Essential University Physics, 3e (Wolfson) 3e (Wolfson) Chapter 25 Electric Circuits
2 5. 1 Co nc e pt ua lQue s t i o ns 1) As more resistors resistors are added in parallel across a constant voltage source, the power supplied by the source A) increases. B) decreases. C) does not change. Answer: A Var: 1
2) he !igure shows three identical lightbulbs connected to a battery having a constant voltage across its terminals. "hat happens to the brightness o! lightbulb 1 when the switch S is is closed#
A) he brightness will increase momentarily then return to its previous level. B) he brightness increases permanently. C) he brightness will decrease momentarily then return to its previous level. $) he brightness remains the same as be!ore the switch is closed. %) he brightness decreases permanently. Answer: B Var: 1
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+) *n the circuit shown in the !igure, all the lightbulbs are identical. "hich o! the !ollowing is the correct raning o! the brightness o! the bulbs#
A) B A) B and and C have have e-ual brightness, and A and A is is the dimmest. B) A B) A and and B B have have e-ual brightness, and C is is the dimmest. C) A C) A is is brightest, C is is dimmest, and B and B is is in between. $) A $) A is is the brightest, and B and B and and C have have e-ual brightness but less than A than A.. %) All three bulbs have the same brightness. Answer: $ Var: 1
) *n the circuit shown in the !igure, !our identical resistors labeled A labeled A to to D D are are connected to a battery as shown. S 1 and S 2 are switches. "hich o! the !ollowing actions would result in the /0%A% /0%A% amount o! current through resistor A resistor A##
A) closing both switches B) closing S 1 only C) closing S 2 only $) leaving both switches open as shown. Answer: A Var: 1
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) A resistor is made out o! a long wire having a length L. %ach end o! the wire is attached to a terminal o! a battery providing a constant voltage V '. A current I !lows through the wire. *! the wire were cut in hal!, maing two wires o! length L32, and both wires were attached to the battery 4the end o! both wires attached to one terminal, and the other ends attached to the other terminal), what would be the total current !lowing through the two wires# A) I B) 2 I C) I $) I 32 %) I 3 Answer: A Var: 1
() A light bulb is connected in the circuit shown in the !igure with the switch S open. All the connecting leads have no appreciable resistance and the battery has no internal resistance. "hen we close the switch, which statements below accurately d escribe the behavior o! the circuit# 4here may be more than one correct choice.)
A) he brightness o! the bulb will increase. B) he brightness o! the bulb will decrease. C) he brightness o! the bulb will not change. $) he potential drop across R2 will decrease. %) he potential drop across R2 will not change. Answer: A, $ Var: 1
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5) wo light bulbs, B1 and B2 , are connected to a battery having appreciable internal resistance as shown in the !igure. "hat happens to the brightness o! bulb B1 when we close the switch S #
A) he brightness o! B1 increases permanently. B) he brightness o! B1 decreases permanently. C) he brightness o! B1 does not change. $) he brightness o! B1 increases temporarily but gradually decreases bac to its original brightness. %) he brightness o! B1 decreases temporarily but gradually increases bac to its o riginal brightness. Answer: B Var: 1
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6) A galvanometer G has an internal resistance r g . An A77%%0 is constructed by incorporating the galvanometer and an additional resistance R s. "hich one o! the !igures below is the most appropriate circuit diagram !or the ammeter#
A) 1 B) 2 C) + $) %) Answer: $ Var: 1
8) A galvanometer G has an internal resistance r g . A V97%%0 is constructed by incorporating the galvanometer and an additional resistance R s. "hich one o! the !igures below is the most appropriate circuit diagram !or the voltmeter#
A) 1 B) 2 C) + $) %) Answer: A Var: 1 Copyright & 2'1( earson %ducation, *nc.
