Test Series Aipmt 2016 Current Electricity

Er. UMVED SINGH (9027187359)

P.L. SHARMA ROAD MEERUT

POTENTIAL TEST SERIES (2016)

IIT-JEE (MAINS)/AIIMS/AIPMT/CPMT

Direction: 1. 2.

.

The Test Booklet consists of 45 questions

Find out the value of current through 2 resistance for the given circuit

There is only one correct answer.

3. You will be awarded 4 Marks if you have darkened only the bubble

10V

20V

10

5

corresponding to the correct answer and zero mark if no bubble is

2

darkened. In all other cases, minus one ( – 1) mark will be awarded.

(A) 5A (B) 2 A (C) zero (D) 4 A . Two bars of radius r and 2r are kept in contact contact as shown. shown. An electric current I is passed through the bars. Which one of following is correct

1. In the circuit shown in the figure, the current through 3

2

9V

2

8

8

½

4

½ r

2r I 2

2

A

(A) the 3 3 resistor is 0.50 A (B) the 3 3 resistor is 0.25 A (C) the 4 4 resistor is 0.50 A (D) the 4 4 resistor is 0.25 A

In the given circuit, it is observed that the current I is independent of the value of the resistance R 6. Then, the resistance values must satisfy R5

R1

I

C

2

R3

B

(A) Heat produced in bar BC is 4 times the heat produced in bar AB (B) Electric field in both halves is equal (C) Current density across AB is double that of across BC (D) Potential difference across AB is 4 times that of across BC Figure shows three resistor configurations R1, R2 and R3 connected to 3V battery. If the power dissipated by the configuration R1, R2 and R3 is P1, P2 and P3, respectively, then

R6

1

1

R2

1

R4

1

3V 1

1

1

1

(A) R1R2R5 = R3R4R6

(B)

(C) R1R4 = R2R3

(D) R1R3 = R2R4

R5



R6



1 R1  R2



1

1

R3  R4

. A 100 W bulb B1, and two 60 W bulbs B 2 and B 3, are

connected to a 250 V source, as shown in the figure. Now W1, W 2 and W 3 are the output powers of the bulbs B1, B2 and B 3 respectively. Then B1

B2

(B) W1 > W2 > W3 (D) W1 < W2 < W3

1

R2

R3

(B) P1 > P3 > P2

(C) P2 > P1 > P3

(D) P3 > P2 > P1

Incandescent bulbs are designed by keeping in mind that the resistance of their filament increases with the increase in temperature. If at room temperature, 100 W, 60 W and 40 W bulbs have filament resistance R 100, R60 and R40, respectively, the relation between these resistances is 1 R100



1 R 40



1 R60

(C) R100 > R60 > R40

TEST SERIES-2016 MEDICAL/ENGG. ENTRANCE EXAM Er. UMVED SINGH (9027187359)

3V

1

1

R1

(A) (A) W1 > W2 = W3 (C) W1 < W2 = W3

1

1

(A) P1 > P2 > P3

B3

250V

3V

1

1

1

ई   

(B) R100 = R40 + R60 (D)

1 R100



1 R60



1 R40

(CURRENT ELECTRICITY)

Dedicated to teaching P.L. SHARMA ROAD, MEERUT

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. In the shown arrangement of the experiment of the meter bridge if AC corresponding to null deflection of galvanometer is x, what would be its value if the radius of the wire AB is doubled? R2

R1

G A

B x

C

(A) x (B) x/4 (C) 4x (D) 2x . A moving coil galvanometer of resistance 100  is used as an ammeter using a resistance 0.1 0.1 . The maximum deflection current in the galvanometer is 100 A. Find the minimum current in the circuit, so that the ammeter shown maximum deflection. (A) 100.1 mA (B) 1000.1 Ma (C) 10.01 mA (D) 1.01 mA To verify Ohm’s law, a student is provided with a test resistor RT, a high resistance R1, a small resistance R2, two identical galvanometers G 1 and G2, and a variable voltage source V. The correct circuit to carry out the experiment is

In a Meter Bridge experiment, null point for an unknown resistance is measured. Now, the unknown resistance is put inside an enclosure maintained at a higher temperature. The null point can be obtained at the same point as before by decreasing the value of the standard resistance. Resistance of a metal increases with increase in temperature. (A) Statement– Statement–1 is True, Statement– Statement–2 is True ; Statement– Statement–2 is a correct explanation for Statement– Statement–1 (B) Statement– Statement–1 is True, Statement– Statement–2 is True ; Statement– Statement–2 is NOT a correct explanation for Statement– Statement–1 (C) Statement– Statement–1 is True, Statement– Statement–2 is False. (D) Statement– Statement–1 is False, Statement– Statement–2 is True. The length of a wire of a potentiometer is 100 cm, and the emf of its stand and cell is E volt. It is employed to measure the emf of a battery whose internal resistance is 0.5  If the balance point is obtained at  = 30 cm from the positive end, the emf of the battery is(1) (2)

(3) (4) (A)

