohm B. 0.50 ohm D. 1 ohm

87. ECE Board Exam April 1999 If an electronic resistor does not have the fourth color strip it means it has a tolerance of _____. A. 5% C. 10% B. 20% D. 1%

94. Copper wire of certain length and resistance is drawn out to four times its length without change in volume. What is the resistance of the bar? A. unchanged C. 16R B. R/16 D. 4R

88. ECE Board Exam April 1998

95. Current is simply _____.

A. Flow of electrons B. Flow of protons

C. Radiation D. Emission

96. The resistance of a coil of wire is 1 kΩ at 20°C. If the coil is immersed into oil, the resistance falls to 880 Ω. If the wire has a temperature coefficient of 0.006 at 20°C, how much is the temperature of the liquid? A. 0°C C. 17.6°C B. -20°C D. none of these 97. The copper field coils of a motor was measured at 21°C and found to have a resistance of 68 Ω. After the motor has run for a given time, the resistance is found to be 96 Ω. What is the hot temperature of the winding? A. 106.36°C C. 103.66°C B. 166.30°C D. none of these 98. A wire has a resistance of 30 Ω at 20°C. What will its resistance be at 60°C? Assume the temperature coefficient of resistance to be 0.000385 at 20°C. A. 34.26 Ω C. 32.46 Ω B. 36.42 Ω D. none of these 99. Determine the length of a copper wire (ρ = 10.37 Ω-CM/ft) where diameter is 0.30 inch and resistance of 0.5 Ω at 20°C. A. 4,339 ft C. 6,125 ft B. 5.225 ft D. none of these 100. An electric water heater has a rating of 1 kW, 230 V. The coil used as the heating element is 10 m long and has a resistivity of 1.724 x 10-6 ohm-cm. Determine the required diameter of the wire in mils. A. 2.43 mils C. 3.21 mils B. 2.52 mils D. 1.35 mils 101. A certain wire 20 ft long and 100 circular mil area has a resistance of 1.6 . What is its resistivity? A. 10.3 ohm-CM/ft B. 2.2 ohm-CM/ft C. 8 ohm-CM/ft D. 15.2 ohm-CM/ft

102. circular mils does a round inch diameter have? A. 196,000 B. 62,500

How many copper rod of 0.25 C. 1,963,500 D. 49,000

103. A substance whose molecules consist of the same kind of atoms is called ____. A. mixture B. element C. compound D. none of the above 104. the atom is about ____. A. 10-10 m B. 10-8 m

The diameter of C. 10-2 m D. 10-15 m

105. The number of compounds available in nature is ____. A. 105 C. 1000 B. 300 D. unlimited 106. The mass of a proton is ____ the mass of an electron. A. equal to B. less than C. about 1837 times D. 200 times 107. The maximum number of electrons that can be accommodated in the last orbit is ____. A. 4 C. 18 B. 8 D. 2 108. The electrons in the last orbit of an atom are called ____ electrons. A. free C. valence B. bound D. thermionic 109. If the number of valence electrons of an atom is less than 4, the substance is usually ____. A. a conductor B. an insulator C. a semiconductor D. none of the above

110. If the number of valence electrons of an atom is more than 4, the substance is usually ____. A. a semiconductor B. a conductor C. an insulator D. none of the above 111. If the number of valence electrons of an atom is exactly 4, the substance is usually ____. A. a semiconductor B. an insulator C. a conductor D. a semiconductor 112. The number of valence electrons of an atom is less than 4. The substance will be probably ____. A. a metal B. a non-metal C. an insulator D. a semiconductor 113. One coulomb of charge is equal to the charge on ____ electrons. A. 628 x 1016 C. 62.8 x 1016 16 B. 6.28 x 10 D. 0.628 x 1016 114. has about ____ temperature. A. 200 B. 20 x 1010

free

115. a wire is the flow of ____. A. free electrons B. bound electrons C. valence electrons D. atoms

One cc of copper electrons at room C. 8.5 x 1022 D. 3 x 105 Electric current in

116. EMF in a circuit is ____. A. cause current to flow B. maintains potential difference C. increases the circuit resistance D. none of these

117. of _____. A. power B. energy

EMF has the unit C. charge D. none of these

118. Potential difference has the unit of ____ . A. charge B. power C. energy D. none of the above 119. The resistance of a material is ____ its area of cross-section. A. directly proportional to B. inversely proportional to C. independent of D. none of the above 120. If the length and area of cross-section of a wire are doubled up, then its resistance ____. A. becomes four times B. remains unchanged C. becomes sixteen times D. none of the above 121. A length of wire has a resistance of 6 ohms. The resistance of a wire of the same material three times as long and twice the cross-sectional area will be ____. A. 36 ohms C. 9 ohms B. 12 ohms D. 1 ohm 122. specific resistance is ____. A. mho B. ohm-m

The

SI

unit

of

C. ohm-m2 D. ohm-cm

123. The specific resistance of a conductor ____ with rise in temperature. A. increases B. decreases C. remains unchanged D. none of the above 124. conductivity is ____. A. ohm-m B. ohm/m

The

SI

unit

C. mho-m D. mho/m

of

125. conductance is ____. A. mho B. ohm

The

SI

unit

of

C. ohm-m D. ohm-cm

126. The resistance of a material 2 m long and 2 m2 in crosssectional area is 1.6 x 10-8 Ω. Its specific resistance will be ____. A. 3.2 x 10-8 ohm-m B. 6.4 x 10-8 ohm-m C. 1.6 x 10-8 ohm-m D. 0.16 x 10-8 ohm-m

D. none of the above 132. Eureka has ____ temperature coefficient of resistance. A. positive B. negative C. almost zero D. none of the above 133. Fig. 1.1 the temperature/resistance graph conductor. The value of α0 is ____.

shows of a

127. Conductors have ____ temperature coefficient of resistance. A. positive B. negative C. zero D. none of the above 128. Semiconductors have ____ temperature coefficient of resistance. A. negative B. positive C. zero D. none of the above 129. The value of α (i.e. temperature coefficient of resistance) depends upon A. length of the material B. cross-sectional area of the material C. volume of the material D. nature of the material and temperature 130. The temperature coefficient of resistance of a conductor ____ with rise in temperature. A. increases B. decreases C. remains unchanged D. none of the above 131. Insulators have ____ temperature coefficient of resistance. A. zero B. positive C. negative

A. 0.005/°C B. 0.004/°C

C. 0.1/°C D. 0.4/°C

134. Referring to Fig. 1.1, the value of the α50 will be ____.

A. 0.005/°C B. 0.004/°C

C. 0.1/°C D. 0.4/°C

135. Referring to Fig. 1.2, the value of α0 is ____. A. 1/30 per °C B. 1/40 per °C C. 1/1200 per °C D. none of the above 136. Referring to Fig. 1.2, the value of R40 will be ____.

141. Two wires A and B have the same cross-section and are made of the same material, RA = 600 Ω and RB = 100 Ω. The number of times A is longer than B is A. 6 C. 4 B. 2 D. 5



137. Referring to Fig. 1.2, the value of α40 will be ____.

142. A resistance of 100 Ω at 90°C. resistance is 101 Ω. The coefficient of wire at 90°C is A. 0.01 C. B. 0.1 D.

coil has a At 100°C, its temperature 0.0001 0.001

143. Which of the following material has nearly zero temperature-coefficient of resistance? A. carbon C. copper B. porcelain D. manganin

A. 1/30 per °C B. 1/70 per °C

C. 1/50 per °C D. 1/1200 per

°C

144. Which of the following material has a negative temperature coefficient of resistance? A. brass C. aluminum B. copper D. carbon

138. The value of α0 of a conductor is 1/236 per °C. The value of α 18 will be ____. A. 1/218 per °C B. 1/272 per °C C. 1/254 per °C D. none of the above

145.

139. The value of α50 of a conductor is 1/230 per °C. The value of α0 will be ____. A. 1/180 per °C B. 1/280 per °C C. 1/250 per °C D. none of the above

146. Carbon composition resistors are most because they A. cost the least B. are smaller C. can withstand overload D. do not produce electric noise

140. A good electric conductor is one that A. has low conductance B. is always made of copper wire C. produces a minimum voltage drop D. has few free electrons

A cylindrical wire

1 m in length, has a resistance of 100 . What would be the resistance of a wire made from the same material both the length and the cross-sectional area are doubled? A. 200 C. 100 B. 400 D. 50

popular

147. A unique feature of a wire-wound resistor is its A. lower power rating C. high stability B. low cost D. small size 148. A coil has a resistance of 100 ohms at 90 °C. At 100°C, its

resistance is 101 ohms. What is the temperature coefficient of the wire at 90°C? A. 0.01 C. 0.0001 B. 0.1 D. 0.001 149. for charge (Q)? A. Farad B. Joule

What is the unit C. Siemens D. Coulomb

150. The charge delivered by a constant voltage source is shown. Determine the current supplied by the source at (a) t = 1 s (b) t = 3 s.

A.

5 ma, -3.33 ma

C. –3.33 ma, 5

ma B. 5 ma, 3.33 ma

D. 3.33

ma,

5

ma B. OHM’S LAW AND ELECTRIC CIRCUITS 151. REE Board Exam October 1998 The resistance of 120 meters of wire is 12 ohms. What is its conductance? A. 0.0521 siemens C. 6 siemens B. 0.0833 siemens D. 12 siemens 152. EE April 1981, October 1984 Two (2) 115-V incandescent lamps A and B are connected in series across a 230-V source. If lamp A is rated 75 watts and lamp B is rated 50 watts, determine the current drawn by the series connection. A. 0.52 A C. 0.48 A B. 0.64 A D. 0.57 A 153. REE Board Exam March 1998 Three resistors of 10, 15 and 20 ohms each are connected in parallel. What is the equivalent resistance? A. 45 ohms C. 0.22 ohm B. 17.2 ohms D. 4.62 ohms 154. REE Board Exam March 1998 Three resistors of 10, 15 and 20 ohms each are connected in parallel. What is the total conductance?

A. 0.217 siemens B. 3.41 siemens siemens

C. 4.52 siemens D. 0.562

155. REE Board Exam October 1997 A 5-ohm resistance is connected in parallel with a 10-ohm resistance. Another set, a 6ohm and an 8-ohm resistances are also connected in parallel. The two sets are connected in series. What is the equivalent resistance? A. 6.76 ohm C. 14.4 ohms B. 9.25 ohm D. 21.2 ohms 156. REE Board Exam March 1998 Two resistances of 10 and 15 ohms each respectively are connected in parallel. The two are then connected in series with a 5ohm resistance. What is the equivalent resistance? A. 11 ohms C. 10 ohms B. 12 ohms D. 9 ohms 157. REE Board Exam October 1997 A 10-ohm and a 20-ohm resistance are connected in parallel. Another resistance of 5-ohm is connected in series with the two. If the supply voltage is 48 volts, what is the current through the 10-ohm resistor? A. 3.21 A C. 4.02 A B. 2.74 A D. 5.72 A 158. REE Board Exam March 1998 Two resistances of 10 and 15 ohms, each respectively are connected in parallel. The two are then connected in series with a 5ohm resistance. It is then connected across a 12-V battery, what are the current and power? A. 1.2 A, 17.28 W C. 1.09 A, 13.1 W B. 0.96 A, 11.52 W D. 1.5 A, 20.25 W 159. REE Board Exam September 2001 Three resistors 10-Ω, 15-Ω and 20-Ω are connected in series across a 48-V source. What is the voltage across the 15-Ω resistor? A. 20 V C. 24 V B. 16 V D. 12 V

160. REE Board Exam September 2001 Three resistors 10-Ω, 15-Ω and 20-Ω are connected in parallel. What is the total resistance? A. 3.56 Ω C. 0.217 Ω B. 4.62 Ω D. 45 Ω

161. REE Board Exam September 2000 Two 10-Ω resistances are connected in parallel. The two are then connected in series with a 5-Ω resistance. It is then connected across a 24-volt battery; find the voltage across the 5-Ω resistor. A. 12 volts C. 9 volts B. 24 volts D. 15 volts 162. REE Board Exam April 1997 A circuit consists of three resistors rated 3-Ω, 4-Ω and 5-Ω connected in parallel. If the circuit is connected to a battery which has an internal resistance of 0.2-Ω, what would be the current through the 4-Ω resistor? A. 2.04 A C. 2.4 A B. 4.8 A D. 3.0 A 163. REE Board Exam September 2000 How many abvolts in 1 volt? A. 108 abvolts C. 1 abvolt B. 10-8 abvolts D. 10 abvolt 164. REE Board Exam September 2003 A total current of 60 A is divided among 3 parallel branches having resistances of 10 Ω, 6 Ω and 12 Ω, respectively. What is the current that flows through the branch with 10 Ω resistance? A. 17.1 A C. 14.3 A B. 28.6 A D. 42.9 A 165. REE Board Exam October 2000 Two 10-ohm parallel resistors are connected in series with a 5-ohm resistor. The combination is then connected across a 24 volts battery. Find the voltage drop across the 5-ohm resistor. A. 6 V C. 12 V B. 18 V D. 20 V 166.

The theory of Ohm’s law is applied in a _____ circuit. A. linear C. trivalent B. exponential D. unilateral 167. ECE Board Exam April 2000 Refers to the most important components in controlling flow of electrons A. voltage, electromotive force and current B. reactance, current and resistance C. conductance, resistance and reactance D. voltage, resistance and current 168. ECE Board Exam November 1999 Which of the following is not a valid expression of ohm’s law? A. E = IR C. R = E/I B. R = PI D. I = E/R 169. ECE Board Exam November 2000 A simple electronic equipment which takes a 2 amperes current from a power source has a total load resistance of 100 ohms. How much power does it use? A. 200 watts C. 400 watts B. 100 watts D. 50 watts 170. ECE Board Exam November 1996 What do you expect when you use the two 20 kohms, 1 watt resistor in parallel instead of one 10 kohms, 1 watt? A. Provide lighter current B. Provide wider tolerance C. Provide more power D. Provide less power 171. ECE Board Exam November 1999 The total resistance of a two similar wire conductors connected in parallel is ______ A. same resistance of one wire B. double the resistance of one wire C. one half the resistance of one wire D. resistance of one wire multiplied by 4 172. ECE Board Exam March 1996 When you increase the resistance in a circuit, the flow of electrons will ______. A. be constant C. be stopped B. flow faster D. be decreased

ECE Board Exam November 1998 173.

ECE Board Exam April 2001

Which of the following allows more current if applied to the same voltage? A. 0.002 siemen C. 0.004 siemen B. 25 ohms D. 2.5 ohms 174. ECE Board Exam April 1998 Ohm’s law refers to _____. A. power is directly proportional to both voltage squared and the resistance B. power is directly proportional to the resistance and inversely as the current squared C. current varies directly as the voltage and inversely as the resistance D. current is directly proportional to both voltage and resistance 175. ECE Board Exam November 2000 A circuit which a break exists in the complete conduction pathway A. Open circuit C. Close circuit B. Short circuit D. Circuit 176. ECE Board Exam November 1997 How much is the equivalent power in watts can a 3 horse power provide? A. 3000 watts C. 1492 watts B. 248.66 watts D. 2238 watts 177. ECE Board Exam March 1996 The current needed to operate a soldering iron which has a rating of 600 watts at 110 volts is A. 18,200 A C. 66,000 A B. 0.182 A D. 5.455 A

178. ECE Board Exam November 1997 Find the power across the resistor of 5 ohms delivered from a battery of an internal resistance of 3 ohms and a constant emf of 4 volts. A. 120 watts C. 60 watts B. 100 watts D. 1.25 watts 179.


A series circuit in which desired portions of the source voltage may be tapped off for use equipment. A. Voltage trap B. Voltage selector C. Voltage divider D. Dividing network 180. ECE Board Exam April 1998 An electronic device draws 300 watts from its 24 volt power source. Find effective resistance. A. 1.25 Ω C. 19.20 Ω B. 1.92 Ω D. 12.50 Ω 181. ECE Board Exam November 1997 How much power does an electronic equipment consume, assuming a 5.50 amperes current flowing and a 120 volts power source? A. 125.5 watts C. 660 watts B. 66 watts D. 60 watts 182. ECE Board Exam March 1996 What type of circuit whose parameters are constant which do not change with voltage or current? A. Tuned circuit C. Reactive circuit B. Linear circuit D. Lumped circuit 183. ECE Board Exam April 2000 If three circuits, each with a value of 560 ohms are connected in parallel, what is the total resistance of the combination? A. 1680 ohms C. 18567 ohms B. 560 ohms D. 187 0hms 184. ECE Board Exam November 1997 Other factors remaining constant, what would be the effect on the current flow in a given circuit if the applied potential were doubled? A. It would double B. It would increase 4 times C. It would remain the same D. It would be decrease by ½ 185.