1') A resistor and a capacitor are connected in series across an ideal battery having a constant voltage across its terminals. At the moment contact is made with the battery 4a) the voltage across the capacitor is A) e-ual to the battery;s terminal voltage. B) less than the battery;s terminal voltage, but greater than
11) An RC circuit is connected across an ideal $C voltage source through an open switch. he switch is closed at time t = ' s. "hich o! the !ollowing statements regarding the c ircuit are correct# 4here may be more than one correct choice.) A) he capacitor charges to its ma>imum value in one time constant and the current is
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12) A light bulb is connected in the circuit shown in the !igure with the switch S open and the capacitor uncharged. he battery has no app reciable internal resistance. "hich one o! the !ollowing graphs best describes the brightness B o! the bulb as a !unction o! time t a!ter closing the switch#
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A) 1 B) 2 C) + $) %) Answer: B Var: 1
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2 5 . 2 Pr o bl e ms 1) he em! and the internal resistance o! a battery are as shown in the !igure. *! a current o! 6.+ A is drawn !rom the battery when a resistor R is connected across the terminals ab o! the battery, what is the power dissipated by the resistor R#
A) ' " B) 5'' " C) (2' " $) +' " %) 58' " Answer: A Var: 1
2) he em! and the internal resistance o! a battery are as shown in the !igure. "hen the terminal voltage V ab is e-ual to 15. V, what is the current through the battery, including its direction#
A) (.6 A, !rom b to a B) 6.5 A, !rom b to a C) (.6 A, !rom a to b $) 6.5 A, !rom a to b %) 1( A, !rom b to a Answer: A Var: 1
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+) he em! and the internal resistance o! a battery are shown in the !igure. *! a current o! 5.6 A is established through the battery !rom b to a, what is the terminal voltage V ab o! the battery#
A) ?+' V B) 6' V C) +' V $) ?6' V %)
) *n the !igure a current o! (.' A is drawn !rom the battery. "hat is the terminal voltage V ab o! the battery#
A) '.'' V B) @12 V C) @2 V $) ?12 V %) ?2 V Answer: A Var: 1
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) *n the !igure, when the terminal voltage V ab o! the battery is e-ual to 2' V, how much current passes through the battery, including its direction#
A) A, !rom a to b B) A, !rom a to b C) ( A, !rom a to b $) A, !rom b to a %) A, !rom b to a Answer: A Var: 1
() A .'? resistor and a 8.'? resistor are connected in parallel. A .'? resistor is then connected in series with this parallel combination. An ideal (.'?V battery is then connected across the series?parallel combination o! the three resistors. "hat is the current through 4a) the .'? resistor# 4b) the .'? resistor# 4c) the 8.'? resistor# Answer: 4a) '.6+ A 4b) '.+ A 4c) '.+' A Var: 1
5) or the circuit shown in the !igure, determine the current in 4a) the 1.'? resistor. 4b) the +.'? resistor. 4c) the .'? resistor.
Answer: 4a) 2.6 A
4b) 1.2 A
4c) '.8' A
Var: 1
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6) A .''? resistor, an 6.''? resistor, and a 2.'? resistor are connected together. 4a) "hat is the ma>imum resistance that can be produced using all three resistors# 4b) "hat is the minimum resistance that can be produced using all three resistors# 4c) ow would you connect these three resistors to obtain a resistance o! 1'.' # 4d) ow would you connect these three resistors to obtain a resistance o! 6.'' # Answer: 4a) +(.' 4b) 2.' 4c) Connect the 6.''? and 2.'? resistors in parallel and then connect this combination in series with the .''? resistor. 4d) Connect the .''? and 6.''? resistors in series and then connect this combination in parallel with the 2.'? resistor. Var: 1
8) hirteen resistors are connected across points A and B as shown in the !igure. *! all the resistors are accurate to 2 signi!icant !igures, what is the e-uivalent resistance between points A and B#
A) .' B) (.' C) 6.' $) 1' %) 12 Answer: C Var: 1
1') wo unnown resistors are connected together. "hen they are connected in series their e-uivalent resistance is 1 . "hen they are c onnected in parallel, their e-uivalent resistance is +.+ . "hat are the resistances o! these resistors# Answer: .8 and 1' Var: 1
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11) *n the circuit shown in the !igure, an ideal ohmmeter is connected across ab with the switch S open. All the connecting leads have negligible resistance. he reading o! the ohmmeter will be closest to
A) 5. . B) 1' . C) +' . $) ' . %) (' . Answer: A Var: 1
12) hree resistors having resistances o! .' , (.' , and 1'.' are connected in parallel. *! the combination is connected in series with an ideal 12?V battery and a 2.'? resistor, what is the current through the 1'.'? resistor# A) '.8 A B) 2.5 A C) (. A $) 11.2 A %) 1( A Answer: A Var: 1
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1+) hree resistors are connected across an ideal 2.'?V $C battery as shown in the !igure. 4a) At what rate does the battery supply energy to the resistors# 4b) At what rate is heat produced in the (.'? resistor#
Answer: 4a) +.' "
4b) '.(5 "
Var: 1
1) our resistors are connected across an 6?V $C battery as shown in the !igure. he current through the 8? resistor is closest to
A) 1 A. B) '.5 A. C) '. A. $) '.8 A. %) 2 A. Answer: B Var: 1
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1) "hen !our identical resistors are connected to an ideal battery o! voltage V = 1' V as shown in the !igure, the current I is e-ual to '.2' A. "hat is the value o! the resistance R o! the resistors#
A) 2' B) ' C) +' $) ' %) 1' Answer: C Var: 1
1() wo identical resistors o! resistance R = 2 and a variable resistor R x are connected to an ideal battery o! voltage V as shown in the !igure. "hat should be the value o! the variable resistance R x to mae the voltage across the two parallel resistors e-ual to
A) .' B) 2 C) 6.' $) 1( %) ' Answer: C Var: 1 1 Copyright & 2'1( earson %ducation, *nc.