30E 100.5

30E 100  0.5 30(E 30(E  0.5i) 0.5i) 100 30E

, where i is the current in potentiometer wire

100

The length of a given cylindrical wire is increased increased by 100%. Due to the consequent decrease in diameter the change in the resistance of the wire will be-

(B)

(1) 200 %

(2) 100 %

(3) 50 %

(4) 300 %

The thermistor are usually made of (1) metals with low temperature coefficient of resistivity (C)

(D)

(2) metals with high temperature coefficient of r esistivity (3) metal oxides with high temperature coefficient of resistivity

For the circuit shown shown in the figure

I

2k

24V

6k

(4) semiconducting materials having low temperature coefficient of resistivity

R1

R2

RL

In a wheatstone's bridge, three resistances P, Q and R are connected in the three arms and the fourth arm is formed by two resistances S1 and S2 connected in parallel. The

1.5k

condition for the bridge to be balanced will be-

(A) The current I through the battery is 7.5 mA (B) The potential difference across RL is 18 V

(1)

(C) Ratio of powers dissipated in R1 and R2 is 3 (D) If R1 and R2 are interchanged magnitude of the power dissipated in RL will decrease by a f actor of 9

(3)

P Q P Q


ई   

=

=

2R

(2)

S1  S2 R( S1  S2 ) 2S1S2

(4)

P Q P Q

=

=

R( S1  S2 ) S1S2 R S1  S2



Page 2





The resistance of a wire is 5 at 50 C and 6  at 100 C. The resistance of the wire at 0 C will be (1) 2 

(2) 1 

(3) 4 

(4) 3 

This question has Statement I and Statement II. Of the four choice given after the Statements, choose the one that best describes the two S tatement Higher the range, greater is the resistance of ammeter. To increase the ragne of ammeter, additional shunt needs to be used across it.

Consider a block of conducting material of resistive shown in the figure. Current ‘I’ enters at ‘A’ and leaves from ‘D’. We apply superposition principle to find voltage developed between ‘B’ and an d ‘C’. The calculation is done in the following steps

V I

I

(1) Statement-I is true, Statement-II is true, Statement-II is the explanation of Statement-I (2) Statement-I is true, Statement-II is true, Statement-II is the correct explanation of Statement-I. (3) Statement-I is

Statement-II is false.

(4) Statement-I is

Statement-II is true.

(3) 0.5 V/m

A

B

C

D

(i) Take current ‘I’ entering from ‘A’ and assume it to spread over a hemispherical surface in the block. (ii) Calculate field E(r) at distance ‘r’ from A by using Ohm’s law E = , where j is the current per unit area at ‘r’ (iii) From the ‘r’ dependence of E(r), obtain the potential V(r) at r. (iv) Repeat (i), (ii) and (iii) for current ‘I’ leaving ‘D’ and superpose results for ‘A’ and ‘D’ For current entering at A, the electric field at a distance ‘r’ from A is (1) (3)

I 8 r

2

(2)

2

(4)

I 2 r

I r

(4) 0.1 V/m

Two cells, each of e.m.f. E and internal resistance r, are connected in parallel across a resistor R. The power dissipated in the resistor is maximum if : (1) R = r (2) R = 2r 3r r (3) R  (4) R  2 2 22 There are 8.4 10 free electrons per cm 3 in copper. The current in the the wire is 0.21A 0.21A (e = 1.6 × 10–19 C). Then the drifts velocity of electrons in a copper wire of 1 mm 2 cross section, will be (1) 2.12 × 10–5 m/s (2) 0.78  10–5 m/s (3) 1.56  10–5 m/s (4) none of these Copper and silicon are cooled from 300 K to 60K, the specific resistance

2

(1) decrease in copper but increase in silicon

I 2 4 r

(2) increase in copper but decrease in silicon (3) increase in both

V measured between B and C is (1)

(3)

I a



I 2a

I   a  b



I 2  a  b 

(2)

(4)

(4) decrease in both

I a



I

The current voltage graph for a given metallic conductor at two different temperatures T1 and T2 are as shown in the figure. Then :– :–

 a  b

I 2  a  b 

I

T2

If 400  of resistance resistance is made by adding four 100  resistance of tolerance 5%, then the tolerance of the combination is : (1) 20%

(2) 5%

(3) 10%

(4) 15%

(2) Both

(3) 100 W

(4) 25 W

V

(1) T1 > T2

Two electric bulbs marked 25W-220 V and100 W-220 V are connected in series to a 440 V supply. Which of the bulbs will fuse ? (1) Neither

(2) T1 = T2 (3) nothing can be said about about T1 and T2 (4) T1 < T2


T1

ई   



Page 3





Two wires of resistance R1 and R2 at 0

C have

The kirchhoff's first law (i = 0) and second law ( (iR = E),Where the symbols have their usual meanings, are respectively based on-

temperature coefficient of resistance 1 and 2, respectively. These are joined in series. The effective temperature coefficient of resistance is   2 (1) 1 (2) 12 2 (3)