Find used power of a circuit whose power source supplies 20 volts and a load resistance of 200 ohms. A. 1 watt C. 10 watts B. 4 kilowatts D. 2 watts

If 12 V are applied to a circuit that consumes 78 W, what is the current flow through the circuits? A. 6.5 A C. 0.15 A B. 936 A D. 9.36 A

186. ECE Board Exam April 1998 When resistors are connected in series, what happens? A. Nothing B. The tolerance is decreased C. The effective resistance is decreased D. The effective resistance is increased

193. ECE Board Exam April 1998 Find the current that flows through the filament of a 400 watt flat iron connected to a 220 volt power line. A. 50 mA C. 5 mA B. 500 mA D. 5 A

187. ECE Board Exam November 1999 A condition in which the heat in of around the circuit increases beyond or to a higher than normal level. A. Excessive heat condition B. Open condition C. Direct short D. Grounded 188. ECE Board Exam November 1999 A 33 kilo ohms resistor is connected in a series parallel combination made up of a 56 kilo ohm resistor and a 7.8 kilo ohm resistor. What is the total combined resistance of these three resistors? A. 39067 ohms C. 63769 ohms B. 49069 ohms D. 95800 ohms 189. ECE Board Exam April 2001 If 3,300 ohms resistor and a 22,000 ohms resistor are connected in series, what is the total resistance? A. 18,700 ohms C. 5,500 ohms B. 25,300 ohms D. 2,870 ohms 190. ECE Board Exam November 2000 A device that draws current A. Source C. Load B. No load D. Shunt 191. ECE Board Exam April 1998 With the same voltage applied which of the following allows more current? A. 25 ohms C. 2.5 ohms B. 250 ohms D. 0.25 ohms 192.


194. Four equal resistances are connected in parallel across a certain supply producing P power. How much power will be produced if the resistances are now connected in series across the same supply? A. 16P C. 4P B. P/16 D. P/4 195. A resistor R is connected across a 120 V supply. A voltmeter of 10,000 ohms resistance is connected between the center of the resistor and one side of the supply and reads 40 V. What is the value of the resistance R? A. 10,000  C. 30,000  B. 20,000 

D. 15,000 

196. A 240 V motor requiring 2,000 W is located 1 km from a power source. What diameter of copper wire is to be used if the power loss is to be kept 5%? A. 0.49 cm C. 0.39 cm B. 0.54 cm D. 0.35 cm 197. Three resistors of 10, 12 and “x” ohms, respectively are connected in parallel across a constant current source of 8 A. Determine “x” if this resistor draws 2.5 A. A. 10 Ω C. 13 Ω B. 12 Ω D. 11 Ω 198. An arc lamp takes 10 A at 50 volts. A resistance R is to be place in series so that the lamp my burn

correctly from a 110 V supply. Find the power wasted in this resistor. A. 800 watts C. 700 watts B. 600 watts D. 900 watts 199.

A 20  and 10 

resistors are connected in parallel and a 5  resistor is connected in series with the parallel combination. The circuit is connected across a 48 V source with an internal resistance of 0.2 . Calculate the current through the 5  resistor. A. 5.57 amperes B. 4.04 amperes

C. 3.58 amperes D. 7.63 amperes

200. A variable resistor R is connected in parallel with a fixed resistor of 1.25 ohms. The combination is then connected across a 12 V battery with internal resistance of 0.25 Ω. Solve for the maximum power that can delivered to R. A. 130.20 W C. 120.21 W B. 115.52 W D. 142.42 W 201. The resistance of an incandescent lamp is ohms and the rated voltage is 50 V. Find series resistance required to operate lamp from an 80 V supply. A. 8  C. 6  B. 4 

hot 10 the the

D. 10 

202. applicable to A. copper B. silver C. silicon carbide D. aluminum

Ohm’s law is not

203. of electrical energy is A. watt B. kilowatt C. kilowatt-hour D. megawatt

The practical unit

204. A 100 watt lamp working for 20 hours will consume ____ units. A. 200 C. 2 B. 20 D. 5

205. The hot resistance of an incandescent lamp is about ____ its cold resistance. A. 10 times C. 100 times B. 2 times D. 50 times 206. A d.c. usually has ____ as the load. A. resistance B. inductance C. capacitance D. both inductance and capacitance

circuit

207. The purpose load in an electric circuit is to ____. A. increase the circuit current B. utilize electrical energy C. decrease the circuit current D. none of the above

of

208. Electrical appliances are not connected in series because ____ A. series circuit is complicated B. appliances have different current rating C. power loss is more D. none of the above 209. Electrical appliances are connected in parallel because it ____ A. is a simple circuit B. draws less current C. results in reduce in power loss D. makes the operation of appliances independent of each other 210. Inductance and capacitance are not relevant in a d.c. circuit because ____ A. frequency of d.c. is zero B. it is a simple circuit C. they do not exist in a d.c. circuit D. none of the above 211. The hot resistance of a 100 watt, 250 V incandescent lamp would be A. 2.5 ohms

B. 625 ohms C. 25 ohms D. none of the above 212. The voltage drop across 14.5 ohm resistor in Fig. 2.1 is ____.

A. 29 V B. 14 V

C. 30.5 V D. 18 V

213. The circuit shown in Fig. 2.1 is called a series circuit because ____

A. it contains a few resistances B. it carries the same throughout the circuit C. it is a simple circuit D. none of the above

current

214. Referring to Fig. 2.2, the total circuit resistance will be ____

A. the lamp A will be brighter than lamp B B. the lamp B will be brighter than lamp A C. the two lamps will be equally bright D. none of the above 216. When a number of resistances are connected in parallel, the total resistance is ____ A. less than the smaller resistance B. greater than the smaller resistance C. between the smaller and greatest resistance D. none of the above 217. Two resistances of 6 ohms and 3 ohms are connected in parallel. The total resistance is ____ A. 9 ohms C. 0.5 ohm B. 18 ohms D. 2 ohms 218. The value of R that will give a total resistance of 1.5 ohms in Fig. 2.3 is ____

A. 4 ohms B. 6 ohms A. 1000 ohms B. 400 ohms 215.


C. 3 ohms D. 9 ohms

219. The current in 2.5 ohm resistor in Fig. 2.4 will be ____

In Fig. 2.2 ____

A.

3A

C. 2.5 A

B. 4.5 A

D. 2 A

220. The current in 4.5 ohms resistor in Fig. 1.4 will be ____.

A. 10 A B. 5 A A. 3.5 A B. 3 A

C. 2 A D. 2.5 A

221. If 18 resistances, each of value 36 ohms, are connected in parallel, then the total resistance is ____ A. 2 ohms B. 54 ohms C. 36 ohms D. none of the above 222. Two incandescent lamps of 100 W, 200 V are in parallel across 200 V supply. The total resistance will be ____. A. 800 ohms C. 400 ohms B. 200 ohms D. 600 ohms

C. 12 A D. 6 A

225. The resistance across terminals AC in Fig. 2.5 is ____



226. The resistance across terminals AB of the circuit shown in Fig. 2.6 is ____

223. The resistance across the terminals AB of the circuit shown in Fig. 2.5 is ____ A. 4 ohms B. 18 ohms




227. If a battery of 24 V is applied across terminals AB of the circuit shown in Fig. 2.6, then current in 2 ohm resistor will be ____

224. If a d.c. supply of 180 V is connected across terminals AB in Fig. 2.5, then current in 6 ohm resistor will be ____. A. 3 A B. 6 A

C. 2.5 A D. 1.5 A

228. If a battery of 24 V is applied across terminals AB in Fig. 2.6,

then power loss in 5 ohms resistor will be ____

A. 180 W B. 45 W

C. 90 W D. 24 W

229. The total conductance of the circuit shown in Fig. 2.7 is ____

A. 13 mhos B. 1.6 mhos

C. 6 mhos D. 2.5 mhos

230. If 10 ohms resistance is removed in Fig. 2.7, then total conductance of the circuit will be ____

A. 3 mhos B. 6 mhos

C. 2 mhos D. 1.5 mhos

231. The voltage across the parallel circuit shown in Fig. 2.8 is ____

A. 15 V B. 10 V

C. 30 V D. 12. 5 V

232. The current in 10 ohms resistor in Fig. 2.8 is ____

A. 3 A B. 2.5 A

C. 1.5 A D. 3.5 A

233. The total resistance between terminals 1 and 2 of the circuit shown in Fig. 2.9 is ____

A. 12 ohms B. 2.67 ohms


234. If a battery of 12 V is applied across terminals 1 and 2 of Fig. 1.9, then current through 4 ohms resistor will be ____

A. 1.5 A B. 3 A

C. 2 A D. 2.5 A

235. The resistance between terminals 1 and 2 of Fig. 1.10 is ____



236. The resistance between terminals 1 and 2 in Fig. 1.11 is ____

A. 2 ohms B. 1.5 ohms

C. 1 ohm D. 4 ohms

237. If a battery of 6 V is applied across terminals 1 and 2 in Fig. 1.11, then current in the horizontal 2 ohm resistor will be ____

A. 1 A B. 2 A

C. 3 A D. 0.5 A

238. The resistance across terminals 1 and 2 in Fig. 1.12 is ____

A. B. C. D.

9 ohms 18 ohms 10 ohms none of the above

241. Referring to Fig. 1.13, the resistance across terminals AF is ____

A. B. C. D.

20.5 ohms 18 ohms 11 ohms none of the above

242. Referring to Fig. 1.13, the current in 18 ohms resistor will be ___



239. Two equal resistances are connected in series across a certain supply. If the resistances are now connected in parallel across the same supply, the power produced will be ____ that of series connection. A. two times C. one-half B. four times D. one-fourth 240. Referring to Fig. 1.13, the resistance across terminals BE is ____

A. B. C. D.

2A 1.5 A 1A none of the above

243. Referring to Fig. 1.13, the power loss in 11 ohms will be ____

A. B. C. D.

A. B. C. D.

11 W 24 W 16 W none of the above

244. If in Fig. 1.14, switches S1 and S2 are closed, then total circuit resistance is ____



245. If switch S1 is open and switch S2 is closed in Fig. 1.14, then circuit resistance will be ____



246. If in Fig. 1.14, both switches S1 and S2 are closed, then ____

L1 will be brighter than L2 or L3 L1 will be dimmer than L2 or L3 L1 will be as bright as L2 or L3 none of the above

247. If in Fig. 1.14 switches S1 and S2 are open, then lamp L1 will give output ____

A. B. C. D.

less than 40 W more than 40 W equal to 40 W none of the above

248. If in Fig. 1.14 switches S1 and S2 are closed and the supply voltage is increased to 400 V, then ____

A. B. C. D.

lamp L1 will burn out lamp L2 will burn out both lamps L2 and L3 will burn out all the lamps will be safe

249. If in Fig. 1.1, resistor R2 becomes open-circuited, the reading of the voltmeter will become

Figure 1.3 Figure 1.1 A. zero B. 150 V

C. 50 V D. 200 V

250. Whatever the battery voltage in Fig. 1.2, it is certain that smallest current will flow in the resistance of ____ ohm.

A. 12 B. 24

C. 0 D. -12

254. In the series circuit of Fig 1.4, the value of V0 is ____ volt.

Figure 1.4 A. 12 B. -12 Figure 1.2 A. 300 B. 500

C. 200 D. 100

251. Which of the following statement is TRUE both for a series and parallel d.c circuit? A. powers are additive B. voltages are additive C. current additive D. elements have individual currents 252. A 100-W, 110-V and a 50-W lamp are connected in series across a 220-V dc source. If the resistances of the two lamps are assumed to remain constant, the voltage across the 100-W lamp is ____ volt. A. 110 C. 146.7 B. 73.3 D. 220 253. In the parallel circuit of Fig.1.3, the value of V0 is ____ volt.

C. 0 D. 6

255. In Fig 1.5, there is a drop of 20 V on each resistor. The potential of point A would be ____ volt.

Figure 1.5 A. +80 B. -40

C. +40 D. -80

256. From the voltmeter reading of Fig. 1.6, is it obvious that

Figure 1.6 A. the 3  resistor is short circuited B. the 6  resistor is short circuited C. nothing is wrong with the circuit

D. the 3  resistor is open-circuited 257. With reference to Fig 1.7, which of the following statement is true?

A. B. C. D.

Figure 1.7 E and R1 form a series circuit R1 is in series with R3 R1 is in series with R2 there is no series circuit

258. Which of the following statements is correct concerning the Fig. 1.8?

C. Wire-Wound Type D. Non-linear Resistor 261. A 100 W, 110 V and 50 W, 110 V lamps are connected in series across a 220 V DC source. If the resistances of the two lamps are assumed to remain constant, the voltage across the 100 W lamp is _____ volt? A. 110 V C. 146.7 V B. 73.3 V D. 220 V 262. A potential divider of resistance of 50 ohms is connected across a 100 V DC source. A load resistance of 10 ohms is connected across a tap in the potential divider and the negative terminal of the source. If a current of 4 A flows towards the load, what is the current supplied by the source? A. 5.32 A C. 5.21 A B. 5.05 A D. 5.48 A 263. Two resistors A and B made of different materials have temperature coefficients of resistance at

A. B. C. D.

Figure 1.8 R2 and R3 form a series of path E is in series with R1 R1 is in parallel in R3 R1, R2 and R3 form a series of circuit

259. What is the equivalent resistance in ohms between points A and B of Fig. 1.9? All resistances are in ohms

20C of 0.004 and 0.006 respectively. When connected across a voltage source at 20C, they draw current equally. What percentage of the total current at 100C does resistor A carry? A. 47.14% C. 61.34% B. 52.86% D. 38.66% 264.

at 20C. A. 1/300 /°C B. 1/400 /°C Figure 1.9 A. 12 B. 14.4

C. 22 D. 2

260. What do you call a resistor that does not obey Ohm’s Law? A. Potentiometer B. Carbon-Film Resistor

A conductor has

a resistance of 7 ohms at 0C. At 20C, the resistance has become 7.5 ohms. Calculate the temperature coefficient of the conductor C. 1/500 /°C D. 1/600 /°C

265. Which of following is a non-linear element? A. diode B. heater coil C. transistor D. electric arc with unlike electrode C. ELECTRICAL AND HEAT ENERGY 266. EE Board Exam April 1992

the

An electric kettle was marked 500 W, 230 V found to take 15 minutes to bring 1 kilogram of water at 15°C to boiling point. Determine the heat efficiency of the kettle. A. 79.1% C. 72.4% B. 75.3% D. 74.8% 267. REE Board Exam October 1997 A process equipment contains 100 gallons water at 25°C. It is required to bring it boiling in 10 minutes. The heat loss estimated to be 5%. What is the kW rating the heater? A. 125 kW C. 50.5 kW B. 252 kW D. 207 kW

of to is of

268. EE October 1989 A total of 0.8 kg of water at 20°C is placed in a 1-kW electric kettle. How long a time in minute is needed to raise the temperature of the water to 100°C? A. 4.46 min C. 5.34 min B. 5.32 min D. 4,.56 min 269. REE October 1998 How many calories does an electric heater of 100 watts generate per second? A. 10 C. 23.88 B. 1000 D. 42.25 270. REE Board Exam October 1997 The electric energy required to raise the temperature of water in a pool is 1000 kWh. If the heat losses are 25%, the heating energy required will be ____. A. 1111 kWh C. 1750 kWh B. 1266 kWh D. 1333 kWh 271. EE Board Exam April 1992 An electric heater carries 12 A at 110 V, is submerged in 22.5 lbs of water for 30 minutes. What will be the final temperature of the water if its initial temperature is 35°F? A. 135.43°F B. 125.42°F

C. 133.56°F D. 128.33°F

272. EE Board Exam October 1990 In an electric heater the inlet temperature is 15°C. Water is flowing at the rate of 300 grams per minute. The voltmeter measuring voltage across the heating element reads 120 volts and an ammeter measuring current taken reads 10 amperes. When steady state

is finally reached, what is the final reading of the outlet thermometer? A. 57.6°C C. 72.6°C B. 68.4°C D. 42.6°C 273. EE Board Exam October 1991 Four cubic meters of water is to be heated by means of four 1.5 kW, 230-V immersion heating elements. Assuming the efficiency of the heater as 90%, determine the time required in boiling the water if the initial temperature is 20°C and if all four elements are connected in parallel. A. 71 hrs C. 69 hrs B. 63 hrs D. 66 hrs 274. EE Board Exam October 1991 Four cubic meters of water is to be heated by means of four 1.5 kW, 230-V immersion heating elements. Assuming the efficiency of the heater as 90%, determine the time required in boiling the water if the initial temperature is 20°C and if the elements are connected two in series in parallel with two in series. A. 275.6 hrs C. 252.2 hrs B. 295.3 hrs D. 264.4 hrs 275. REE Board Exam September 2001 How many joules per second are then in 10 watts? A. 10 C. 20 B. 5 D. 24.5 276. REE Board Exam September 2001 1013 ergs/sec is equal to how many kilowatts? A. 1,000 C. 100 B. 250 D. 10 277. REE Board Exam September 2000 What is 1 kW-hr in BTU? A. 4,186 C. 746 B. 3,413 D. 1,000 278. REE Board Exam October 1998 What is the work in ergs needed to raise a 10 g weight 100 m up? A. 4.9 x 105 C. 98 x 107 7 B. 9.8 x 10 D. 1.96 x 107 279.