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15) or the circuit shown in the !igure, I = '.' A and R = 12 . "hat is the value o! the em! ε#
A) 16 V B) 2 V C) (.' V $) 12 V %) 6 V Answer: B Var: 1
16) or the circuit shown in the !igure, the current in the 6? resistor is '.' A, and all -uantities are accurate to 2 signi!icant !igures. "hat is the current in the 2? resistor#
A) 2.2 A B) '.5 A C) . A $) 8. A %) (. A Answer: $ Var: 1
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18) or the circuit shown in the !igure, all -uantities are accurate to + signi!icant !igures. "hat is the power dissipated in the 2? resistor#
A) .++ " B) 6.' " C) (.(5 " $) 2.(5 " %) +.( " Answer: % Var: 1
2') "hen a 2'.'?ohm resistor is connected across the terminals o! a 12.'?V battery, the voltage across the terminals o! the battery !alls by '.+'' V. "hat is the internal resistance o! this battery# A) +.(' B) 1.( C) '.86 $) '.+' %) '.1 Answer: % Var: 1
21) "hat is the ma>imum current that can be drawn !rom a 1.'?V battery with an internal resistance o! '.+' ohm# A) 2. A B) .' A C) '. A $) '.2' A %) . A Answer: B Var: 1
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22) "hen a 1''? resistor is connected across the terminals o! a battery o! em! ε and internal resistance r , the battery delivers '.58 " o! power to the 1''? resistor. "hen the 1''? resistor is replaced by a 2''? resistor, the battery delivers '.'1 " o! power to the 2''? resistor. "hat are the em! and internal resistance o! the battery# A) ε = 1'.' V, r = .'2 B) ε = .' V, r = .'' C) ε = 8.'' V, r = 2.' $) ε = 8.'' V, r = 1.'1 %) ε = 12.' V, r = (.'' Answer: $ Var: 1
2+) or the circuit shown in the !igure, what current does the ideal ammeter read#
A) '.'++ A B) '.'56 A C) '.2+ A $) '.12 A Answer: A Var: 1
2) or the circuit shown in the !igure, what is the current through resistor R1#
A) '.'51 A B) '.1+ A C) '.'28 A $) '.'1( A Answer: A Var: 1
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2) or the circuit shown in the !igure, what is the current through resistor R+#
A) '.'+ A B) 1. A C) '.'26 A $) '.'6( A Answer: A Var: 1
2() or the circuit shown in the !igure, determine the current in 4a) the 5.'? resistor. 4b) the 6.'? resistor. 4c) the .'? resistor.
Answer: 4a) 1.( A
4b) 1.+ A
4c) '.26 A
Var: 1
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25) or the circuit shown in the !igure, all -uantities are accurate to 2 signi!icant !igures. "hat is the value o! the current I 1#
A) '.+2 A B) '.11 A C) '.28 A $) '.(1 A %) '.68 A Answer: $ Var: 1
26) A multiloop circuit is shown in the !igure. *t is not necessary to solve the entire circuit. he current I 2 is closest to
A) ?( A. B) ( A. C) 6 A. $) ?6 A. %)
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28) A multiloop circuit is shown in the !igure. *t is not necessary to solve the entire circuit. Compared to the polarity shown in the !igure, the em! ε1 is closest to
A) ? V. B) V. C) V. $) 1 V. %) ?1 V. Answer: A Var: 1
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+') A multiloop circuit is shown in the !igure. ome circuit -uan tities are not labeled. *t is not necessary to solve the entire circuit. he current I 1 is closest to
A)
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+1) A multiloop circuit is shown in the !igure. ome circuit -uan tities are not labeled. *t is not necessary to solve the entire circuit. he em! ε is closest to
A) @+ V. B) @18 V. C) ?+ V. $) ?1' V. %) ?1 V. Answer: B Var: 1
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+2) A multiloop circuit is shown in the !igure. ome circuit -uan tities are not labeled. *t is not necessary to solve the entire circuit. he current I 2 is closest to
A) @'.1 A. B) @'.+ A. C) @'. A. $) ?'.1 A. %) ?'.+ A. Answer: % Var: 1
++) Consider the circuit shown in the !igure. Dote that two currents are shown. Calculate the em!s ε1 and ε+.
