JEE Physics Electromagnetic Induction MCQs Set B

Question:

• a) 2 kW
• b) 1 kW
• c) 3 kW
• d) 4 kW

Answer: 2 kW

Question: An ideal solenoid of cross-sectional area 10^–4 m² has 500 turns per metre. At the centre of this solenoid, another coil of 100 turns is wrapped closely around it. If the current in the coil changes from 0 to 2 A in 3.14 ms, the emf developed in the second coil is

• a) 4 mV
• b) 3 mV
• c) 2 mV
• d) 1 mV

Answer: 4 mV

Question: 

• a) First clockwise then anticlockwise
• b) Clockwise
• c) First anticlockwise then clockwise
• d) No current is induced

Answer: First clockwise then anticlockwise

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a)

  

• b)

  

• c) Both the coils have same magnitude of induced emf
• d) Both the coils have same magnitude of magnetic flux

Answer:

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a) 1 : 1
• b) 1 : 4
• c) 1 : 2
• d) 2 : 1

Answer:  1 : 1

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a) 25 V
• b) Zero
• c) 5 V
• d) 10 V

Answer:  25 V

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• b)

  

• c)

  

• d)

  

Answer:

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• a)

  

• b)

  

• c)

  

• d)

  

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• b)

  

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• d)

  

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Question: In an inductor, the current I varies with time t as I = 5A + 16 (A/s) t. If induced emf in the inductor is 5 mV, the self inductance of the inductor is

• a) 3.125 × 10^–4 H
• b) 3.125 × 10^–3 H
• c) 3.75 × 10^–4 H
• d) 3.75 × 10^–3 H

Answer: 3.125 × 10^–4 H

Question:

• a) A to B and D to C
• b) B to A and D to C
• c) B to A and C to D
• d) A to B and C to D

Answer:  A to B and D to C

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a) –21 V
• b) 21 V
• c) 11 V
• d) –11 V

Answer: –21 V

Question: A short-circuited coil is placed in a time-varying magnetic field. Electrical power is dissipated due to the current induced in the coil. If the number of turns were to be quadrupled and the wire radius halved, the electric power dissipated would be

• a) The same
• b) Halved
• c) Doubled
• d) Quadrupled

Answer: The same

Question: A small square loop of wire of side l is placed inside a large circular loops of radius r. The loop are coplanar and their centre coincide. The mutual inductance of the system is proportional to

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a) 0.5 A
• b) 0.1 A
• c) 1 A
• d) 2 A

Answer: 0.5 A

Question: A metal ring is held horizontally and a bar magnet is dropped through the ring with its length along the axis of the ring. The acceleration of the falling magnet is

• a) Less than g
• b) Equal to g
• c) More than g
• d) None of these

Answer: Less than g

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a) QV
• b) 2QV
• c)

  

• d) Zero

Answer: QV

Question:

• a) The circular and the elliptical loops
• b) Only the elliptical loop
• c) The rectangular, circular and elliptical loops
• d) Any of the four loops

Answer: The circular and the elliptical loops

Question: A conducting circular loop is placed in a uniform magnetic field, B = 0.025 T with its plane perpendicular to the loop. The radius of the loop is made to shrink at a constant rate of 1 mms^–1. The induced emf when the radius is 2 cm is

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: A conductor of 3 m length is moving perpendicular to its length as well as a magnetic field of 10^–3 T with a speed of 10² m/s, then the force required to move it with this constant speed is

• a) 0
• b) 0.9 N
• c) 0. 3 N
• d) 3 × 10^–3 N

Answer: 0

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a) 2
• b) 6
• c) 4
• d) 8

Answer: 2

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• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: A long solenoid has 500 turns. When a current of 2 ampere is passed through it, the resulting magnetic flux linked with each turn of the solenoid is 4 × 10^–3 Wb. The self-inductance of the solenoid is

• a) 1.0 henry
• b) 2.0 henry
• c) 2.5 henry
• d) 4.0 henry

Answer: 1.0 henry

Question: In a circular conducting coil, when current increases from 2 A to 18 A in 0.05 s, the induced emf is 20 V. The self inductance of the coil is

• a) 62.5 mH
• b) 6.25 mH
• c) 50 mH
• d) 0

Answer: 62.5 mH

Question:

• a) Maximum in 1, zero in 2
• b) Maximum in both 1 and 2
• c) Zero in 1, maximum in 2
• d) Zero in both 1 and 2

Answer: Maximum in 1, zero in 2

Question:

• a) 2 s
• b) 1 s
• c) 4 s
• d) 3 s

Answer: 2 s

Question: When the number of turns and the length of a solenoid both are doubled, its self inductance becomes

• a) Doubled
• b) Four times
• c) Halved
• d) Unchanged

Answer: Doubled

Question: The time constant of L-R circuit is doubled if

• a) L becomes four times and R becomes two times
• b) L becomes two times and R becomes four times
• c) L becomes two times and R becomes eight times
• d) Both L and R become two times

Answer:  L becomes four times and R becomes two times

Question:

• a) 160 mV
• b) 200 mV
• c) 260 mV
• d) 300 mV

Answer: 160 mV

Question: The self inductance L of a solenoid depends on the number of turns per unit length ‘n’ as

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a) 3.2 × 10^–3 A, 0.16 A
• b) 3.2 × 10^–3 A, 3.2 × 10^–3 A
• c) 0.16 A, 3.2 × 10^–3 A
• d) 0.16 A, 0.16 A

Answer: 3.2 × 10^–3 A, 0.16 A

Question: Two coils of self inductance 2 mH and 8 mH are placed so close together that the effective flux in one coil is completely linked with the other. The mutual inductance between these coils is

• a) 4 mH
• b) 6 mH
• c) 10 mH
• d) 16 mH

Answer:  4 mH

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: A wire loop is rotated in a magnetic field. The frequency of change of direction of the induced e.m.f. is

• a) Twice per revolution
• b) Six times per revolution
• c) Four times per revolution
• d) Once per revolution

Answer: Twice per revolution

Question:

• a)

  

• b)

  

• c)

  

• d) 1

Answer:

Question:

• a) 2rBv and R is at higher potential
• b)

  

• c) Zero
• d)

  

Answer: 2rBv and R is at higher potential