REE Board Exam October 1999

The quantity of heat required to raise the temperature of water by 1°C. A. energy C. calorie B. specific heat D. BTU 280. REE Board Exam October 1999 When heat is transferred into any other form of energy or when other forms of energy are converted into heat, the total amount of energy is constant. This is known as A. First law of thermodynamics B. Boyle’s law C. Specific heat D. Isothermal expansion 281. REE Board Exam September 2002 What is 1012 ergs/sec in kW? A. 100 kW C. 10 kW B. 1,000 kW D. 10,000 kW 282. REE Board Exam October 2000 An electric heater is used to heat up 600 grams of water. It takes 14 minutes to raise the temperature of water by 40°C. If the supply voltage is 220 volts, what is the power rating of the heater neglecting heat losses? A. 180 W C. 200 W B. 120 W D. 60 W 283. REE Board Exam April 2001 A 100 liter of water is heated from 20°C to 40°C. How many kWHR of electricity is needed assuming no heat loss? A. 4.2 C. 5.6 B. 2.3 D. 3.7 284. Ten A. B.

REE Board Exam April 2002 (10) kW is equal to ____ gram-cal/sec. 156 C. 2,388 436 D. 425

285. ECE Board Exam November 1995 Two heaters A and B are in parallel across supply voltage V. Heater A produces 500 kcal in 20 minutes and B produces 1000 kcal in 10 minutes. The resistance of A is 10 ohms. What is the resistance of B, if the same heaters are connected in series voltage V? A. 4.5 ohms C. 4.5 ohms B. 2.5 ohms D. 0.14 ohm 286. In the SI system of units, the unit of force is

A. kg-wt B. Newton

C. Joule D. N-m

287. electric charge is A. ampere-hour B. watt-hour

The basic unit of

288. energy is A. Joule B. kWh

The

289. energy is A. Joule B. kWh

The

C. coulomb D. farad SI

unit

of

unit

of

C. kcal D. m-kg SI

C. kcal D. m-kg

290. Two heating elements, each of 230-V, 3.5 kW rating are first joined in parallel and then in series to heat same amount of water through the same range of temperature. The ratio of the time taken in the two cases would be A. 1:2 C. 1:4 B. 2:1 D. 4:1 291. If a 220 V heater is used on 110 V supply, heat produced by it will be ____ as much A. one-half C. one-fourth B. twice D. four times 292. For a given line voltage, four heating coils will produce maximum heat when connected A. all in parallel B. all in series C. with two parallel pairs in series D. one pair in parallel with the other two in series 293. The electric energy required to raise the temperature of a given amount of water is 1000 kWh. If heat losses are 25%, the total heating energy required is ____ kWh. A. 1500 C. 1333 B. 1250 D. 1000 294. energy equals nearly

One

kWh

of

A. 1000 W B. 860 kcal

C. 4186 J D. 735.5 W

295. A force of 10,000 N accelerates a body to velocity 0.1 km/s. The power developed is ____ kW. A. 1,000,000 C. 3600 B. 36,000 D. 1000 296. A 100 W light bulb burns on an average of 10 hours a day for one week. The weekly consumption of energy will be ____ unit/s. A. 7 C. 0.7 B. 70 D. 0.07 297. Two heaters, rated at 1000 W, 250 volts each, are connected in series across a 250 volt, 50 Hz A.C. mains. The total power drawn from the supply would be ____ watt. A. 1000 C. 250 B. 500 D. 2000 298. to ____. A. 4.19 cal/sec B. 778 BTU/sec

One watt is equal C. 107 ergs/sec D. 10-7 ergs/sec

299. The current in an electric lamp is 5 amperes. What quantity of electricity flows toward the filament in 6 minutes? A. 30 C C. 72 C B. 3600 C D. 1800 C 300. An electric heater is rated at 120 volts, 1000 watts and is used to boil water. Calculate the time in minutes to raise the temperature of 1 liter of water from 15°C to boiling. The heater has an over-all efficiency of 92%. A. 6.4 minutes C. 4.4 minutes B. 5.4 minutes D. 3.4 minutes 301. For a given line voltage, four heating coils will produce maximum heat when connected A. all in parallel B. all in series C. with two parallel pairs in series

D. one pair in parallel with the other two in series 302. Four heaters having the same voltage rating will produce maximum heat if connected in A. Series C. SeriesParallel B. Parallel D. ParallelSeries 303. to how many is ergs/sec. A. 2 x 1013 B. 1 x 1016

1000 kW is equal C. 1 x 1013 D. 2 x 1010

304. When current flows through heater coil, it glows but supply wiring does not glow because A. supply wiring is covered with insulation wiring B. current through supply line flows at slower speed C. supply wires are made of superior material D. resistance of heater coil is more than that of supply wire D. ELECTRIC CELLS 305. REE Board Exam October 1997 A load of 10 ohms was connected to a 12-volt battery. The current drawn was 1.18 amperes. What is the internal resistance of the battery? A. 0.35 ohm C. 0.25 ohm B. 0.20 ohm D. 0.30 ohm 306. REE Board Exam April 1997 The electromotive force of a standard cell is measured with a potentiometer that gives a reading of 1.3562 V. When a 1.0 megaohm resistor is connected across the standard cell terminals, the potentiometer reading drops to 1.3560 V, what is the internal resistance of the standard cell? A. 174.5 ohms C. 147.5 ohms B. 145.7 ohms D. 157.4 ohms 307. REE Board Exam April 1997 If a resistor rated at 5 watts and 6 volts are connected across a battery with an open circuit voltage of 6 volts. What is the internal resistance of the battery if the resulting current is 0.8 A?

A. 0.30 ohm B. 0.26 ohm

C. 0.23 ohm D. 0.03 ohm

308. REE Board Exam October 1998 A 12 V battery of 0.05-ohm resistance and another battery of 12 V and 0.075 ohm resistance supply power to a 2-ohm resistor. What is the current through the load? A. 5.85 A C. 5.72 A B. 5.63 A D. 5.91 A 309. REE Board Exam October 1996 The lead batteries “A” and “B” are connected in parallel. “A” has an open circuit voltage of 12 V and an internal resistance of 0.2 ohm. Battery “B” has an open circuit voltage of 12.2 V and an internal resistance of 0.3 ohm. The two batteries together deliver power to a 0.5 ohm power resistor. Neglecting effects of temperature, how much current is contributed by battery “A”? A. 29.62 A C. 12.85 A B. 16.00 A D. 25.24 A 310. EE Board Exam October 1981 A charger, a battery and a load are connected in parallel. The voltage across the charger is 12.5 volts and the battery has an emf of 12 volts and internal resistance of 0.1 ohm. The load consists of a 2 ohms resistor. Find the current through the charger. A. 6.61 A C. 6.42 A B. 6.25 A D. 6.50 A 311. REE Board Exam October 1996 A lead storage battery is rated at 12 volts. If the internal resistance is 0.01 ohm, what is the maximum power that can be delivered to the load? A. 1,200 W C. 7,200 W B. 3,600 W D. 1,800 W 312. EE Board Exam April 1995 A 120-V battery having an internal resistance of 0.5 ohm is connected through a line resistance of 0.5 ohms to a variable load resistor. What maximum power will the battery deliver to the load resistor? A. 36 watts C. 630 watts B. 63 watts D. 360 watts

313. REE Board Exam April 2002 A 12 volts battery has a 50 ampere-hour capacity. The internal resistance is 0.1 ohm. A 5 ohm load is connected for 5 hours. How many ampere-hours are still left? A. 28.51 C. 38.23 B. 41.24 D. 35.92 314. REE Board Exam April 2002 Two-24 volt battery supply power to a 20 ohm load. One battery has 0.2 ohm internal resistance while the other has 0.4 ohm. What power does the load draws? A. 28.4 W C. 30.8 W B. 22.2 W D. 18.6 W 315. ECE Board Exam March 1996 Which statement is not true? A. Secondary cell can be recharged B. The internal resistance of a cell limits the amount of output current C. The negative terminal of a chemical cell has a charge of excess electrons D. Two electrodes of the same metal provide the highest voltage output 316. ECE Board Exam November 2001 In the operation of dry cell we normally refer to the supply of current load resistance where its current neutralizes the separated charges at the electrodes. A. Aligning the cells B. Charging the cells C. Discharging the cells D. Polarizing the cells 317. ECE Board Exam November 2000 Refers to a power source or cell which can be rechargeable A. Battery C. Primary B. Secondary D. Storage 318. ECE Board Exam November 2001 In the operation of dry cell we normally refer to the supply of current load resistance where its current neutralizes the separated charge s at the electrodes. A. Aligning the cells B. Charging the cells C. Discharging the cells D. Polarizing the cells

B. Silver-zinc 319. ECE Board Exam November 2000 The part of the cell of the solution that acts upon the electrodes providing a path for electron flow A. Container C. Sealing way B. Electrolyte D. Electrolysis 320. ECE Board Exam April 1999 Type of cell used mostly for emergency equipment. It is light, small, and has a large capacity of power for its size. A. Ni-Cd cell C. Silver-zinc cell B. Silver-cadmium cell D. Mercury cell 321. ECE Board Exam March 1996 The purpose of cells connected in parallel is to_____. A. increase internal resistance B. increase in voltage output C. decrease current capacity D. increase in current capacity 322. ECE Board Exam November 1995 Find the output of a four (4) lead acid cells. A. 3.2 V C. 5.8 V B. 8.4 V D. 1.6 V 323. ECE Board Exam November 1997 How many silver zinc cells in series are needed for a 9V battery? A. 9 C. 3 B. 6 D. 7 324. ECE Board Exam November 1995 _____ is the specific gravity reading for a good lead acid cell. A. 1170 C. 1070 B. 1270 D. 1370 325. ECE Board Exam November 1998 Refers to a power source or cell that is not rechargeable? A. Secondary C. Storage B. Primary D. Battery 326. ECE Board Exam April 1998 Which of the following is not a primary type cell? A. Zinc-chloride C. Silver oxide

D. Carbon zinc

327. ECE Board Exam November 1997 A battery should not be charged or discharged at a high current in order to avoid this defect. A. Corrosion C. Buckling B. Sedimentation D. Sulphation 328. ECE Board Exam April 2001 It is a cell in which the chemical action finally destroys one of the electrons electrodes, usually the negative and cannot be recharged. A. Dry cell C. Wet cell B. Secondary cell D. Primary cell 329. ECE Board Exam November 2001 Which of the following statements is not true? A. Output of solar cell is normally 0.5 V B. Edison cell is storage type C. The Ni-Cd cell is primary type D. Primary cells can be charged 330. ECE Board Exam April 2001 Which of the following statements is not true? A. A primary cell has irreversible chemical reaction B. A carbon zinc cell has unlimited shelf life C. A storage cell has irreversible chemical reaction D. A lead acid cell can be recharged 331. ECE Board Exam November 1999 A device that transforms chemical energy into electrical energy A. Battery B. Cell C. Primary battery D. Secondary battery 332. ECE Board Exam April 1999 What is the effect of connecting battery cells in parallel? A. Current decreases B. Voltage increases C. Voltage decreases D. Current increases

333. ECE Board Exam November 1997 Determine how long a battery will last whose rating is 100 Ah, 24 volts and will run a 300 watts electronic equipment and a 50 watts light. A. 6.85 hours C. 26.65 hours B. 50.05 hours D. 12.00 hours 334. ECE Board Exam April 2001 The process of reversing the current flow through the battery to store the battery to its original condition A. Electrolysis C. Reverse flow B. Ionization D. Battery charge 335. ECE Board Exam November 2000 The type of cell commonly referred to as “flashlight battery” A. Nickel-cadmium battery C. Dry cell B. Mercury cell D. Lead acid cell 336. ECE Board Exam November 1998 How does a battery behave whose cells are connected in series? A. Increase current supply B. Reduces total voltage C. Increases voltage supply D. Reduces internal resistance 337. ECE Board Exam April 1998 Another very useful cell to solar cells however the junction is bombarded by beta particles from radioactive materials A. Alkaline cells C. Selenium cells B. Nucleus cells D. Lithium cells 338. ECE Board Exam November 2001 The continuation of current flow within the cell there is no external load A. Local action C. Selfdischarge B. Polarization D. Electrolysis 339. ECE Board Exam November 1998 Type of power source in electronics that cannot be recharged after it has delivered its rated capacity A. Cells B. Primary cells C. Battery D. Secondary cells

340. ECE Board Exam November 1995 Which has the largest diameter of the following dry cells? A. Type C C. Type AAA B. Type AA D. Type D 341. ECE Board Exam April 1998 How many nickel-cadmium cells are needed in series for a 10 V battery? A. 8 C. 5 B. 12 D. 10 342. ECE Board Exam March 1996 Current in a chemical cell refers to the movement of _____. A. Negative ions only B. Negative and positive ions C. Positive ions only D. Negative hole charge 343. ECE Board Exam November 1998 Find the output of a two (2) lead acid cells. A. 0.952 V C. 3.2 V B. 2.1 V D. 4.2 V 344. ECE Board Exam November 2000 The liquid solution that forms ion charges in a lead acid battery A. Electrolyte C. Sulfuric acid B. Hydrochloric acid D. Nitric acid 345. ECE Board Exam April 1998 Single device that converts chemical energy into electrical energy is called A. Battery C. Solar B. Generator D. Cell 346. ECE Board Exam November 1995 There are _____ identical cells in parallel needed to double the current reading of each cells. A. 3 C. 2 B. 4 D. 1 347. ECE Board Exam April 2001 What is the effect of connecting battery cells in series? A. Voltage increases

B. Current increases C. Voltage decreases D. Current decreases 348. ECE Board Exam November 2000 How long can a battery last with capacity of 50 ampere-hour running equipment of 5 amperes? A. 250 hours C. 100 hours B. 25 hours D. 10 hours 349. ECE Board Exam April 1998 How long will a battery need to operate a 240-watt equipment, whose capacity is 100 Ah and 24 volts rating? A. 10 hours C. 1 hour B. 5 hours D. 0.10 hour 350. ECE Board Exam November 2001 What is affected when a lead battery is overcharged? A. Carbon C. Plates B. Grid D. Electrolytes 351. ECE Board Exam November 1995 When the cells are in series voltages add, while current capacity is _____. A. The same as one cell B. Zero C. Infinite D. The sum of each cell 352. ECE Board Exam April 1999 Refers to an action in the operation of secondary cells reforming the electrodes in a chemical reaction where dc voltage is supplied externally. A. Polarizing cells B. Charging cells C. Aligning cells D. Discharging cells 353. ECE Board Exam November 1999 What type of cell that cannot be recharged which cannot restore chemical reaction? A. Primary cell B. Secondary cell C. Lead-acid wet cell D. Nickel-cadmium cell 354.