Answer: ε1 = 26 V, ε+ = V Var: 1
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+) A galvanometer coil having a resistance o! 2' and a !ull?scale de!lection at 1.' mA is connected in series with a 86' resistance to build a voltmeter. "hat is the ma>imum voltage that this voltmeter can read# A) +.' V B) 1.' V C) ' V $) .' V %) 1' V Answer: $ Var: 1
+) A galvanometer has an internal resistance o! 1'' and de!lects !ull?scale at 2.'' mA. "hat si
+() A galvanometer has a coil with a resistance o! 2.' , and a current o! 16' EA causes it to de!lect !ull scale. *! this galvanometer is to be used to construct an ammeter that can read up to 1'.' A, what shunt resistor is re-uired# A) 12+ F B) 2+ F C) +2 F $) +2 F %) 2+ F Answer: $ Var: 1
+5) A galvanometer has an internal resistance o! 1'' and de!lects !ull?scale at a current o! 2. '' mA. "hat si
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+6) A galvanometer with a resistance o! '.' de!lects !ull scale at a current o! 2.' mA. "hat resistance should be used with this galvanometer in order to construct a voltmeter that can read a ma>imum o! ' V# A) 2 B) 25 C) 28 $) +1 %) + Answer: A Var: 1
+8) *n the circuit shown in the !igure, two +('.'? resistors are connected in series with an ideal source o! em!. A voltmeter with internal resistance o! (+' is connected across one o! the resistors and reads +.2+ V. ind the em! o! the source.
Answer: (.( V Var: 1
') A (.'?E capacitor is connected in series with= .' 7 resistor, and this combination is connected across an ideal 1?V $C battery. "hat is the current in the circuit when the capacitor has reached 2'G o! its ma>imum charge# A) (. EA B) 2. EA C) 1.+ EA $) .5 EA %) 8.1 EA Answer: B Var:
1) A .'?m capacitor is discharged through a .'? resistor. ow long will it tae !or the capacitor to lose hal! its initial stored energy# A) 8.2 s B) 2.5 s C) 1'.2 s $) . s %) 1.( s Answer: $ Var: 2( Copyright & 2'1( earson %ducation, *nc.
2) An uncharged 1.'?E capacitor is connected in series with a battery, and an open switch. "hat is the voltage across the capacitor switch# A) 2.5 V B) 1.( V C) 2.( V $) '.(2 V Answer: A
resistor, an ideal a!ter closing the
Var: '@
+) A .'?E capacitor that is initially uncharged is connected in series with a .'? resistor and an ideal 15.'?V battery. ow much energy is stored in the capacitor 15 ms a!ter the battery has been connected# A) 2',''' nH B) 1,''' H C) 2 FH $) 68' nH Answer: A Var: 1
) or the circuit shown in the !igure, the switch S is initially open and the capacitor is uncharged. he switch is then closed at time t = '. ow many seconds a!ter closing the switch will the energy stored in the capacitor be e-ual to '.2 mH#
A) 61 s B) ( s C) 85 s $) 11' s %) 1+' s Answer: A Var: 1
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) or the circuit shown in the !igure, the switch S is initially open and the capacitor voltage is 6' V. he switch is then closed at time t = '. "hat is the charge on the capacitor when the current in the circuit is ++ EA#
A) 11'' FC B) 1''' FC C) 8(' FC $) 68' FC %) 6+' FC Answer: A Var: 1
() or the circuit shown in the !igure, the switch S is initially open and the capacitor voltage is 6' V. he switch is then closed at time t = '. ow long a!ter closing the switch will the current in the resistor be 5.' FA#
A) 65 s B) 8 s C) 56 s $) (8 s %) (1 s Answer: A Var: 1
5) An uncharged +'.'?F capacitor is connected in series with a 2.'? resistor, a $C battery, and an open switch. he battery has an internal resistance o! 1'.' and the open?circuit voltage across its terminals is '.' V. he leads have no appreciable resistance. At time t = ', the switch is suddenly closed. 4a) "hat is the ma>imum current through the 2.'? resistor and when does it occur 4immediately a!ter closing the switch or a!ter the switch has been closed !or a long time)# 4b) "hat is the ma>imum charge that the capacitor receives# 4c) "hen the current in the circuit is '.6' A, how much charge is on the plates o! the capacitor# Answer: 4a) 1.+ A, immediately a!ter closing the switch 4b) 1'' FC 4c) ('6 FC Var: 1
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6) or the circuit shown in the !igure, the capacitors are all initially uncharged, the connecting leads have no resistance, the battery has no appreciable internal resistance, and the switchS is originally open.
4a) Hust a!ter closing the switch S , what is the current in the 1.'? resistor# A) '.'' A B) 1.(5 A C) 2.' A $) +.++ A %) .'' A 4b) A!ter the switch S has been closed !or a very long time, what is the potential di!!erence across the 26.'?E capacitor# A) '.'' V B) 2.' V C) +.++ V $) +5. V %) '.' V Answer: 4a) A4b) B Var: 1
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