1R1  2 R 2 R1  R 2

(1) conservation of charge, conservation of momentum (2) conservation of energy, conservation of charge (3) conservation of momentum, conservation of charge

R1 R2 12

(4)

2

(4) conservation of charge, conservation of energy

2

R1  R2

If voltage across a bulb rated 220 Volt 100 Watt drops by 2.5% of its rated value, the percentage of the rated value by which the power would decrease is (1) 5%

(2) 10%

(3) 20%

(4) 2.5%

A ring is made of a wire having a resistance R0 = 12 12. Find the points A and B as shown in the figure at which a current carrying conductor should be connected so that the resistance R of the sub circuit 8 . between these points is equal to 3

. The three resistance of equal value are arranged in the different combinations shown below. Arrange them in increasing order of power dissipation :

i

i

i

(A) III < II < IV < I

(B) II < III < IV < I

(C) I < IV < III < II

(D) I < III < II < IV

1

A

In a metre bridge experiment, experiment, null point is obtained at 20 cm from one end of the wire when resistance X is balanced against another resistance Y. If X < Y, then where will be the new position of the null point from the same end, if one decides to balance a resistance of 4X against Y ?

B

2 1

(1)



2 1

(3)

2



3 8 5 8

1

(2)



2

1

(4)

2



1

(1) 50 cm

(2) 80 cm

2

(3) 40 cm

(4) 70 cm

1 3

A cell having an emf  and internal resistance r is connected across a variable external resistance R. As the resistance R is increased, the plot of potential difference V across R is given by 

A 5V battery with internal resistance 2 and a 2V battery with internal resistance1 resistance1 are connected to a 10  resistor as shown in the figure. The current in the 10 10 resistor is P2

5V

V

10

2

2V 1

V

(1)

0

R

(2)

0





V

V

R

P1

(1) 0.27 A P 2 to P1 (3) 0.03 A P 2 to P1

(2) 0.03 A P 1 to (4) 0.27 A P1 to P2

P2

If a wire is stretched to make it 0.1 % longer its resistance will (3)

0

R

(4)

0

R

(1) decrease by 0.2%

(2) decrease by 0.05%

(3) increase by 0.05%

(4) increase by 0.2%


ई   



Page 4





In the shown arrangement of the experiment of the meter bridge if AC corresponding to null deflection of galvanometer is x, what would be its value if the radius of the wire AB is doubled :– :– + R1

In the circuit shown, the current through the 4 4  resistor is 1 amp when the points P and M are connected to a d.c. voltage source. The potential difference between the points M and N is

–

R2

4

G A x

B

C

(1) x

(2)

0.5

(1) 10 C

(2) 24 C

(3) 33 C

(4) 44 C

(1) 0.5 volt

(2) 3.2 volt

(3) 1.5 volt

(4)1.0 volt

See the electrical circuit shown in this figure. Which of the following equations is a correct equation for it R i1

In the circuit shown below. The reading of the voltmeter V is :– :– Rh

2A

1

r1

i2 r2

16 + V

– 16



N

0.5

The current in a conductor varies with time t as I = 2t + 3t2 amp. where I is ampere and t in second. Electric charge flowing through a section of the conductor during t = 2 sec to t = 3 sec is

4

M

x

4 (4) 2x

(3) 4x



P

(1) 1 – (i1 + i2)R + i1r1 = 0

(2) 1 – (i1 + i2)R – i1r1 = 0

(3) 2 – i2r2 – 1 – i1r1 = 0

(4) –2 – (i1 + i2)R + i2r2 = 0

If voltage across a bulb rated 220 Volt 100 Watt drops by 2.5% of its rated value, the percentage of the rated value by which the power would decrease is

4

(1) 12 V (3) 20 V

2

(2) 8 V (4) 16 V

An unknown resistance R1 is connected in series with a

(1) 5%

(2) 10%

resistance of 10 . This combination is connected to one gap of a metre bridge while a resistance R 2 is connected in the other gap. The balance point is at 50 cm. Now, when the 10  resistance is removed the balance point shifts to 40 cm. The value of R 1 is (in ohms)

(3) 20%

(4) 2.5%

Seven resistances are connected as shown in the figure. The equivalent resistance between A and B is :– :–

(1) 20

10 3

A

B

10

(2) 10

5

(3) 60 (4) 40 Five equal resistances each of resistance R are connected as shown in the Figure. A battery of V volts is connected between A and B. The current flowing in AFCEB will be

8

6

6

(1) 3 

(2) 4 

(3) 4.5 

(4) 5 

C

R

D

(1) (3)

V R 2V R

R

R R

F

A

B E

R

(2)

Consider the following two statements: (A) Kirchhoff's junction law follows conservation of charge. (B) Kirchhoff's loop law follows conservation of energy Which of the following is correct? (1) Both (A) and (B) are correct (2) Both (A) and (B) are wrong (3) (A) is correct and (B) is wrong (4) (A) is wrong and (B) is correct

(4)

V 2R 3V R


ई   

from

the

from

the



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Test Series Aipmt 2016 Current Electricity

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