ECE Board Exam November 2000

An ordinary flashlight battery is which of the following? A. A load C. A storage cell B. A dry cell D. A wet cell 355. ECE Board Exam April 1998 Refers to dry storage cell carbon zinc. A. cell B. Edison cell C. Mercury cell D. Nickel cadmium cell 356. ECE Board Exam April 1998 What is the other term of the secondary cells considering its capability to accept recharging? A. Reaction cell C. Storage cell B. Primary cell D. Dry cell 357. ECE Board Exam November 1996 Find the required battery capacity needed to operate an equipment of 30 amperes at 5 hours. A. 6 C. 3 B. 30 D. 150 358. ECE Board Exam March 1996 When batteries have cells connected in series the effect is A. Reduced output voltage B. Increased current supply C. Increased voltage supply D. Reduced internal resistance 359. ECE Board Exam November 2000 Find the required battery capacity needed to operate on electronic equipment with power rating of 200 watts and 10 volts at 6 hours. A. 60 C. 20 B. 1200 D. 120 360. ECE Board Exam November 2000 A cell(s) that can be operated or used in a horizontal, vertical or any position where its electrolyte cannot be spilled in any position A. Primary cells C. Dry cells B. Secondary cells D. Battery 361. ECE Board Exam April 1999 It is an indication of the current supplying capability of the battery for a specific period of time, e.g. 400 ampere-hour.

A. Rating B. Capacity

C. Capability D. Current load

362. ECE Board Exam March 1996 Which of the following is not a secondary type cell? A. Lithium C. Silver cadmium B. Lead-acid D. Silver-zinc 363. ECE Board Exam March 1996 How many lithium cells in series are needed for a 12 V battery? A. 12 cells C. 8 cells B. 4 cells D. 10 cells 364. ECE Board Exam November 1996 Component of solar battery which uses light energy to produce electromagnetic force A. Alkaline cell C. Lithium cell B. Polymer cell D. Selenium cell 365. ECE Board Exam March 1996 If a dry cell has an internal resistance of 0.50 ohm and emf of 2 volts, find power delivered in a one ohm resistor. A. 1.33 watts C. 3.66 watts B. 1.66 watts D. 1.77 watts 366. ECE Board Exam March 1996 Parallel cells have the same voltage as one cell but have _____. A. Unstable resistance B. Less current capability C. Fluctuating power output D. More current capacity 367. ECE Board Exam April 1999 A battery with capacity of 100 Ah and 12 volts rating will run an electronic equipment at exactly 20 hours, how much power is needed? A. 60 watts C. 10 watts B. 20 watts D. 30 watts 368. ECE Board Exam March 1996 It is the output voltage of a carbon-zinc cell. A. 3.5 V C. 1.5 V B. 2.5 V D. 0.5 V

369. ECE Board Exam March 1996 What is the reason why more cells can be stored in a given area with dynamic cells? A. They consume less power B. They are smaller C. They are larger D. They travel faster 370. ECE Board Exam November 1997 A radio equipment will be used at 70% at 50 amperes rating for 5 hours. How much capacity of dry battery is needed? A. 35 C. 250 B. 17.5 D. 175 371. The potential at the terminals of the battery falls from 9 V on open circuit to 6 volts when a resistor of 10 ohms is connected across its terminals. What is the internal resistance of the battery? A. 5 Ω C. 3 Ω B. 4 Ω D. 2 Ω 372. A battery is formed of five cells joined in series. When the external resistance is 4 ohms, the current is 1.5 A and when the external resistance is 9 ohms, the current falls to 0.75 A. Find the internal resistance of each cell. A. 0.5 ohm C. 0.2 ohm B. 1.0 ohm D. 0.3 ohm 373.

A

12

V

source

with 0.05  resistance is connected in series with another 12 volt with 0.075 Ω resistance with a load of 2 . Calculate the power dissipated in the load. A. 365 watts C. 105 watts B. 127 watts D. 255 watts 374.

A

24

V

source

with 0.05  resistance is connected in parallel with another 24 V with 0.075  resistance to a load of 2 . Calculate the current delivered by the source with a 0.05  resistor. A. 7 amperes C. 5 amperes B. 10 amperes D. 12 amperes 375. A battery can deliver 10 joules of energy to move 5

coulombs of charge. What is the potential difference between the terminals of the battery? A. 2 V C. 0.5 V B. 50 V D. 5 V 376. An ordinary dry cell can deliver about ____ continuously. A. 3 A B. 2 A C. 1/8 A D. none of the above 377. Cells are connected in series when ____ is required. A. high voltage B. high current C. high voltage as well as high current D. none of the above 378. Cells are connected in series–parallel when ____ is required. A. high current B. high voltage C. high current as well a high voltage D. none of the above 379. Four cells, each of internal resistance 1 ohm, are connected in parallel. The battery resistance will be ____ A. 4 ohms C. 2 ohms B. 0.25 ohm D. 1 ohm 380. The e.m.f. of a cell depends upon ____ A. nature of electrodes and electrolyte B. size of electrodes C. spacing between electrodes D. none of the above 381. In order to get maximum current in series – parallel grouping, the external resistance should be ____ the total internal resistance of the battery. A. less than B. more than C. equal to D. none of the above

382. The positive terminal of a 6-V battery is connected to the negative terminal of a 12-V battery whose positive terminal is grounded. The potential at the negative terminal of the 6V battery is ____ volt. A. +18 C. -6 B. –12 D. -18 383. The positive terminal of a 6-V battery is connected to the negative terminal of a 12-V battery whose positive terminal is grounded. The potential at the positive terminal of the 6-V battery is ____ volt. A. +6 C. -12 B. -6 D. +12 384. of a lead-acid cell are A. lead peroxide B. sponge lead C. dilute sulfuric acid D. all of the above

Active

materials

385. During the charging of lead-acid cell A. its cathode becomes dark chocolate brown in colour B. its voltage increases C. it gives out energy D. specific gravity of H2SO4 is decreased 386. The ratio of Ah efficiency to Wh efficiency of a lead-acid cell is A. always less than one B. just one C. always greater than one D. either A or B 387. cell is measured in A. watt-hours B. watts hours

The capacity of a C. amperes D. ampere-

388. The capacity of a lead-acid cell does NOT depend on its A. rate of charge B. rate of discharge C. temperature

D. quantity of active materials 389. As compared to constant-current system, the constantvoltage system of charging a lead-acid cell has the advantage of A. avoiding excessive gassing B. reducing time of charging C. increasing cell capacity D. both B and C 390. Sulphation lead-acid battery occurs due to A. trickle charging B. incomplete charging C. heavy discharging D. fast charging 391. The materials of a nickel-iron battery are A. nickel hydroxide B. powdered iron and its oxides C. 21% solution of caustic potash D. all of the above

in

a

active

392. During charging and discharging of a nickel-iron cell A. its e.m.f. remains constant B. water is neither formed nor absorbed C. corrosive fumes are produced D. nickel hydroxide remains unsplit 393. As compared to a lead-acid cell, the efficiency of a nickel-iron cell is less due to its A. lower e.m.f. B. smaller quantity of electrolyte used C. higher internal resistance D. compactness 394. Trickle charging of a storage battery helps to A. prevent sulphation B. keep it fresh and fully charged C. maintain proper electrolyte level D. increase its reserve capacity 395. A dead storage battery can be revived by A. a dose of H2SO4 B. adding so-called battery restorer C. adding distilled water D. none of the above

396. The sediment which accumulates at the bottom of a leadacid battery consist largely of A. lead-peroxide B. lead-sulphate C. antimony-lead alloy D. graphite 397. The reduction of battery capacity at high rates of discharge is primarily due to A. increase in its internal resistance B. decrease in its terminal voltage C. rapid formation of PbSO4 on the plates D. non-diffusion of acid to the inside active materials 398. Floating system are widely used for A. power stations B. emergency lighting C. telephone exchange installation D. all of the above

battery

399. Any charge given to the battery when taken off the vehicle is called A. bench charge C. float charge B. step charge D. trickle charge 400. Storage battery electrolyte is formed by the dissolving of ____ acid in water. A. hydrochloric C. acetic B. sulfuric D. atric 401. The central terminal of a dry cell is said to be A. positive C. neutral B. negative D. charged 402. A 24 V battery of internal resistance r = 4 Ω is connected to a variable resistance R, the rate of heat dissipation in the resistor is maximum when the current drawn from the battery is I. Current drawn from the battery will be I/2 when R is equal to A. 8 Ω C. 16 Ω B. 12 Ω D. 20 Ω

403. What is the other term used for rechargeable battery? A. primary B. lead-acid C. storage D. nickel-cadmium E. NETWORK THEOREMS 404. REE Board Exam April 1997 A circuit consisting of three resistors rated: 10 ohms, 15 ohms and 20 ohms are connected in delta. What would be the resistance of the equivalent wye connected load? A. 0.30, 0.23 & 0.15 ohm B. 3.0, 4.0 & 5.0 ohms C. 3.33, 4.44 & 6.66 ohms D. 5.77, 8.66 & 11.55 ohms 405. EE Board Exam October 1994 The equivalent wye element of a 3 equal resistors each equal to R and connected in delta is A. R C. R/3 B. 3R/2 D. 3R 406. EE Board Exam April 1988 A Barangay power station supplies 60 kW to a load over 2,500 ft, 100 mm2, two-conductor copper feeder, the resistance of which is 0.078 ohm per 1000 ft. The bus bar voltage is maintained constant at 600 V. Determine the load current. A. 105 A C. 110 A B. 108 A D. 102 A 407. EE Board Exam October 1986 An LRT car, 5 km distance from the Tayuman station, takes 100 A over a 100 mm hard drawn copper trolley wire having a resistance of 0.270 ohm per km. The rail and ground return has a resistance of 0.06 ohm per km. If the station voltage is 750 V, what is the voltage of the car? A. 585 V C. 595 V B. 590 V D. 580 V 408. EE Board Exam April 1989 The LRT trolley system 10 miles long is fed by two substations that generate 600 volts and 560 volts, respectively. The resistance of the trolley wire and rail return is 0.3 ohm per mile. If the car is located 4 miles from the

600 volt station draws 200 A from the line. How much is the current supplied by each station? A. 133.33 A, 66.67 A B. 123.67 A, 76.33 A C. 117.44 A, 82.56 A D. 125.54 A, 63.05 A 409. EE Board Exam April 1992 In Manila, the LRT runs between Gil Puyat Station and Tayuman Station, which is 4 km apart and maintains voltages of 420 volts and 410 volts respectively. The resistance of go and return is 0.05 ohm per km. The train draws a constant current of 300 A while in motion. What are the currents supplied by the two stations if the train is at the distance of minimum potential? A. 175 A, 125 A C. 164 A, 136 A B. 183 A, 117 A D. 172 A, 123 A 410. EE Board Exam October 1986 An LRT car, 5 km distance from the Tayuman station, takes 100 A over a 100 mm hard drawn copper trolley wire having a resistance of 0.270 ohm per km. The rail and ground return has a resistance of 0.06 ohm per km. If the station voltage is 750 V, what is the efficiency of transmission? A. 78% C. 74% B. 81% D. 79% 411. EE Board Exam April 1988 A barangay power station supplies 60 kW to a load over 2,500 ft of 0002-conductor copper feeder the resistance of which is 0.078 ohm per 1,000 ft. The bus bar voltage is maintained constant at 600 volts. Determine the maximum power which can be transmitted. A. 220.35 kW C. 242.73 kW B. 230.77 kW D. 223.94 kW 412. EE Board Exam April 1991 Twelve similar wires each of resistance 2 ohms are connected so as to form a cube. Find the resistance between the two diagonally opposite corners. A. 1.45 ohms C. 2.01 ohms B. 1.66 ohms D. 1.28 ohms 413.

EE Board Exam April 1991

Twelve similar wires each of resistance 2 ohms are connected so as to form a cube. Find the resistance between the two corners of the same edge. A. 1.133 ohms C. 1.125 ohms B. 1.102 ohms D. 1.167 ohms 414. EE Board Exam October 1991 Twelve identical wires each of resistance 6 ohms are arranged to form the edge of a cube. A current of 40 mA is led into the cube at one corner and out at the other diagonally opposite corners. Calculate the potential difference developed between these corners. A. 0.20 V C. 0.22 V B. 0.28 V D. 0.24 V

A. 182.41 V B. 153.32 V

C. 164.67 V D. 157.22 V

418. EE Board Exam October 1980, April 1984 In the dc circuit as shown, the high resistance voltmeter gives a reading of 0.435 volt. What is the value of the resistance R?

415. EE Board Exam August 1976 Find the value of the voltage V.

A. 12.34 V B. 11.24 V

C. 12.19 V D. 11.66 V

416. EE Board Exam April 1982 Referring to the circuit diagram below, if the charger voltage is 130 volts and the battery voltage is 120 volts, solve for the current Ib.

A. 4 ohms B. 5 ohms

419. EE Board Exam April 1980 Determine I in the figure.

A. 0.028 A B. 0.010 A A. -0.215 A B. 0.215 A

C. -0.306 A D. 0.306 A

417. EE Board Exam August 1977 In the figure below R1 = 1 ohm, R2 = 1 ohm, R3 = 3 ohms, I2 = 2 A and VB = 120 V. Find Eg.

C. 3 ohms D. 2 ohms

C. 0.025 A D. 0.014 A

420. ECE Board Exam April 1999 In Kirchhoff’s current law, which terminal of a resistance element is assumed to be at a higher potential (more positive) than the other? A. The terminal where the current exits the resistance elements B. The terminal where the current enters the resistance elements C. Either A or B can be arbitrarily selected

D. The terminal closest to the node being analyzed

B. 40 ohms

D. 4 kohms

421. ECE Board Exam April 2000 According to Kichhoff’s current law, what is the algebraic sum of all currents entering and exiting a node. A. zero B. a negative value C. the algebraic sum of all currents D. a positive value

427. ECE Board Exam November 1995 In order to match the load to the generator means making load resistance ______. A. lower than generator’s internal resistance B. increased to more generator’s internal resistance C. decreased D. equal to generator’s internal resistance

422. ECE Board Exam November 1997 Find the Thevenin’s impedance equivalent across R2 of a linear close circuit having 10 volts supply in series with the resistors (R1 = 100 ohms and R2 = 200 ohms). A. 6.66 ohms C. 66.6 ohms B. 6.666 kohms D. 666 ohms

428. A circuit contains a 5 A current source in parallel with an 8 ohm resistor. What is the Thevenin’s voltage and Thevenin’s resistance of the circuit? A. 40 V, 8  C. 5 V, 8 

423. ECE Board Exam April 1999 What is a node? A. A terminal point for a loop current B. A connection point between two or more conductors C. A formula D. A mathematical fiction

429. In the Norton’s equivalent circuit, the source is a A. constant voltage source B. constant current source C. constant voltage, constant current D. none of these

424. ECE Board Exam November 1998 If a resistance element is part of two loops, how many voltage drops must be calculated for that component? A. Two C. One B. Three D. None 425. ECE Board Exam April 1998 How many nodes are needed to completely analyze a circuit according to Kirchhoff’s current law? A. One B. Two C. One less than the total number of nodes in the circuit D. All nodes in the circuit 426. ECE Board Exam November 1996 Find the Thevenin’s impedance equivalent across R2 of a linear close circuit having 10 volt supply in series with two resistors (R1=50 ohms and R2 = 200 ohms). A. 400 ohms C. 4 ohms

B. 5/8 V, 40 

D. 5/8 V, 8 

430. The superposition theorem requires as many circuits to be solved as there are A. meshes B. source C. nodes D. all of the above 431. Three resistors of 6-ohm resistance are connected in delta. Inside the delta another 6-ohm resistors are connected in wye. Find its resistance between any two corners. A. 2 ohms C. 4 ohms B. 3 ohms D. 1 ohm 432. A 2-wire dc distribution line has sending end voltage of 240 V and total line resistance of 0.4 ohm. The maximum kW that can be transmitted by the line is ____. A. 108 C. 36 B. 72 D. 144

433. An active element in a circuit is one which ____. A. receives energy B. supplies energy C. both receives and supplies energy D. none of the above

A. B. C. D.

three four two none of the above

439. The circuit shown in Fig. 3.1 has ____ branches.

434. An passive element in a circuit is one which ____. A. supplies energy B. receives energy C. both receives and supplies energy D. none of the above 435. An electric circuit contains ____. A. active elements only B. passive element only C. both active and passive elements D. none of the above 436. A linear circuit is one whose parameters (e.g. resistances etc.) ____. A. change with change in current B. change with change in voltage C. do not change with change in voltage and current D. none of the above 437. In the circuit shown in Fig. 3.1, the number of nodes is ____

A. B. C. D.

two four three none of the above

440. in Fig. 3.1 has ____ loops.

