Electromagnetic Induction Multiple Choice Questions and Answers

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

View Answer

Answer: self-inductance

2 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

View Answer

Answer: when more length for the same number of turns is provided

3 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

View Answer

Answer: longer the delay in establishing steady current through it

4 Both the number of turns and the core length of an inductive coil are doubled. Its self-inductance will be

A unaffected

B doubled

C halved

D None of the above

View Answer

Answer: doubled

5 The direction of induced e.m.f. can be found by

A Laplace’s law

B Lenz’s law

C Fleming’s right hand rule

D All of the above

View Answer

Answer: Lenz’s law

6 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

C amount of flux linkages

D rate of change of flux-linkages

View Answer

Answer: rate of change of flux-linkages

7 The law that the induced e.m.f. and current always oppose the cause producing them is due to

A Faraday

B Lenz

C Newton

D None Of The Above

View Answer

Answer: Lenz

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

A Capacitance

B Inductance

C Resistance

D None of these

View Answer

Answer: Inductance

9 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 None of the Above

View Answer

Answer: Actual power of the circuit is zero

10 The core of a coil has a length of 200 mm. The inductance of coil is 6 mH. If the core length is doubled, all other quantities, remaining the same, the inductance will be

A 3 mH

B 12 mH

C 24mH

D None Of The Above

View Answer

Answer: 3 mH

11 Two coils have inductances of 8 mH and 18 mH and a co-efficient of coupling of 0.5. If the two coils are connected in series aiding, the total inductance will be

A 32 mH

B 38 mH

C 40 mH

D None of the Above

View Answer

Answer: 38 mH

12 A coil with negligible resistance has 50V across it with 10 mA. The inductive reactance is

A 50 ohms

B 500 ohms

C 5000 ohms

D None of the above

View Answer

Answer: 5000 ohms

13 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

View Answer

Answer: mutual inductance and self inductance of two coils

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

A Air core

B Laminated iron core

C Iron core

D All of the above

View Answer

Answer: Air core

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

A Resistance only

B Inductance only

C Capacitance only

D None of these

View Answer

Answer: Inductance only

16 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 None of the above

View Answer

Answer: variation in voltage to the coil

17 An E.M.F. can be induced by _________

A Change in the magnetic field only

B Change in the area of cross section only

C Change in angle between magnetic field and area only

D Change in the magnetic field, area or angle between them

View Answer

Answer: Change in the magnetic field, area or angle between them

18 The total number of magnetic field lines passing through an area is termed as?

A Voltage

B EMF

C Magnetic flux

D None of the above

View Answer

Answer: Magnetic flux

19 If a conductor 0.2m long moves with a velocity of 0.3m/s in a magnetic field of 5T, calculate the emf induced if magnetic field, velocity and length of conductor are mutually perpendicular to each other.

A 0.3V

B 0.03V

C 30V

D None of the above

View Answer