# Electromagnetic Induction Class 12 MCQ Questions with Answers

Electromagnetic Induction Class 12 MCQ is one of the best strategies to prepare for the CBSE Class 12 Board exam. If you want to complete a grasp concept or work on one’s score, there is no method except constant practice. Students can improve their speed and accuracy by doing more Electromagnetic Induction Class 12 which will help them all through their board test.

## Electromagnetic Induction Class 12 MCQ Questions with Answers

Class 12 Physics MCQ with answers are given here to Moving Charges and Magnetism. These MCQs are based on the latest CBSE board syllabus and relate to the latest Class 12 Physics syllabus. By Solving these Class 12 MCQs, you will be able to analyze all of the concepts quickly in the chapter and get ready for the Class 12 Annual exam.

Learn Class 12 Electromagnetic Induction MCQ Questions with Answers PDF download according to the latest CBSE and NCERT syllabus. Students should prepare for the examination by solving CBSE MCQ on Electromagnetic Induction Class 12 PDF given below.

Question 1. The current in self inductance L = 40 mH is to be increased uniformly from 1 amp to 11 amp in 4 milliseconds. The e.m.f. induced in inductor during process is
(a) 100 volt
(b) 0.4 volt
(c) 4.0 volt
(d) 440 volt

A

Question 2. A coil of copper having 1000 turns is placed in a magnetic field (B = 4 × 10–5) perpendicular to its axis. The cross sectional area of the coil is 0.05 m2. If it turns through 180° in 0.01 second, then the e.m.f. induced in the coil will be ;
(a) 4 V
(b) 0.04 V
(c) 0.4 V
(d) 0.2 V

C

Question 3. In a coil of self inductance of 5 henry, the rate of change of current is 2 ampere per second, the e.m.f. induced in the coil is :
(a) 5 V
(b) – 5V
(c) – 10 V
(d) 10 V

C

Question 4. An inductor may store energy in
(a) its electric field
(b) its coils
(c) its magnetic field
(d) both in electric and magnetic fields

C

Question 5. A 50 turn circular coil has a radius of 3 cm, it is kept in a magnetic field acting normal to the area of the coil. The magnetic field B is increased from 0.10 T to 0.35 T in 2 milli second, the average induced emf will be:
(a) 177 V
(b) 1.77 V
(c) 0.177 V
(d) 17.7 V

B

Question 6. According to Lenz’s law there is a conversion of:
(a) momentum
(b) collision
(c) voltage
(d) energy

D

Question 7. The flux linked with a coil at any instant ‘t’ is given by f = 10t2 – 50t + 250. The induced emf at t = 3s is
(a) –190 V
(b) –10 V
(c) 10 V
(d) 190 V

B

Question 8. A solenoid is 1.5 m long and its inner diameter is 4.0 cm. It has 3 layers of windings of 1000 turns each and carries a current of 2.0 amperes. The magnetic flux for a cross-section of the solenoid is nearly
(a) 4.1´10-5 weber
(b) 5.2´10-5 weber
(c) 6.31´10-3 weber
(d) 2.5´10-7 weber

C

Question 9. A conducting ring of radius 1 metre is placed in an uniform magnetic field B of 0.01 tesla oscillating with frequency 100 Hz with its plane at right angle to B. What will be the induced electric field ?
(a) pvolt /m
(b) 2volt /m
(c) 10 volt/m
(d) 62 volt/m

B

Question 10. In an AC generator, a coil with N turns, all of the same area A and total resistance R, rotates with frequency w in a magnetic field B. The maximum value of emf generated in the coil is
(a) N.A.B.R.w
(b) N.A.B.
(c) N.A.B.R.
(d) N.A.B.w

D

Question 11. The magnetic flux through a circuit carrying a current of 2.0 A is 0.8 weber. If the current reduces to 1.5 A in 0.1 s, the induced emf be :
(a) 2.0 V
(b) 4.0 V
(c) 8.0 V
(d) none of the above

A

Question 12. A wheel with ten metallic spokes each 0.50m long is rotated with a speed of 120 rev/min in a plane normal to the earth’ s magnetic field at the place.
If the magnitude of the field is 0.40 G, the induced emf between the axle and the rim of the wheel is equal to
(a) 1.256 × 10 – 3 V
(b) 6.28 × 10 – 4 V
(c) 1.256 × 10 – 4 V
(d) 6.28 × 10 – 5 V

D

Question 13. In an inductor of self-inductance L = 2 mH, current changes with time according to relation i = t2e–t. At what time emf is zero?
(a) 4s
(b) 3s
(c) 2s
(d) 1s