A. B. C. D.

The circuit shown

two four three none of the above

441. In the circuit shown in Fig. 3.1, there are ___ meshes.

A. one B. two

C. three D. four

438. In the circuit shown in Fig. 3.1, there are ____ junctions.

A. B. C. D.

two three four none of the above

442. To solve the circuit shown in Fig. 3.2 by Kirchhoff’s laws, we require ____

A. B. C. D.

A. one equation equations B. two equations equations

C. three D. four

one equation three equations two equations none of the above

446. In the circuit shown in Fig. 3.3, the voltage at node B wrt D is calculated to be 15 V. The current in the 3 Ω resistor will be

443. To solve the circuit shown in Fig. 3.2 by nodal analysis, we require ____

A. B. C. D. A. B. C. D.

one equation two equation three equations none of the above

2A 5A 2.5 A none of the above

447. The current in 2 Ω horizontal resistor in Fig. 3.3 is ____.

444. To solve the circuit shown in Fig. 3.2 by superposition theorem, we require ____ A. 10 A B. 5 A

C. 2 A D. 2.5 A

448. In order to solve the circuit shown in Fig. 3.3 by nodal analysis, we require A. B. C. D.

one circuit two circuits three circuits none of the above

445. To solve the circuit shown in Fig. 3.2 by Maxwell’s mesh current equation, we require

A. B. C. D.

one equation two equation three equations none of the above

449. The superposition theorem is used when the circuit contains A. a single voltage source

B. a number of passive source C. passive elements only D. none of the above 450. Fig. 3.4(b) shows the Thevenin’s equivalent circuit of Fig. 3.4(a). The value of Thevenin’s voltage Vth is ____.

A. 3.5 Ω B. 6.4 Ω

C. 7.4 Ω D. 15 Ω

454. Fig. 3.5(b) shows Norton’s equivalent circuit of Fig. 3.5(a). The value of RN is ____.

A. 20 V B. 24 V 451. in Fig. 3.4(b) is ____.

C. 12 V D. 36 V The value of Rth

A. B. C. D.

A. 15 Ω B. 3.5 Ω

C. 6.4 Ω D. 7.4 Ω

5Ω 4.5 Ω 10.5 Ω none of the above

455. Fig. 3.5(b) is ____.

The value of IN in

452. The opencircuited voltage at terminals AB in Fig. 3.4(a) is

A. B. C. D. A. 12 V B. 20 V

C. 24 V D. 40 V

453. For transfer of maximum power in the circuit shown in Fig. 3.4(a), the value of RL should be ____.

3A 1A 2A none of the above

456. Thevenin’s theorem is ____ form on an equivalent circuit. A. voltage B. current C. both voltage and current D. none of the above 457. Norton’s theorem is ____ Thevenin’s theorem. A. the same as

B. converse of C. equal to D. none of the above 458. In the analysis of a vacuum tube circuit, we generally use ____. A. superposition C. Thevenin’s B. Norton’s D. reciprocity 459. Norton’s theorem is ____ form of an equivalent circuit A. voltage B. current C. both voltage and current D. none of the above 460. In the analysis of a transistor circuit, we generally use ____. A. Norton’s C. reciprocity B. Thevenin’s D. superposition 461. Fig. 3.6(a) shows Norton’s equivalent circuit of a network whereas Fig. 3.6(b) shows its Thevenin’s equivalent circuit. The value of Vth is ____.

A. B. C. D.

1V 9V 5V none of the above

464. For maximum power transfer, the relation between load resistance RL and internal resistance R i of the voltage source is ____. A. RL = 2Ri C. RL = 1.5Ri B. RL = 0.5Ri D. RL = Ri 465. Under the conditions of maximum power transfer, the efficiency is ____. A. 75% C. 50% B. 100% D. 25% 466. The opencircuited voltage at terminals of load R L is 30 V Under the conditions of maximum power transfer, the load voltage would be ____. A. 30 V C. 5 V B. 10 V D. 15 V

A. 1.5 V B. 0.866 V 462. in Fig. 3.6(b) is ____.

A. 3 Ω B. 2 Ω

C. 3 V D. 6 V The value of Rth

C. 1.5 Ω D. 6 Ω

463. If in Fig. 3.6(a), the value of IN is 3 A, then value of Vth in Fig. 3.6(b) will be ____.

467. The maximum power transfer theorem is used in ____. A. electronic circuits B. power system C. home lighting circuits D. none of the above 468. Under the conditions of maximum power transfer, a voltage source is delivering a power of 30 W to the load. The power generated by the source is ____. A. 45 W C. 60 W B. 30 W D. 90 W 469. For the circuit shown in Fig. 3.7, the power transferred will be maximum when RL is equal to ____.

473. The output resistance of a voltage source is 4 Ω. Its internal resistance will be ____. A. 4 Ω C. 1 Ω B. 2 Ω D. infinite A. B. C. D.

4.5 Ω 6Ω 3Ω none of the above

470. The opencircuited voltage at terminals AB in Fig. 3.7 is ____.

474. Delta/star of star/delta transformation technique is applied to ___. A. one terminal B. two terminal C. three terminal D. none of the above 475. Kirchhoff’s current law is applicable to only A. closed loops in a network B. electronic circuits C. conjunctions in a network D. electric circuits

A. 12 V B. 6 V

C. 15 V D. 9.5 V

471. If in Fig. 3.7, the value of RL = 6 Ω, then current through R L is ____.

A. 2 A B. 1.5 A

C. 1.75 A D. 1 A

472. Under the conditions of maximum power transfer, the voltage across RL in Fig. 3.7 is ____.

A. 6 V B. 4 V

C. 9 V D. 12 V

476. Kirchhoff’s voltage law is concerned with A. IR drops B. battery e.m.f.s. C. junction voltages D. both A and B 477. According to KVL, the algebraic sum of all IR drops and e.m.f.s in any closed loop of a network is always A. zero B. positive C. negative D. determined by the battery e.m.f.s 478. The algebraic sign of an IR drop is primarily dependent upon the A. amount of current flowing through it B. value of R C. direction of current flow D. battery connection 479. Maxwell’s loop current method of solving electrical networks A. uses branch currents B. utilizes Kirchhoff’s voltage law C. is confined to single-loop circuits D. is a network reduction method

480. Point out the WRONG statement. In the node-voltage technique of solving networks, choice of a reference node does not A. affect the operation of the circuit B. change the voltage across any element C. alter the p.d. between any pair of nodes D. affect the voltages of various nodes

A. replaced by “opens” B. replaced by “shorts” C. treated in parallel with other voltage sources D. converted into equivalent voltage sources 487. Thevenin resistance of the circuit of Fig. 2.1 across its terminals A and B is ____ ohm.

481. The nodal analysis is primarily based on the application of A. KVL C. Ohm’s Law B. KCL D. both B and C 482. Superposition theorem is can be applied only to circuits having ____ elements. A. non-linear C. linear bilateral B. passive D. resistive

Fig. 2.1 A. 6 B. 3

C. 9 D. 2

488. The load resistance needed to extract maximum power from the circuit of Fig. 2.2 is ____ ohm.

483. The Superposition theorem is essentially based on the concept of A. duality C. reciprocity B. linearity D. non-linearity 484. While Thevenizing a circuit between two terminals, Vth equals A. short-circuit terminal voltage B. open circuit terminal voltage C. EMF of the battery nearest to the terminal D. net voltage available in the circuit 485. Thevenin resistance Rth is found A. between any two “open” terminals B. by short-circuiting the given two terminals C. by removing voltage sources along with their internal resistance D. between same open terminals as for Vth 486. While calculating Rth, constant-current sources in the circuit are

Fig. 2.2 A. 2 B. 9

C. 6 D. 18

489. The Norton equivalent circuit for the network of Fig. 2.2 between A and B is ____ current source with parallel resistance of ____.

Fig. 2.2 A. 2 A, 6 Ω B. 3 A, 2 Ω

C. 2 A, 3 Ω D. 3 A, 9 Ω

490. The Norton equivalent of a circuit consists of a 2 A current source in parallel with a 4  resistor. Thevenin equivalent of this circuit is a ____ volt source in series with a 4  resistor. A. 2 C. 6 B. 0.5 D. 8 491.

If two identical 3

A, 4  Norton equivalent circuits are connected in parallel with like polarity to like, the combined Norton equivalent circuit is A. 6 A, 4  C. 3 A, 2 Ω B. 6 A, 2 

D. 6 A, 8 Ω

492. Two 6 V, 2  batteries are connected in series aiding. This combination can be replaced by a single equivalent current generator of ____ with a parallel resistance of ____ ohm. A. 3 A, 4  C. 3 A, 1 Ω B. 3 A, 2 

D. 5 A, 2 Ω

493.

Two identical 3 A,

1  batteries are connected in parallel with like polarity with like polarity to like. The Norton equivalent circuit of the combination is A. 3 A, 0.5  C. 3 A, 1 Ω B. 6 A, 1 

496. A 12 volt source with an internal resistance of 1.2 ohms is connected across a wire-wound resistor. Maximum power will be dissipated in the resistor when its resistance is equal to A. zero C. 12 ohms B. 1.2 ohm D. infinity 497. Three 3.33  resistors are connected in wye. What is the value of the equivalent resistors connected in delta? A. 3.33  C. 6.67  B. 10 

D. 20 

498. Find the equivalent resistance between terminals a & b of the circuit shown. Each resistance has a value of 1 ohm.

D. 6 A, 0.5 Ω

494. Thevenin equivalent circuit of the network shown in Fig. 2.3 is required. The value of the opencircuit voltage across terminals a and b of this circuit is ____ volt.

A. zero B. 2i/10

C. 2i/5 D. 2i/15

containing

For a generators

A. 5/6 ohms B. 5/11 ohms

C. 5/14 ohms D. 5/21 ohms

499. What do you call the head to tail connection of two or more op-amp circuits wherein the output of one op-amp is the input of another op-amp? A. Parallel Op-Amps B. Follow-Thru Connection C. Cascade Connection D. Series Op-Amps

Fig. 2.3

495. network

impedance, the ratio of the voltage to the current produced in other loop is the same as the ratio of voltage and current obtained when the positions of the voltage source and the ammeter measuring the current are interchanged. This network theorem is known as ____ theorem. A. Millman’s C. Tellegen’s B. Norton’s D. Reciprocity

linear and

500. Find the power dissipation in the 6 ohms resistor in the next figure.

A. 54 W B. 216 W

C. 121.5 W D. 150 W

501. Determine the value of node voltage V2. All resistances are in ohms.

A. 14 V B. 12 V

C. 0 V D. 1 V

502. What should be the value of R so the resistor will receive the maximum power? All resistances are in ohms.

A. 10.0 ohms B. 3.875 ohms

C. 0.968 ohms D. 1.60 ohms

503. Determine the value VO in the ideal op-amp circuit below.

A. -8 V B. -6 V

C. -4 V D. -3 V

504. Determine value VO in the op-amp circuit below.

the

A. -4 V B. -8 V

C. -2 V D. -3 V

505. If the voltage source (dependent or independent) is connected between two non-reference nodes, the two non-reference nodes form a ______ A. Common Node B. Supernode C. Complex Node D. Reference node 506. The theorem that states that “the voltage across or current through an element in a linear circuit is the algebraic sum of the voltages across or current through that element due to each independent source acting alone”. A. Superposition Theorem B. Thevenin’s Theorem C. Norton’s Theorem D. Reciprocity Theorem 507. Kirchhoff’s Current Law states that A. the algebraic sum of the currents flowing into any point in a circuit must equal zero B. the algebraic sum of the currents entering and leaving any point in a circuit must equal zero C. the algebraic sum of the currents flowing away from any point in a circuit must equal zero D. the algebraic sum of the currents around any closed path must equal zero 508. When applying Kirchhoff’s Current Law, A. consider all the currents flowing into a branch point positive and all currents directed away from that point negative B. consider all the currents flowing into a branch point negative and all currents directed away from that point positive

C. remember that the total of all the currents entering a branch point must always be greater than the sum of the currents leaving that point D. the algebraic sum of the currents entering and leaving a branch point does not necessarily have to be zero 509. Kirchhoff’s Voltage Law, commonly referred to as a A. node B. principal node

When applying a closed path is C. loop D. branch point

510. Kirchhoff’s Voltage Law states that A. the algebraic sum of the voltage sources and IR voltage drops in any closed path must total zero B. the algebraic sum of the voltage sources and IR voltage drops around any closed path can never equal zero C. the algebraic sum of all the currents flowing around any closed path must equal zero D. none of the above 511. When applying Kirchhoff’s Voltage Law A. consider any voltage whose positive terminal is reached first as negative and any voltage whose negative terminal is reached first as positive B. always consider all voltage sources as positive and all resistor voltage drops as negative C. consider any voltage whose negative terminal is reached first as negative and any voltage whose positive terminal is reached first as positive D. always consider all resistor voltage drops as positive and all voltage sources as negative 512. The algebraic sum of +40 V and -30 V is A. -10 V C. +70 V B. +10 V D. -70 V 513. is A.

A principal node

a closed path or loop where the algebraic sum of the voltages must equal zero B. the simplest possible closed path around a circuit C. a junction where branch current can combine or divide D. none of the above

514. How many equations are necessary to solve a circuit with two principal nodes? A. 3 C. 4 B. 2 D. 1 515. The difference between a mesh current and a branch current is A. a mesh current is an assumed current and a branch current is an actual current B. the direction of the current themselves C. a mesh current does not divide at a branch point D. both A and B above 516. Using the method of mesh currents, any resistance common to two meshes has A. two opposing mesh currents B. one common mesh current C. zero current D. none of the above 517. The fact that the sum of the resistor voltage drops equals the applied voltage in a series circuit is the basis for A. Kirchhoff’s Current Law B. node voltage analysis C. Kirchhoff’s Voltage Law D. the method of mesh currents 518. The fact that the sum of the individual branch currents equals the total current in a parallel circuit is the basis for A. Kirchhoff’s Current Law B. node voltage analysis C. Kirchhoff’s Voltage Law D. the method of mesh currents 519. If you do not go completely around the loop when applying Kirchhoff’s Voltage Law, then A. the algebraic sum of the voltages will always be positive B. the algebraic sum is the voltage between the start and finish points C. the algebraic sum of the voltages will always be negative D. the algebraic sum of the voltages cannot be determined 520. example of a(n) A. bilateral component B. active component C. passive component D. both A and C

A resistor is an

521. To apply Superposition theorem, all components must be A. the active type B. both linear and bilateral C. grounded D. both nonlinear and unidirectional 522. When converting from a Norton-equivalent circuit to a Thevenin equivalent circuit or vice versa A. RN and RTH have the same value B. RN will always be larger than RTH C. IN is shorted-circuit to find VTH D. VTH is short-circuited to find IN 523. When solving for the Thevenin equivalent resistance, RTH, A. all voltage sources must be opened B. all voltage sources must be shortcircuited C. all voltage sources must be converted to current sources D. none of the above 524. Thevenin’s Theorem states that an entire network connected to a pair of terminals can be replaced with A. a single current source in parallel with a single resistance B. a single voltage source in parallel with a single resistance C. a single voltage source in series with a single resistance D. a single current source in series with a single resistance

527. With respect to terminals A and B in a complex network, the Norton current, IN, is A. the current flowing between terminals A and B when they are open B. the total current supplied by the applied voltage to the network C. zero when terminals A and B are shortcircuited D. the current flowing terminals A and B when they are short-circuited 528. Which theorem provides a shortcut for finding the common voltage across any number of parallel branches with different sources? A. The Superposition Theorem B. Thevenin’s Theorem C. Norton’s Theorem D. Millman’s Theorem 529. A d.c. usually has ____ as the load A. Resistance B. Capacitance C. Inductance D. both inductance and capacitance

circuit

530. Electrical appliances are connected in parallel because it ____ A. is a simple circuit B. draws less current C. results in reduce in power loss D. makes the operation of appliances independent of each other

525. Norton’s Theorem states that an entire network connected to a pair of terminals can be replaced with A. a single current source in parallel with a single resistance B. a single voltage source in parallel with a single resistance C. a single voltage source in series with a single resistance D. a single current source in series with a single resistance

531. The purpose load in an electric circuit is to ____ A. increase the circuit current B. utilize electrical energy C. decrease the circuit current D. none of the above

526. With respect to terminals A and B in a complex network, the Thevenin voltage, VTH, is A. the voltage across terminals A and B when they are short-circuited B. the open-circuit voltage across terminals A and B C. the same as the voltage applied to the complex network D. none of the above

C. neither emf nor current source D. none of these

532. network has A. no emf source B.

