Chapter:

# 40+ Electromagnetic Induction Solved MCQs

Chapters

35
57.4k
Chapter: Electromagnetic Induction
1.

## The property of coil by which a counter e.m.f. is induced in it when the current through the coil changes is known as

A. self-inductance
B. mutual inductance
C. series aiding inductance
D. capacitance
2.

## As per Faraday's laws of electromagnetic induction, an e.m.f. is induced in a conductor whenever it

A. lies perpendicular to the magnetic flux
B. lies in a magnetic field
C. cuts magnetic flux
D. moves parallel to the direction of the magnetic field
3.

## Which of the following circuit element stores energy in the electromagnetic field ?

A. Inductance
B. Condenser
C. Variable resistor
D. Resistance
4.

## The inductance of a coil will increase under all the following conditions except

A. when more length for the same number of turns is provided
B. when the number of turns of the coil increase
C. when more area for each turn is provided
D. when permeability of the core increases
Answer» A. when more length for the same number of turns is provided
5.

## Higher the self-inductance of a coil,

A. lesser its weber-turns
B. lower the e.m.f. induced
C. greater the flux produced by it
D. longer the delay in establishing steady current through it
6.

## In an iron cored coil the iron core is removed so that the coil becomes an air cored coil. The inductance of the coil will

A. increase
B. decrease
C. remain the same
D. initially increase and then decrease
7.

## An open coil has

A. zero resistance and inductance
B. infinite resistance and zero inductance
C. infinite resistance and normal inductance
D. zero resistance and high inductance
Answer» B. infinite resistance and zero inductance
8.

A. unaffected
B. doubled
C. halved
9.

## If current in a conductor increases then according to Lenz's law self-induced voltage will

A. aid the increasing current
B. tend to decrease the amount of cur-rent
C. produce current opposite to the in-creasing current
D. aid the applied voltage
Answer» C. produce current opposite to the in-creasing current
10.

## The direction of incViced e.m.f. can be found by

A. Laplace's law
B. Lenz's law
C. Fleming's right hand rule
D. Kirchhoff s voltage law
11.

## Air-core coils are practically free from

A. hysteresis losses
B. eddy current losses
C. both (a) and (b)
D. none of the above
Answer» C. both (a) and (b)
12.

## The magnitude of the induced e.m.f. in a conductor depends on the

A. flux density of the magnetic field
B. amount of flux cut
D. rate of change of flux-linkages
13.

## Mutually inductance between two magnetically-coupled coils depends on

A. permeability of the core
B. the number of their turns
C. cross-sectional area of their com-mon core
D. all of the above
Answer» D. all of the above
14.

## A laminated iron core has reduced eddy-current losses because

A. more wire can be used with less D.C. resistance in coil
B. the laminations are insulated from each other
C. the magnetic flux is concentrated in the air gap of the core
D. the laminations are stacked vertf-cally
Answer» B. the laminations are insulated from each other
15.

B. Lenz
C. Newton
D. Coulomb
16.

## Which of the following is not a unit of inductance ?

A. Henry
B. Coulomb/volt ampere
C. Volt second per ampere
D. All of the above
17.

## In case of an inductance, current is proportional to

A. voltage across the inductance
B. magnetic field
C. both (a) and (b)
D. neither (a) nor (b)
18.

## Which of the following circuit elements will oppose the change in circuit current ?

A. Capacitance
B. Inductance
C. Resistance
D. All of the above
19.

## For a purely inductive circuit which of the following is true ?

A. Apparent power is zero
B. Relative power is.zero
C. Actual power of the circuit is zero
D. Any capacitance even if present in the circuit will not be charged
Answer» C. Actual power of the circuit is zero
20.

A. Ohm
B. Henry
C. Ampere turns
D. Webers/metre
21.

A. 64 A/s
B. 32 A/s
C. 16 A/s
D. 4 A/s
22.

A. 3 mH
B. 12 mH
C. 24mH
D. 48mH
23.

A. 4 mH
B. 5 mH
C. 6 mH
D. 12 mH
24.

A. 32 mH
B. 38 mH
C. 40 mH
D. 48 mH
25.

A. 6 mH
B. 14 mH
C. 24 mH
D. 48 mH
26.

A. 6 H
B. 8 H
C. 12 H
D. 24 H
27.

A. 2.0
B. 1.0
C. 0.5
D. zero
28.

A. 50 ohms
B. 500 ohms
C. 1000 ohms
D. 5000 ohms
29.

A. 10 V
B. 15 V
C. 25V
D. 50V
30.

## Lenz's law is a consequence of the law of conservation of

A. induced current
B. charge
C. energy
D. induced e.m.f.
31.

A. 50 N
B. 120 N
C. 240 N
D. 480 N
32.

A. 100 N
B. 400 N
C. 600 N
D. 1000 N
33.

## The co-efficient of coupling between two air core coils depends on

A. self-inductance of two coils only
B. mutual inductance between two coils only
C. mutual inductance and self inductance of two coils
D. none of the above
Answer» C. mutual inductance and self inductance of two coils
34.

A. 20 Wb
B. 2 Wb
C. 0.2 Wb
D. 0.02 Wb
35.

A. 0.01 s
B. 0.1 s
C. 0.5 s
D. 5 s
36.

## Which of the fpllowing inductor will have the least eddy current losses ?

A. Air core
B. Laminated iron core
C. Iron core
D. Powdered iron core
37.

A. 3500 mH
B. 350 mH
C. 250 mH
D. 150 mH
38.

A. 300 uH
B. 600 uH
C. 150 uH
D. 75 uH
39.

A. 5 mH
B. 10 mH
C. 5 H
D. 10 H
40.

## Which circuit element(s) will oppose the change in circuit current ?

A. Resistance only
B. Inductance only
C. Capacitance only
D. Inductance and capacitance
41.

## A crack in the magnetic path of an inductor will result in

A. unchanged inductance
B. increased inductance
C. zero inductance
D. reduced inductance
42.

## A coil is wound on iron core which carries current I. The self-induced voltage in the coil is not affected by

A. variation in coil current
B. variation in voltage to the coil
C. change of number of turns of coil
D. the resistance of magnetic path
Answer» B. variation in voltage to the coil
43.

A. Yes
B. No
C. none
D. none
44.

A. Yes
B. No
C. none
D. none
45.

A. Yes
B. No
C. none
D. none
46.

A. Yes
B. No
C. none
D. none
47.

A. Yes
B. No
C. none
D. none