C

Question 14. A circular disc of radius 0.2 meter is placed in a uniform magnetic field of induction  1/∏ (Wb /m2) in such a way that its axis makes an angle of 60° with B. The magnetic flux linked with the disc is
(a) 0.08 Wb
(b) 0.01 Wb
(c) 0.02 Wb
(d) 0.06 Wb

C

Question 15. A charged particle moves through a magnetic field in a direction perpendicular to it. Then the
(a) velocity remains unchanged
(b) speed of the particle remains unchanged
(c) direction of the particle remains unchanged
(d) acceleration remains unchanged

B

Question 16. A coil of resistance 400 W is placed in a magnetic field. If the magnetic flux f (Wb) linked with the coil varies with time t (sec) as f = 50t2 + 4. The current in the coil at t = 2 sec is
(a) 0.5 A
(b) 0.1 A
(c) 2 A
(d) 1 A

A

Question 17. A 800 turn coil of effective area 0.05 m2 is kept perpendicular to a magnetic field 5 × 10–5 T. When the plane of the coil is rotated by 90° around any of its coplanar axis in 0.1 s, the emf induced in the coil will be
(a) 0.02 V
(b) 2 V
(c) 0.2 V
(d) 2 × 10–3 V

A

Question 18. A rectangular coil of 20 turns and area of cross-section 25 sq. cm has a resistance of 100 W. If a magnetic field which is perpendicular to the plane of coil changes at a rate of 1000 tesla per second, the current in the coil is
(a) 1 A
(b) 50 A
(c) 0.5 A
(d) 5 A

C

Question 19. 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 mm s–1. The induced emf when the radius is 2 cm, is
(a) 2Π μV
(b) Π μV
(c) Π/2 μV
(d) 2 μV

B

Question 20. A metal ring is held horizontally and bar magnet is dropped through the ring with its length along the axis of the ring. The acceleration of the falling magnet is
(a) more than g
(b) equal to g
(c) less than g
(d) either(a) or (c)

C

Question 21. A magnetic field of 2 × 10–2 T acts at right angles to a coil of area 100 cm2, with 50 turns. The average e.m.f. induced in the coil is 0.1 V, when it is removed from the field in t sec. The value of t is
(a) 10 s
(b) 0.1 s
(c) 0.01 s
(d) 1 s

B

Question 22. 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) 16 mH
(b) 10 mH
(c) 6 mH
(d) 4 mH

D

Question 23. Faraday’s laws are consequence of conservation of
(a) energy
(b) energy and magnetic field
(c) charge
(d) magnetic field

A

Question 24. A straight line conductor of length 0.4 m is moved with a speed of 7 m/s perpendicular to a magnetic field of intensity 0.9 Wb/m2. The induced e.m.f. across the conductor is
(a) 5.04 V
(b) 25.2 V
(c) 1.26 V
(d) 2.52 V

D

Question 25. A long solenoid of diameter 0.1 m has 2 × 104 turns per meter. At the centre of the solenoid, a coil of 100 turns and radius 0.01 m is placed with its axis coinciding with the solenoid axis. The current in the solenoid reduces at a constant rate to 0 A from 4 A in 0.05 s. If the resistance of the coil is 10 p2 W, the total charge flowing through the coil during this time is
(a) 16 mC
(b) 32 mC
(c) 16p mC
(d) 32p mC

B

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Question 26. A cycle wheel of radius 0.5 m is rotated with constant angular velocity of 10 rad/s in a region of magnetic field of 0.1 T which is perpendicular to the plane of the wheel. The EMF generated between its centre and the rim is
(a) 0.25 V
(b) 0.125 V
(c) 0.5 V
(d) zero

B

Question 27. The magnetic flux through a circuit of resistance R changes by an amount Df in a time Dt. Then the total quantity of electric charge Q that passes any point in the circuit during the time Dt is represented by
(a) Q = 1/R . ΔΦ /Δt
(b) Q = ΔΦ/R
(c) Q = ΔΦ /Δt
(d) Q= R.ΔΦ /Δt

B

Question 28. A generator has an e.m.f. of 440 Volt and internal resistance of 4000 hm. Its terminals are connected to a load of 4000 ohm. The voltage across the load is
(a) 220 volt
(b) 440 volt
(c) 200 volt
(d) 400 volt

D

C

Question 29. In a coil of area 10 cm2 and 10 turns with magnetic field directed perpendicular to the plane and is changing at the rate of 108 Gauss/second. The resistance of the coil is 20Ω. The current in the coil will be
(a) 0.5 A
(b) 5 A
(c) 50 A
(d) 5 × 108 A