A

of

passive

no current source

533. The relationship between voltage and current is the same for two opposite directions of current in case of A. bilateral network B. active network C. unilateral network D. passive network

534. Which of the following statement is not correct? A. voltage source is an active element B. current source is a passive element C. resistance is a passive element D. conductance is a passive element 535. A resistance R is connected across two batteries, A and B connected in parallel. The open circuit emfs and internal resistances of the batteries are 12 V, 2 ohms and 8 V, 1 ohm respectively. Determine the ohmic value of R if the power absorbed by R is 7.656 watts. A. 10  C. 9  B. 12 

D. 8 

536. A network has 7 nodes and 5 independent loops. The number of branches in the network is A. 13 C. 11 B. 12 D. 10 537. The nodal method of circuit analysis is based on A. Kirchhoff’s Voltage Law & Ohm’s law B. Kirchhoff’s Current Law & Ohm‘s law C. Kirchhoff’s Current Law & Kirchhoff’s Voltage Law D. Kirchhoff’s Current Law & Kirchhoff’s Voltage Law & Ohm‘s law

C. b - n + 1 D. independent no. of nodes 541. The following constitutes a bilateral element A. Resistor C. Vacuum Tube B. FET D. metal rectifier 542. fail A. B. C. D.

Kirchhoff’s Laws in the case of linear networks non-linear networks dual networks distributed parameter networks

543. Ohm’s law, Kirchhoff’s Current Law & Kirchhoff’s Voltage will fail at A. Low frequency C. high power B. high frequency D. none of these 544. Total no, of mesh equations required is equal to A. number of links B. number of tree branches C. number of nodes D. none of these 545. The minimum number of equations required to analyze the circuit

538. For a network of seven branches and four nodes, the number of independent loops will be A. 11 C. 7 B. 8 D. 4 539. A network has b branches and nodes. For this mesh analysis will be simpler then node analysis if n is greater then A. b C. (b/2) + 1 B. b + 1 D. b/2 540. The number of independent loops for a network with n nodes and b branches is A. n - 1 B. b - n

A. 3 B. 4

C. 6 D. 7

546. Equivalent impedance seen across terminals a, b is

A. 16/3 Ω B. 8/3 Ω

C. 8/3 + j12 D. none of these

547. What is the Rab in the circuit when all resistors values are R?

A. R B. 2R

551. Find the resistance Rin is in the circuit shown .

A. A. 2R B. R

Find

1+ √ 3

Rab.

(1−√ 5)/2

C.

D. none of these

All 552. of i1?

A. 0 B. –6 A. 22.5 B. 40

total

(−1+ √5)/2

C. R/2 D. 3R

B. 548. values are in ohms.

C. 3R D. 4R

C. 30 D. none of these

553. circuit shown.

What is the value

C. 6 D. none of these Find

Ix

in

the

549. Find the equivalent resistance of the circuit in the figure.

A. 3A B. –3 A 554. the given circuit. A. 3 ohms B. 4 ohms

C. 0 D. none of these Find value of R in

C. 5 ohms D. 6 ohms

550. Find the equivalent resistance of the circuit in this figure.

A. 8.2 Ω B. 6 Ω

C. 10 Ω D. none of these

555. The voltage V in the figure always equal to

A.

42.2 V

C. 97.3

V B. 83.3 V

A. 9 V B. 5 V these

C. 1 V D. none

556. circuit shown.

Find

V

560. the fig shown.

557. circuit shown.

in

the A. 2 V B. 4/3 V

558. circuit shown.

A. + 3 V B. – 3 V 559. this circuit

C. 4 V D. 8 V Find

VX

in

the

C. 1 V D. none of these Find

V

in

the

A. 2.5 V B. -2.5 V 562. the fig shown

A. – 3 V B. +3 V

Find voltage eo in

of

561. circuit shown A. 2 V B. 3 V

D. 103V

C. 2 V D. none of these Find

V

in

the

A. 48 V B. 24 V 563. is

C. 0 V D. 10 V Find voltage eo in

C. 36 V D. 28 V The voltage v(t)

C. 2 V D. none of these Determine VX of

A. eat – e-bt B. eat + ebt 564. through 5 Ω resistor

A.

0

C. aeat – bebt D. aeat + bebt Find

C. 3 A

current

B. 2 A 565.

A. 10 V B. 46 V 566.

A. 3V B. 54V 567.

D. 7 A

569. figure shown.

Find

i2

in

the

Find Vxy

C. 13 V D. 58 V What is VAB?

C. 24 V D. none of these What is Vxy?

A. 4 A B. 2/3 A

C. -2/3A D. none of these

570. When a resistor R is connected to a current source, it consumes a power of 18 W. When the same R is connected to a voltage source having same magnitude as the current source, the power absorbed by R is 4.5 W. The magnitude of the current source & value of R are A.

√ 18

A & 1 ohm

ohms B. 3 A & 2 ohms ohms

C. 1

A

&

18

D. 6

A

&

0.5

571. In the circuit shown in the figure. If I = 2, then the value of the battery voltage V will be

A. 20 V B. 30 V

C. –10 V D. 10 V

568. In the circuit of the given figure. The value of the voltage source E is

A. 5 V B. 3 V 572. figure shown.

A. B. C. D.

A. –16 V B. 4 V

C. –6 V D. 16 V

C. 2 V D. 1 V Find E and I in the

I = 13 A and E = 31 V I = 31 A and E = 13V E = 31 V and I = 31A none of these

573. Find the voltage across the terminals a and b.

A. 0.5 V B. 3.0 V

C. 3.5 V D. 4.0 V

A. 1 A B. 2 A

574. What is the current supplied by 1 V source when each resistance is 1 ohm?

578. In the circuit shown in the given figure, the potential difference V2 – V1 is

A. –4.5 V B. 0

A.

8/15 A

579. figure shown.

C. 4/15

A B. 15/4 A 575. equal to

Find

V

in

the

The voltage V is

580.

C. 40 V D. none of these What is VA?

C. 5 V D. none of these

576. The across 15 ohms resistor is

voltage

A. -2 V B. 2 V A. -105 V B. +105 V

C. 4.5 V D. 6 V

D. none of these

A. 56.25 V B. 85 V

A. 3 V B. –3 V

C. 4 A D. 8 A

C. –15 V D. + 15 V

577. In the circuit of the given figure. The current I will be

581. of I4 in the fig shown?

C. -4 V D. 4 V What is the value

A. 1 A B. 4/3 A A. B. C. D.

–4 A –2 A known only if V1, V2 and R are known known only if V1, V2 are known

582. If the voltage of each source in the given network is doubled, then which of the following statement would be true?

C. 2 A D. 3 A

585. Find the value of R for which the power supplied by the voltage source is zero.

A. 0 B. 1.5 ohms

C. 6 ohms D. 0.667 ohms

586. What value of R which ensures that the current through the 60 ohm resistor of this circuit is 1 A? 1. Current flowing doubled 2. Voltages across doubled 3. Power absorbed doubled 4. Power delivered doubled A. 1, 2, 3, 4 B. 1, 2

in the network will be each resistor will be by each resistor will be



by each source will be C. 2, 3 D. 1, 3, 4

583. For a given network, the number of independent mesh equation (Nm) and the number of independent node equation (Nn) obey the following: A. Nm = Nn B. Nm > Nn C. Nm < Nn D. any one of the above, depending on the network

587. the circuit of the figure is

A. 2 A B. 1.5 A

The current I in

C. 0.5 A D. 0 A

588. In the shown in the given figure, current I is

584. In the circuit of the given figure. What is the current I?

A. –2/5 B. 24/5

C. 18/5 D. 2/5

circuit

589. A 35 V source is connected to a series circuit of 600Ω and R as shown. If a voltmeter of internal resistance1.2 kΩ is connected across 600 Ω resistor it reads 5 V, find the value of R.

A. 1.2 kΩ B. 2.4 kΩ 590. in RL in the circuit below.

A. 0 B. 2/3

B. Voltage source of 25 V with +ve terminal downward C. Current source of 2 A upward D. Current source of 2A downward 593. In the circuit shown in the figure. The effective resistance faced by the voltage source is

C. 3.6 kΩ D. 7.2 kΩ

A. 1 Ω B. 2 Ω

Find the current

C. 3 Ω D. 3.3 Ω

594. If a resistance ‘R’ of 1Ω is connected across the terminals AB as shown in the given fig. Then the current flowing through R will be

C. 1/3 D. none

591. The current flowing through the voltage source in the given circuit is

A. 1 A B. 0.5 A

C. 0.25 A D. 0.125 A

595. Find VL across the ¼ ohm resistor of this circuit.

A. 1.0 A B. 0.75 A

C. 0.5 A D. 0.25 A

592. In the circuit shown, the voltage across 2Ω resistor is 20 V. The 5 Ω resistor connected between the terminals A and B can be replaced by an ideal

A.

1/52 V

C. 3/52

B. 2/52 V

D. 5/52

V

596. shown

A.

Voltage source of 25 V with +ve terminal upward

V

Find Ix in the fig

A. 1 A B. –2 A

C. 2 A D. none of these

597. A particular resistor R dissipates a power of 4W when V alone is active. The same resistor R dissipates a power of 9 watts when I alone is active. The power dissipated by R when both sources are active will be

is open. If the ends ab were shorted, the current drawn would be

A. ∞ B. 4I

C. 2I D. I

602. In the figure below, the voltage across the 18 ohm resistor is 90 volts. What is the total voltage across the combined circuit? A. 1 W B. 5 W

C. 13 W D. 25 W

598. The linear network contains only resistors if is1 = 8A, is2 = 12A, Vx is found to be 80v. If i s1 = -8A, is2 = 4A, Vx = 0 . Find Vx when is1 = is2 = 20A. A. 125 V B. 16 V

A. –150 B. 150

C. 100 D. 50

C. 24 V D. 40 V

603. Find the current transfer ratio I2/I1 for the network shown in the figure. All resistors are given as 2 ohms.

599. When R = 10 ohms, VR = 20 V, when R = 20 ohms V R = 30 V. Find VR when R = 80 ohms. A. 0.25 B. 0.40 A. 40 B. 160 600.

A. 4 V, 8 V B. 8 V, 4 V

C. 48 D. none

C. 0.50 D. 0.75

604. In the network shown in the given figure, the effective resistance faced by the voltage source is

Find V1 & V2.

C. 6 V, 6 V D. 12 V, 12 V

601. The network shown in the figure draws current I when ab

A. 4 ohms B. 3 ohms

C. 2 ohms D. 1 mega ohms

605. The V-I relation for the network shown in the given box is V = 4I - 9. If now a resistor R = 2 ohms is connected across it, then the value of I will be

A. –4.5 A B. –1.5 A

C. 1.5 A D. 4.5 A

606. In the circuit shown in the figure, for R = 20 ohms the current I is 2 A. When R is 10 ohms the current I would be

A. 1 A B. 2 A 607. value of R is

C. 2.5 A D. 3 A In the figure, the

609. A network contains only independent current sources and resistors. If the values of all the resistors are doubled, the values of the node voltage A. will become half B. will remain unchanged C. will become double D. cannot be determined unless the circuit configuration and the values of the resistors are known 610. A network N is a dual of network N if A. both of them have same mesh equations B. both of them have same node equations C. mesh equations of one are the node equations of the other D. KCL and KVL equations are the same 611. A certain network consists of two ideal voltage sources and a large number of ideal resistors. The power consumed in one of the resistor is 4 W when either of the two sources is active and the other is replaced by a short circuit. The power consumed by the same resistor when both the sources are simultaneously active would be A. zero or 16 W C. zero or 8 W B. 4W or 8 W D. 8 W or 16 W 612. All the resistances in the circuit are R ohms each. The switch is initially open. What happens to the lamp intensity when the switch is closed?



608. An ideal constant voltage source is connected in series with an ideal constant current source. Considered together, the combination will be a A. constant voltage source B. constant current source C. constant voltage source and constant current D. source or a constant power source

A. B. C. D.

increases decreases remain constant depends on the value of R

613. If R1 = R2 = R4 = R and R3 = 1.1R in the bridge circuit shown in figure, then the reading in the ideal voltmeter connected across a and b is A. – 100 V, 30 Ω B. - 2 V, 30 Ω

C. 10/3 V, 30 Ω D. none of these

618. Identify correct statement with respect to fig. (a) and (b).

A. 0.238 V B. 0.138 V

C. –0.238 V D. 1 V

614. A network has b branches and n nodes. For this mesh analysis will be simpler than node analysis if n is greater than A. b C. b/2 +1 B. b + 1 D. b/2 615. following

A. B. C. D.

I1/I2 P1/P2 P1 in Watts P2 in Watts

ABCD A. 3 5 4 1 B. 2 3 4 1

Match

the

A. power supplied by both the sources is same B. current flowing through 5 Ω resistors are same C. current flowing through 1 Ω resistors are same D. all are correct 619. Practical current source internal resistance should be A. Less than RL C. equal to RL B. greater than RL D. none of these

1. 2. 3. 4. 5.

600 0.3 2 500 1.2 ABCD C. 3 5 1 4 D. 1 3 1 4

616. Find current source equivalent.

620. The circuit of the following circuit is

equivalent

single A. B. C. D.

V in series with 3R 3V in series with 3R V in series with R/3 3V in series with R/3

621. Obtain potential of node B with respect to G in the network shown in figure. A. 1 A, 2.73 Ω B. 2.73 A, 1 Ω

C. 5A, 30/11 Ω D. none of these

617. The value of equivalent voltage and resistance across a and b.

A. zero B. 80 W

A. 64/63 V B. 1 V 622. dissipated in resistor 1 Ω.

626. Find the total power absorbed by all resistors in the circuit shown.

C. 63/64 V D. 32/63 V Find

C. 125 W D. 405 W

power A. 15 W B. 20 W

C. 25 W D. 30 W

627. What will be the power consumed by the voltage source, current source and resistance respectively A. 0 B. 6 W 623. delivered at t = 0.8 s.

C. 9 W D. none of these Find

power

A.

1 W, 1 W, 2 W

C. 1 W, 0 W, 1

W A. 51 W B. 34.68 W

C. – 34.68 W D. none of these

624. The total power consumed in the circuit shown in the figure is

B. 0 W, -1 W, 1 W W

628. Power absorbed by 6 Ω resistor is 24 W. Determine Io

A. 4 A B. -4 A A. 10 W B. 12 W

C. 16 W D. 20 W

625. In the circuit shown in the given figure, power dissipation in the 5 Ω resistor is

D. 0 W, 0 W, 0

629. current source shown

C. 2 A D. none of these The

dependent

A. Delivers 80 W B. absorbs 80 W

C. delivers 40 W D. absorbs 40 W

630. Find absorbed by dependent source.

634. A delta– connected network with its WYE-equivalent is shown. The resistances R1 R2 & R3 are

power

A.

1.5 Ω, 3 Ω, 9 Ω

C. 9 Ω, 3 Ω, 1.5

B. 3 Ω, 6 Ω, 1.5 Ω

D. 3 Ω, 1.5 Ω,

Ω A. –3 W B. 3 W

C. 0 W D. none of these

631. What is power supplied by 2 A current source.

the

9Ω 635. When all resistances in delta connection are having equal value of R. What is the equivalent resistance in star connection? A. RY = RΔ C. RY = RΔ/3 B. RΔ = RY/3 D. none of these 636. The effective resistance between the terminals A and B in the circuit shown in the figure is (all resistors are equal to R)

A. –70 W B. 70 W

C. 50 W D. none of these

632. Each branch resistance is 1 ohm. Find equivalent resistance in each path out of 3 paths.

A. R B. R - 1

C. R/2 D. (6/11) R

637. What is the equivalent resistance between AB when each branch resistance is 2 ohms? A. 15/6 ohms B. 5/6 ohms 633.

C. 6/5 ohms D. none of these If each branch of

a delta circuit has impedance

√3

Z, then

each branch of the equivalent Wye circuit has impedance A.

Z/

B. 3Z

√3

C. 3

√3

D. Z/3

Z

A.