B

Question 30. A copper disc of radius 0.1 m rotated about its centre with 10 revolutions per second in a uniform magnetic field of 0.1 tesla with its plane perpendicular to the field. The e.m.f. induced across the radius of disc is

(a)$\frac{\pi}{10}$volt

(b)$\frac{2\pi}{10}$ volt

(c)$\pi\times 10^{-2}$volt

(d)$2\pi\times 10^{-2}$ volt

C

Question 31. In which of the following devices, the eddy current
effect is not used?
(a) electric heater
(b) induction furnace
(c) magnetic braking in train
(d) electromagnet

A

Question 32. Eddy currents are produced when
(a) a metal is kept in varying magnetic field
(b) a metal is kept in steady magnetic field
(c) a circular coil is placed in a magnetic field
(d) current is passed through a circular coil

A

Question 33. A coil has 200 turns and area of 70 cm2. The magnetic field perpendicular to the plane of the coil is 0.3 Wb/m2 and take 0.1 sec to rotate through 180º.The value of the induced e.m.f. will be
(a) 8.4 V
(b) 84 V
(c) 42 V
(d) 4.2 V

A

Question 34. A 100 millihenry coil carries a current of 1 ampere. Energy stored in its magnetic field is
(a) 0.5 J
(b) 1 J
(c) 0.05 J
(d) 0.1 J

C

Question 35. The magnetic potential energy stored in a certain inductor is 25 mJ, when the current in the inductor is 60 mA. This inductor is of inductance
(a) 0.138 H
(b) 138.88 H
(c) 1.389 H
(d) 13.89 H

D

Question 36. A current of 2.5 A flows through a coil of inductance 5 H. The magnetic flux linked with the coil is
(a) 0.5 Wb
(b) 12.5 Wb
(c) zero
(d) 2 Wb

B

Question 37. The armature of a dc motor has 20W resistance. It draws a current of 1.5 A when run by a 220 V dc supply. The value of the back emf induced in it is
(a) 150 V
(b) 170 V
(c) 180 V
(d) 190 V

D

Question 38. A coil having 500 square loops each of side 10 cm is placed normal to a magnetic field which increases at the rate of 1 Wb/m2. The induced e.m.f. is
(a) 0.1 V
(b) 5.0 V
(c) 0.5 V
(d) 1.0 V

B

Question 39. 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) 4.0 henry
(c) 2.5 henry
(d) 2.0 henry

A

Question 40. The flux linked with a coil at any instant ‘t’ is given by Ø = 10t2 – 50t + 250. The induced emf at t = 3s is
(a) –190 V
(b) –10 V
(c) 10 V
(d) 190 V

B

Question 41. The self inductance of the motor of an electric fan is 10 H. In order to impart maximum power at 50 Hz, it should be connected to a capacitance of
(a) 8μF
(b) 4μF
(c) 2μF
(d) 1μF

D

Question 42. Two coils have a mutual inductance 0.005 H. The current changes in the first coil according to equation I = I0 sinwt, where I0 = 10 A and w = 100p rad/sec. The maximum value of e.m.f. in the second coil is
(a) p
(b) 5p
(c) 2p
(d) 4p

B

Question 43. For a coil having L = 2 mH, current flow through it is I = t2e–t then, the time at which emf becomes zero
(a) 2 sec
(b) 1 sec
(c) 4 sec
(d) 3 sec.

A

Question 44. What is the self-inductance of a coil which produces 5 V when the current changes from 3 ampere to 2 ampere in one millisecond?
(a) 5000 henry
(b) 5 milli-henry
(c) 50 henry
(d) 5 henry

B

Question 45. If N is the number of turns in a coil, the value of self inductance varies as
(a) N 0
(b) N
(c) N 2
(d) N–2

C

Question 46. In a region of magnetic induction B = 10–2 tesla, a circular coil of radius 30 cm and resistance p2 ohm is rotated about an axis which is perpendicular to the direction of B and which forms a diameter of the coil. If the coil rotates at 200 rpm the amplitude of the alternating current induced in the coil is
(a) 4p2 mA
(b) 30 mA
(c) 6 mA
(d) 200 mA

C

Question 47. A wire loop is rotated in a magnetic field. The frequency of change of direction of the induced e.m.f. is
(a) four times per revolution
(b) six times per revolution
(c) once per revolution
(d) twice per revolution

D

Question 48. A 100 millihenry coil carries a current of 1A. Energy stored in its magnetic field is
(a) 0.5 J
(b) 1 J
(c) 0.05 J
(d) 0.1 J

C

Question 49. If the number of turns per unit length of a coil of solenoid is doubled, the self-inductance of the solenoid will
(a) remain unchanged
(b) be halved
(c) be doubled
(d) become four times

D

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