3.23 ohm

C. difficult

to

find B. 2 ohm

D. none of these

638. Superposition theorem is not applicable in the network when it is A. Linear C. Time varying B. non-linear D. Time invarying

639. The superposition theorem is valid for A. all linear networks B. linear and symmetrical networks only C. only linear networks having no dependent sources D. linear as well as nonlinear networks

Thevenin’s theorem is applicable to two terminal linear active networks 4. Norton’s theorem is applicable to two terminal linear active networks Which of these statements are correct? A. 1, 2 and 3 C. 1, 2 and 4 B. 1, 2, 3 and 4 D. 3 and 4

640. Substitution theorem is not used in the analysis of networks in which they contain elements as A. Linear C. Time varying B. non-linear D. none of these

645. Match List–I with List-II and select the correct answer using the codes given below the lists: List I List II Network Theorems Most distinguished property of network A. Reciprocity 1. Impedance Matching B. Tellegen’s 2. Bilateral C. Superposition 3.

641. Thevenin’s theorem is not applicable when 1. Load is coupled with the network 2. Linear 3. Time invariant 4. none of these 5. Non linear 6. Time varying A. 1, 5, 6 C. 1, 5 B. 5, 6 D. 1, 3, 5, 6 642. Tellegen’s theorem is applicable when A. Nature of elements is irrelevant B. Elements are linear time varying C. KVL and KCL is not satisfied D. none of these 643. Reciprocity theorem is applicable when network is 1. Linear 2. Time invariant 3. Passive 4. Independent source 5. Dependent source 6. Mutual inductors Identify the correct combination A. 1, 2, 6 C. 1, 2, 4 B. 1, 2, 3, 6 D. 1, 2, 3 644. Consider the following statements: 1. Tellegen’s theorem is applicable to any lumped networks 2. The reciprocity theorem is applicable to linear bilateral networks

3.

b

∑ V jk (t1 ) I jk (t2 )=0 k=0

D. Maximum power Transfer CODES: ABCD A. 1 2 3 4 B. 1 2 3 5

4.

Linear

5.

Non linear CODES: ABCD C. 2 3 4 1 D. 2 3 5 1

646. In a linear circuit the super position principle can be applied to calculate the A. Voltage and power B. voltage and current C. current and power D. voltage, current and power 647. In applying Thevenin’s theorem, to find the Thevenin impedance, some sources (call them set S 1) have to be replaced by their internal impedances, while others (call them set S 2) should be left undisturbed. A. S1 consists of independent sources while S2 includes all independent sources B. S1 consists of dependent sources while S 2 includes all independent sources C. S2 is a null set D. S1 is a null set

648. In the network shown, which one of the following theorems can be conveniently used to calculate the power consumed by the 10 ohm resistor. A. 4 V, 2 Ω B. 4 V, 4 Ω

A. B. C. D.

Thevenin’s theorem Maximum power transfer theorem Millman’s theorem Superposition theorem

649. Find the Thevenin equivalent resistance of the circuit to the left of the terminals marked a and b in the figure.

C. 8 V, 2 Ω D. 8 V, 4 Ω

652. A battery charger can drive a current of 5A into a 1 ohm resistance connected at its output terminals. If it is able to charge an ideal 2V battery at 7A rate, then its Thevenin’s equivalent circuit will be A. 7.5V in series with 0.5 ohm B. 12.5 V in series with 1.5 ohms C. 7.5V in parallel with 0.5 ohm D. 12.5V in parallel with 0.5 ohm 653. Find Va for which maximum power is transferred to the load.

A. 0.2 Ω B. 0.4 Ω

C. 2Ω D. none of these

650. A dc current source is connected as shown in below figure. The Thevenin’s equivalent of the network at terminals a – b will be

A. 4 V voltage source parallel with 2 ohms resistor B. 4 V voltage source C. 2 V voltage source parallel with 2 ohms resistor D. none of these 651. In the network shown in the given figure current i= 0 when E = 4 V, I = 2 A and I = 1 A when E = 8 V, I = 2A. The Thevenin voltage and the resistance looking into the terminals AB are

A. 7.5 V B. 20 V

C. 10 V D. none of these

654. If the networks shown in fig. I and II are equivalent at terminals A-B, then the values of V (in volts) and Z (in ohms), will be

V A. 100 B. 60

Z 12 12

V C. 100 D. 60

Z 30 30

655. In the circuit shown, the power dissipated in 30 ohm resistor will be maximum if the value of R is


C. 9 ohms D. zero

656. In the circuit shown, the power consumed in the resistance R is measured when one source is acting at a time. These values are 18 W, 50 W and 98 W. When all the sources are acting simultaneously, the possible maximum and minimum values of power in R will be

A. 2.75 Ω B. 7.5 Ω

C. 25 Ω D. 27 Ω

659. For the circuit shown, identify the correct statement.

A. A. 98W and 18 W 2W B. D. 166 W and 2 W

C. 450 W and 166 W and 18 W

657. The value of Rx so that power dissipated in it is maximum

A. 33.4 kohms B. 17.6 kohms

C. 10 kohms D. 5 kohms

658. In the circuit shown in the given figure RL will absorb maximum power when its value is

Efficiency of power transmission is maximum when RS = RL B. efficiency of power transmission is maximum when RS < RL C. efficiency of power transmission is maximum when RS > RL D. none of these 660. The V-I characteristics as seen from the terminal-pair (A, B) of the network of figure (a) is shown in figure (b). If a variable resistance R L is connected across the terminal – pair (A, B) the maximum power that can be supplied to RL would be

A. B. C. D.

80 W 40 W 20 W Indeterminate unless the actual network is given

661. In the lattice network, find the value of R for the maximum power transfer to the load.

A. 5 Ω B. 6.5 Ω

662. In the network of the given figure, the maximum power is delivered to RL if its value is

A. 16 ohms B. 40/3 ohms 663. in the given figure.

A. 1.5 A B. 2.0 A

A. 1 W B. 10 W

C. 8 Ω D. 9 Ω

C. 0.25 W D. 0.5 W

666. For the circuit shown, Thevenin’s voltage and Thevenin’s equivalent resistance at terminals a and b is

A. B. C. D.


5 V and 2 ohms 7.5 V and 2.5 ohms 4 V and 2 ohms 3 V and 2.5 ohms

Find the current I 667. Find the value of R and r. Thevenin’s equivalent circuit is given by circuit as shown

C. 1.2 A D. –4/5 A

A. B. C. D.

664. In the circuit of the given figure, the maximum power will be delivered to RL and RL equals

R = r = 20 ohms R = r = 5 ohms R = 10 ohms; r = 5 ohms R = r = 10 ohms

668. Thevenin’s equivalent of the circuit shown in the figure: Vth, Zth values are

A. 6 Ω B. 2 Ω

C. 4/3 Ω D. 1 Ω

665. The maximum power that can be transferred to the load resister RL from the voltage source in the figure is

A. 20 V, 9 ohms B. 40 V, 19/3 ohms ohms F.

C. 40 V, 9 ohms D. 40 V, 8

ELECTRICAL TRANSIENTS

669. EE Board Exam April 1979, October 1982 In an RL circuit, Kirchhoff’s law gives the following relation: E = Ldi/dt + Ri where: E = supply voltage (200 volts) R = resistance (20 ohms) L = inductance (1 Henry) t = time in seconds i = current in amperes If i = 0 when t = 0, find i when t = 0.02 second. A. 3.3 A C. 3.2 A B. 3.1 A D. 3.0 A 670. EE Board Exam October 1980 In an RL circuit, Kirchhoff’s law gives the following relation: E = Ldi/dt + Ri where: E = supply voltage (200 volts) R = resistance (20 ohms) L = inductance (1 Henry) t = time in seconds i = current in amperes If i = 0 when t = 0, find i after a long time. A. 10 A C. 0 B. 11.2 A D. infinite 671. EE Board Exam October 1990 A 6 H coil whose resistance is 12 ohms is connected in series with a 24 ohms resistor and to a 144 V battery and a switch. The switch is closed at t = 0. Determine the time constant and the steady state current of the circuit. A. 0.36 sec, 12 A C. 0.66 sec, 3 A B. 0.45 sec, 4 A D. 0.50 sec, 6 A 672. EE Board Exam April 1990 A time of 10 milliseconds is required for the current on a series RL dc circuit to reach 90% of its final steady state value. Assume at t = 0, i(0) = 0. What is the time constant in seconds for the circuit? A. 4.25 ms C. 3.39 ms B. 3.86 ms D. 4.34 ms 673. EE Board Exam April 1995 The shunt winding of a machine has a resistance of 80 ohms and an inductance of 4 H is suddenly switched on to a 220 V supply. Find the time taken for the current to rise to half its steady state value.

A. 0.0512 sec B. 0.0346 sec

C. 0.0251 sec D. 0.0172 sec

674. EE Board Exam October 1990 A 6 H coil whose resistance is 12 ohms is connected in series with a 24 ohms resistor and to a 144 V battery and a switch. The switch is closed at t = 0. Determine the current at t = 0.1 second. A. 1.538 A C. 1.805 A B. 1.750 A D. 1.624 A 675. EE Board Exam October 1992 An uncharged capacitor in series with a 120 volt voltmeter of 10,000 ohms resistance is suddenly connected to a 100 V battery. One second later, the voltmeter reads 60 volt. Determine the capacitance of the capacitor. A. 187.54 μF C. 195.76 μF B. 190.62 μF D. 192.23 μF 676. REE Board Exam April 1999 A 20 ohm resistance R and a 0.001 farad capacitance C are in series. A direct current voltage E of 100 volts is applied across the series circuit at t = 0 and the initial current i(0) = 5 A. Determine the resulting current i(t) at t = 0.01 second. A. 3.34 A C. 2.78 A B. 3.67 A D. 3.03 A 677. EE Board Exam October 1991 A series RC circuit consist of R = 2 MΩ and an uncharged capacitor C = 5 μF. The circuit is connected across a 100 V DC source at t = 0. Determine the voltage across the resistor 5 seconds later. A. 63.31 V C. 66.24 V B. 60.65 V D. 69.22 A 678. EE Board Exam October 1991 An uncharged capacitor in series with a 120 volt voltmeter of 10,000 ohms resistance is suddenly connected to a 100 V battery. One second later, the voltmeter reads 60 volt. Determine the rate at which the voltage across the capacitor is charging. A. 51 e-0.55t C. 55 e-0.55t -0.51t B. 51 e D. 55 e-0.51t 679.

EE Board Exam October 1981

In a circuit consisting of a series resistance and capacitance and connected to a DC source, R = 20 ohms, C = 250 microfarad and E = 100 volts, find i after a long time. A. 1 A C. infinity B. 0 A D. 5 A 680. EE Board Exam April 1993 A 100 μF capacitor initially charged to 24 V is discharge across a series combination of a 1 kΩ resistor and a 200 μF capacitor. Find the current after 1 sec. A. 7.34 nA C. 8.43 nA B. 7.24 nA D. 8.84 nA 681. EE Board Exam October 1991 A series RC circuit consist of R = 2 MΩ and an uncharged capacitor C = 5 μF. The circuit is connected across a 100 V DC source at t = 0. What is the initial rate of change of voltage across the resistor? A. -10 V/s C. -12.4 V/s B. 10 V/s D. none of these 682. REE Board Exam March 1998 A 10 ohm resistance R and a 1 Henry inductance L are connected in series. An AC voltage e(t) = 100 sin 377t is applied across the connection. Solve for the particular solution (without the complementary solution) and determine the amplitude of the resulting sinusoidal current i(t). A. 0.321 A C. 0.241 A B. 0.292 A D. 0.265 A 683. EE Board Exam April 1991 A certain electric welder has a basic circuit equivalent to a series RL with R = 0.1 Ω and L = 1 mH. It is connected to an AC source “e” through a switch “s” operated by an automatic timer, which closes the circuit at any desired point on the 60 cycle, sinusoidal wave ”e”. Calculate the magnitude of the transient current resulting when “s” closes as “e” is passing through its peak value of 100 volts. A. 256.41 A C. 80.54 A B. 65.74 A D. 76.32 A 684. REE Board Exam October 1999 A series RL circuit is connected to an AC source of 100 sin 377t. Where L = 0.1 Henry,

R = 10 ohms and i(0) = 0. Determine the current at t = 0.01 second. A. 2.784 A C. 2.531 A B. 2.301 A D. 3.062 A 685. REE Board Exam April 1999 A series circuit has R = 10 ohms. L = 0.1 Henry and C = 0.0001 Farad. An AC voltage e = 100 sin 377t is applied across the series circuit. Solve for the particular solution (without the complementary solution) and determine the amplitude of the resulting sinusoidal current i(t). A. 5.51 A C. 6.67 A B. 6.06 A D. 7.34 A 686. REE Board Exam October 1999 A 10 ohm resistance R and a 0.001 Farad capacitance C are in series. An AC voltage e(t) = 100 sin 377t is applied across the series circuit. Solve for the particular solution (without the complementary solution) and determine the amplitude of the resulting sinusoidal current i(t). A. 9.67 A C. 8.79 A B. 10.63 A D. 11.70 A 687. REE Board Exam October 1999 If R = 50 ohms, C = 0.0001 Farad, E = 100 volts and i(0) = 2 amperes, determine the Laplace transform expression for I(s). A. I(s) = 2/(s + 200) C. I(s) = 2/(s + 50) B. I(s) = 2/[s(s + 2)] D. I(s) = 2/(s + 2) 688. REE March 1998 A generator has a field winding with an inductance L = 10 Henry and a resistance Rf = 0.1 ohm. To break the initial field current of 1000 amperes, the field breaker inserts a field discharge resistance Rd across the field terminals before the main contacts open. As a result, the field current decays to zero according to the differential equation.

L

di +iR=0 dt

Where: R = Rf + Rd

preventing a sudden decrease of i to zero, and a resulting high inductive voltage due to L. Solve the differential equation and

determine the value of Rd that would limit the initial voltage across it to 1,000 volts A. 0.90 ohm C. 0.85 ohm B. 0.80 ohm D. 0.95 ohm 689. EE Board Exam April 1995 The growth of current in an inductive circuit follows A. Linear law C. Ohm’s law B. Exponential law D. Hyperbolic law 690. EE Board Exam April 1994 The time constant of an RL series circuit is A. R + L C. L/R B. R/L D. RL 691. EE Board Exam April 1998, April 1995 If a dc voltage is applied to an initially uncharged series RC circuit, the initial value of the current is A. zero C. infinite B. V/R D. CV 692. ECE Board Exam April 1999 What is the voltage drop across the resistor in an RC charging circuit when the charge on the capacitor is equal to the battery voltage? A. 0.10 volt C. zero B. 1.0 volt D. 10 volts 693. ECE Board Exam April 2000 What is the RC time constant of a series RC circuit that contains a 12 MΩ resistor and a 12 F capacitor? A. 144 seconds B. 1.44 seconds

C. 14.4 seconds D. 1440 seconds

694. ECE Board Exam April 2000 What is the time constant of a 500 mH coil and a 3,300 ohm resistor in series? A. 0.0015 sec C. 1650 secs B. 6.6 secs D. 0.00015 sec 695. ECE Board Exam November 2000 In RL circuit, the time constant is the time required for the induced current to reach what percentage of its full value? A. 100% C. 37% B. 63% D. 0%

696. EE Board Exam April 1990, October 1990 A 6 H coil whose resistance is 12 ohms is connected in series with a 24 ohms resistor and to a 144 V battery and a switch. The switch is closed at t = 0. Determine the time constant of the circuit and the steady-state current. A. 0.5 sec; 6 A C. 0.1667 sec; 4A B. 0.25 sec; 12 A D. 0.131 sec; 6 A 697. EE Board Exam October 1991 A series RC circuit consist of R = 2 MΩ and an uncharged capacitor C = 5 μF. The circuit is connected across a 100 V DC source at t = 0. Determine the voltage across the resistor at the instant the switch is closed and 5 seconds after the switched has been closed. A. 100 V, 60.65 V C. 100 V, 0 V B. 0 V, 60.65 V D. 0 V, 100 V 698. The rate of rise of current through an inductive coil is maximum A. after 1 time constant B. at the start of current flow C. near the final maximum value of current D. at 63.2% of its maximum steady state value 699. Energy stored by a coil is doubled when its current is increased by ____. A. 100% C. 50% B. 41.4% D. 25% 700. The initial current in an RL series circuit when a dc source is suddenly applied A. unity C. infinite B. V/R D. zero 701. At steady state in an RL circuit, the inductance will act as A. open circuit C. transient circuit B. short circuit D. coupled circuit

702. The rise of the current in an RL series circuit is what? A. linear C. exponential B. sinusoidal D. symmetrical 703. current is undamped if A. R = 0 B. [R/2L]2 > [1/(LC)] C. [R/2L]2 = [1/(LC)] D. [R/2L]2 < [1/(LC)]

The

704. current is oscillatory if A. R = 0 B. [R/2L]2 > [1/(LC)] C. [R/2L]2 = [1/(LC)] D. [R/2L]2 < [1/(LC)]

The

transient

transient

705. The capacitor in a series RC circuit at steady state is A. open circuit C. transient circuit B. short circuit D. coupled circuit 706. What is the time constant in an RC series circuit? A. C/R C. RC B. R/C D. C

710. There are no transients in pure resistive circuits because they A. offer high resistance B. obey Ohm’s law C. have no stored energy D. are linear circuits 711. Transient currents in electrical circuit are associated with A. inductors C. resistors B. capacitors D. both A and B 712. The transients which are produced due to sudden but energetic changes from one steady state of a circuit to another are called ____ transients. A. initiation C. relaxation B. transition D. subsidence 713. In a R-L circuit connected to an alternating sinusoidal voltage, size of transient current primarily depends on A. the instant in the voltage cycle at which circuit is closed B. the peak value of steady-state current C. the circuit impedance D. the voltage frequency

707. A circuit of resistance and inductance in series has an applied voltage of 200 volts across it. What is the voltage drop across the inductance at the instance of switching? A. 200 V C. 20 V B. 0 V D. 2,000 V

714. Double-energy transients are produced in circuits consisting of A. two or more resistors B. resistance and inductance C. resistance and capacitance D. resistance, inductance and capacitance

708. The current series RC circuit at steady state is A. zero C. constant B. infinite D. V/R

715. The transient current in a loss-free L-C circuit when excited from an ac source is a/an ____ sine wave. A. over damped B. undamped C. under damped D. critically damped

in

709. Transient disturbance is produced in a circuit whenever A. it is suddenly connected or disconnected from the supply B. it is shorted C. its applied voltage is changed suddenly D. all of the above

716. Transient currents in an R-L-C circuit is oscillatory when A.

R=0

C.

R< √ L/C

B.

R> √ L/C

D.

R= √ L/C 717. A coil has a time constant of 1 second and an inductance of 8 H. If the coil is connected to a 100 V dc source, determine the rate of rise of current at the instant of switching. A. 8 amp/sec C. 0.25 amp/sec B. 12.5 amp/sec D. 0.04 amp/sec 718. A 20 ohm resistor, a 0.01 H inductor and a 100 uF capacitor are connected in series to a 200 V DC supply. The capacitor is initially uncharged. Find the maximum instantaneous current. A. 8.44 A C. 6.44 A B. 7.44 A D. 5.44 A . 719. A 10,000 ohms voltmeter connected in series with 80 F capacitor is suddenly connected to a 100 V dc source at t = 0. At what time does the voltmeter read 40 volts? A. 0.654 sec C. 0.733 sec B. 0.51 sec D. 0.1 sec 720. A series RLC circuit with inductance of 100 Henry has a transient resonant frequency of 5 cps. Solve the capacitance of the circuit if the effect of R on the frequency is negligible. A. 10.1 F C. 400 F B. 0.104 F

D. 4 F

721. A 60 μF capacitor is connected in series with a 400 ohm resistor. If the capacitor is initially uncharged, determine the resistor and capacitor voltages when t = 1.5 times the time constant for a suddenly applied source emf of 120 volts. A. 26.78 V, 93.22 V B. 120 V, 0 V C. 93.22 V, 26.78 V D. 0 V, 120 V 722. A series RL network, with R = 2 ohms and L = 0.5 H, has

an applied voltage v(t). Find the time constant for the circuit current. A. 4 sec C. 2 sec B. 0.5 sec D. 0.25 sec 723. A coil having a resistance of 10 ohms and an inductance of 4 H is switched across a 20-V dc source. Calculate the time taken by the current to reach 50% of its final steady state value. A. 151.8 V C. 88.2 V B. 189.4 V D. 101.2 V 724. A constant voltage is applied to a series RL circuit at t = 0 by closing the switch. The voltage across L is 25 volts at t = 0 and drops to 5 volts at t = 0.025 second. If L = 2 H, what must be the value of R in ohms? A. 188.30 C. 128.80 B. 1288 D. 182.80 725. A circuit whose resistance is 20 ohms and inductance of 10 H has a steady state voltage of 100 volts suddenly applied to it. For the instant of 0.50 second after the voltage is applied, determine the total power input to the circuit. A. 200 watts B. 116 watts

C. 316 watts D. 500 watts

726. A circuit of resistance R ohms and inductance L Henry has a direct voltage of 230 volts applied to it. 0.30 second after switching on, the current was found to be 5 ampere. After the current had reached its final value, the circuit was suddenly short-circuited. The current was again found to be 5 ampere at 0.30 second after short-circuiting the coil. Find the value of R and L. A. 230 Ω, 10 H C. 10 ohms. 23 H B. 23 Ω, 10 H D. 10 Ω, 32 H 727. The field winding of a separately-excited DC generator has an inductance of 60 H and a resistance of 30 ohms. The discharge resistance of 50 ohms is permanently connected in parallel with winding which is excited from a 200 volt supply. Find the value of the decay current

0.60 sec after the supply has been switched off. A. 4.94 A C. 1.12 A B. 3.67 A D. 3 A 728. A 5 microfarad capacitor is discharged suddenly through a coil having an inductance of 2 H and a resistance of 200 ohms. The capacitor is initially charge to a voltage of 10 volts. Find the additional resistance required just to be prevent oscillation. A. 1625 ohms C. 1265 ohms B. 1065 ohms D. 1025 ohms 729. The rate of rise of current through an inductive coil is maximum A. after 1 time constant B. at the start of current flow C. near the final maximum value of current D. at 63.2% of its maximum steady state value 730. A coil of 15 H inductance and 10 ohms resistance is suddenly connected to a 20 volts DC source by closing the switch. The value of current 2 seconds after the switch is closed is A. 1.74 A C. 1.17 A B. 1.47 A D. 1.71 A 731. A DC voltage of 80 volts is applied to a circuit containing a resistance of 80 ohms in series with an inductance of 20 Henry. Calculate the growth of current at the instant of completing the circuit. A. 4 A/s C. ½ A/s B. 2 A/s D. ¼ A/s 732. A 200 volt DC supply is suddenly switched to a relay coil which has a time constant of 3 ms. If the current in the coil reaches 0.20 ampere after 3 ms determine the steady state value of the current. A. 0.361 A C. 0.316 A B. 0.163 A D. 0.631 A 733. A relay has a resistance of 300 ohms and is switched to a 100 V DC supply. If the current reaches

63.2% of its final value at 0.02 determine the inductance of the circuit. A. 5 H C. 4 H B. 6 H D. 13 H

sec,

734. Energy stored by a coil is doubled when its current is increased by ____ percent. A. 100 C. 50 B. 141.4 D. 25 735. A 60 volt potential difference is suddenly applied to a coil of inductive 60 mH and resistance 180 ohms. At what rate is it rising after 0.005 sec? A. 322 A/sec C. 22.3 A/sec B. 223 A/sec D. 32.2 A/sec 736. A voltage rise linearly form zero to 100 volts in 1 second, falls instantaneously to zero at t = 1 second and remains zero thereafter. This voltage is applied to an RL series circuit in which R = 5 ohms and L = 100 mH. What is the current when t = 0.50 second? A. 6.90 A C. 9.60 A B. 96 A D. 69 A 737. A capacitance of 10 microfarad is connected in series with a resistance of 8,000 ohms. If the combination is suddenly connected to a 100 V DC supply. Find the initial rate of rise in potential across the capacitor. A. 12500 V/s C. 1250 V/s B. 125 V/s D. 12.50 V/s 738. A 25 microfarad capacitor is connected in series with a 0.50 M-ohm resistor and a 120 volt storage battery. What is the potential difference in the capacitor 6 sec after the circuit is closed? A. 64 volts C. 4.60 volts B. 46 volts D. 6.40 volts 739. A capacitor of 2 microfarad with an initial charge q0 is connected across the terminals of a 10 ohm resistor and the switch is closed at t = 0. Find q0 (micro-coulomb) if the transient power in

the

resistor

is

known

to

be

B. 4.61 mA

D. 5.05 mA

−5

−10 t

pR =360 e A. 1200 B. 120

C. 102 D. 2100

740. The transient current in a loss-free L-C circuit when excited from an ac source is ____ a/an sine wave . A. overdamped B. undamped C. underdamped D. critically damped 741. A series RLC circuit with R = 5 ohms, L = 0.10 H, C = 500 microfarad has a constant voltage V = 10 volts applied at t = 0. Find the resulting transient current. A. 0.707e-50t sin 139t B. 0.272e-25t sin 278t C. 0.720e-25t sin 139t D. none of these 742. A circuit consisting of 20 ohms resistor, 20 mH inductor and a 100 microfarad capacitor in series is connected to a 200 V DC supply. The capacitor is initially uncharged. Find the maximum instantaneous current. A. 6.45 A C. 8.45 A B. 7.45 A D. 9.45 A 743. A time of 10 ms is required for the current in an RL circuit to reach 90% of its final value. If R is 10 ohms, find the value of C to be inserted in series with the RL circuit so that the frequency of oscillation of the resulting current is 1000 cycles per second. A. 5.38 x 10-8 Farad B. 5.83 x 10-7 Farad C. 5.83 x 10-6 Farad D. 5.83 x 10-5 Farad 744. A series RLC circuit with R = 1 kΩ, L = 1 H and C = 6.25 μF is suddenly connected across a 24 V dc source. At t = 0, i= 0 and q = 0. Determine the current after 0.01 sec. A. 3.45 mA C. 5.40 mA

745. A series RLC circuit has R = 200 Ω, L = 0.1 H and a capacitor C = 10 μF. If a 100 V dc source is connected across the terminals of the series circuit at t = 0, determine the current after 1 millisecond. Assume zero initial conditions. A. 0.353 A C. 0.253 A B. 0.229 A D. 0.368 A 746. Double energy transient are produced in circuits consisting of A. two or more resistors B. resistance and inductance C. resistance and capacitance D. resistance, inductance and capacitance 747. A DC voltage source is connected across a series RLC circuit, under steady state conditions, the applied DC voltage drops entirely across the A. R only B. L only C. C only D. R & L combinations 748. Consider a DC voltage source connected to a series RC circuit. When the steady state reaches, the ratio of energy stored in the capacitor to the total energy supplied by the voltage source is equal to A. 0.362 C. 0.632 B. 0.500 D. 1.00 749. An inductor at t = 0 with initial current I0 acts as A. short C. current source B. open D. voltage source 750. An inductor L carries steady state current I0, suddenly at time t = 0 the inductor is removed from circuit and connected to a resistor R. The current through the inductor at time t is equal

A. I0e-Rt/L B. I0 (1-e-Rt/L)

C. I0e+Rt/L D. I0 (1-e+Rt/L)

751. Transient current in a circuit results from A. voltage applied to the circuit B. impedance of the circuit C. changes in the stored energy in inductors and capacitors D. resistance of the circuit 752. A two terminal black box contains a single element which can be R, L, C or M. As soon as the box is connected to a dc voltage source, a finite non-zero current is observed to flow through the element. The element is a/an A. resistance B. inductance C. capacitance D. Mutual inductance 753. In a circuit the voltage across an element is v(t) = 10 (t 0.01)e-100t V. The circuit is A. un-damped B. under damped C. critically damped D. Over damped 754. A unit step voltage is applied at t = 0 to a series RL circuit with zero initial conditions A. It is possible for the current to be oscillatory B. The voltage across the resistor at t = 0+ is zero C. The energy stored in the inductor in the steady state is zero D. The resistor current eventually falls to zero 755. A 1 µF capacitor charged through a 2 kΩ resistor by a 10 V dc source. The initial growth of capacitor voltage will be at the rate A. 3.16 V/ms C. 6.32 V/ms B. 5.0 V/ms D. 10.0 V/ ms 756. A series R-C circuit has a capacitor with an initial voltage

of 11 V. A 15 V dc source is now connected across the R-C circuit. The initial rate of change of capacitor voltage can be A. 15 Χ 0.368 / RC C. 11/RC B. 15Χ 0.632 / RC D. 4/RC 757.

What is vc (o+)?

A. 0 B. V

C. can’t find D. none of these

758. The switch K opened at t = 0 after the network has attained a steady state with the switch closed. Find vs (0+) across the switch.

A. VR1/R2 B. V

C. V + VR1/R2 D. 0

759. The switch SPST is closed at t = 0, find d/dt i1 (0+).

A. 0 B. 40


760. SPST is closed at t = 0.What is the time constant of the circuit?

A.

26/7

C. 7/13

B. 7/26

D. none of these

761. Given VC1 (0-) = 10 V, VC2 (0-) = 5 V find VC2 (∞) = ?

A. 7.5 V B. 0

C. 20/3 V D. none of these

762. Given initial charge in C0 = 500 µC. In the steady state find charge in 1 µf capacitor?

A. 2 V B. -2 V


766. An impulse current 2 δ(t) A, with t in second, is made to flow through an initially relaxed 3 F capacitor. The capacitor voltage at T = 0+ is A. 6V C. 2/3 V B. 2V D. zero 767. The circuit of the given figure is initially relaxed. At t = 0+, ____.

A. 50 µC B. 100 µC

C. 250 µC D. none of these

763. Switch opened at t = 0, find IL (0+).

K

is A. v =0 V B. i = 0 A

C. v = 100 V D. i = ∞

768. The time constant of the circuit shown in figure is A. 5 A B. 0

C. 2A D. none of these

764. Given L1 = 1 H, R = 10 Ω , L2 = 2 H , iL1 (0-) = 2A. Find iL2 (∞). A. C(R1 +R2 ) B. CR1R2/(R1+R2 ) A. 2/3 A B. 0

C. 4/3 A D. 1A

C. CR1 D. CR2

769. If i1(t) is 5 A at t = 0, find i1(t) for all t when is(t) = 10 e-2t.

765. What is VL (0 +), when switch K is closed at t = 0.

A.

e-2t

C. 30e-2t

B. 20e-2t 1.67

D. 6.67e-2t

-

770. The switch in the circuit of the figure has been closed for a long time. It is opened at t = 0.

A. B. C. D.

v(0+) = 1 V, i (0+) = 0 A v(0+) = 0 V, i(0+) = 0 A v(0+) = 0 V, i (0+) =1 A v (0+) = 1 V, i(0+) = 1 A

771. In the circuit shown, the switch is moved from position A to B at time t = 0. The current i through the inductor satisfies the following conditions 1. i(0) = -8A 2. di/dt (t = 0) = 3 A/s 3. i(∞) = -4A The value of R is

773. In the network shown, the switch is opened at t = 0. Prior to that, network was in the steady- state, Vs (t) at t =0 is

A. 0 B. 5V

C. 10V D. 15V

774. For the circuit shown different time constants are given. What are the charging and discharging times respectively? 1. 0.5 x 10-3 S 2. 2 x 10-3 S 3. 0.25 x 10-3 S 4. 10-3 S

A. 1, 2 B. 2, 3

C. 1, 3 D. 2, 4

775.

A. 0.5 ohm B. 2.0 ohm

C. 4.0 ohm D. 12 ohm

772. In the circuit shown below, the switch is closed at t = 0. The current through the capacitor will decrease exponentially with a time constant

A. 0.5 s B. 1 s

C. 2s D. 10s

A. B.

C. D.

776. A. B.

C. D.

777. A. B.

C. D.

778. A. B.

C. D.

779. A. B.

780. If Vs = 40t V for t > 0 and iL (0) = 5A, what is the value of i(t) at t = 2sec? A. 24A B. 34A 781. A. B. 782. A. B. 783.

A. B.

C. D.

C. 29A D. 39A

784. following units: 1. sec-1 2. rad2-sec-2 3. second 4. Ohm

C. D.

Consider

The units of R/L, 1/LC, CR and respectively ____. A. 1, 2, 4 and 3 B. 3, 2, 1 and 4

C. D. 4 C. D.

√ L/C

the

are

C. 2, 4, 1 and 3 D. 1, 2, 3 and

Question Bank in DC Circuits

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