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Electromagnetic Induction

Study 85 Electrical Engineering MCQs with correct answers and explanations.

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31Electrical EngineeringMedium

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

AResistance

BCapacitance

CAll of the above

DInductance

Correct answer

D. Inductance

Explanation

The correct answer is Inductance.

32Electrical EngineeringMedium

Reversing the field or the current will reverse the force on the conductor

ANo

BYes

Correct answer

B. Yes

Explanation

The correct answer is Yes.

33Electrical EngineeringMedium

Two coils have self-inductances of 10 H and 2 H, the mutual inductance being zero. If the two coils are connected in series, the total inductance will be________?

A8 H

B24 H

C6 H

D12 H

Correct answer

D. 12 H

Explanation

The correct answer is 12 H.

34Electrical EngineeringMedium

Lagging of changes in the magnetization of a substance behind changes in the magnetic field as the magnetic field is varied is known as magnetic________?

APermeability

BHysteresis

CRetaintivity

DFlux

Correct answer

B. Hysteresis

Explanation

The correct answer is Hysteresis.

35Electrical EngineeringMedium

Which one of the following functions like a motor?

Aall of above

Bvoltmeter

Cgalvanometer

Dammeter

Correct answer

A. all of above

Explanation

The correct answer is all of above.

36Electrical EngineeringMedium

The polarity of the induced voltage can be determined by using the left-hand generator rule

ANo

BYes

Correct answer

B. Yes

Explanation

The correct answer is Yes.

37Electrical EngineeringMedium

A coil of wire is arranged with its plane perpendicular to a uniform magnetic field o flux density B. when the radius of the coil increases from r1 to r2 in time Δt then what is the emf induced in the coil?

AωB(r2-r1)2/Δt

BωB/r22-r12/Δt

Correct answer

B. ωB/r22-r12/Δt

Explanation

The correct answer is ωB/r22-r12/Δt.

38Electrical EngineeringMedium

If the secondary coil has Ns turns and the primary Np turns the relation between secondary and primary voltages is given by________?

AVs/Vp = Ns/Np

BVp/Vs = Ns/Np

CVp/Vs = Np/Ns

DVs/Vp = Np/Ns

Correct answer

A. Vs/Vp = Ns/Np

Explanation

The correct answer is Vs/Vp = Ns/Np.

39Electrical EngineeringMedium

A laminated iron core has reduced eddy-current losses because________?

Athe magnetic flux is concentrated in the air gap of the core

Bthe laminations are stacked vertfcally

Cthe laminations are insulated from each other

Dmore wire can be used with less D.C. resistance in coil

Correct answer

C. the laminations are insulated from each other

Explanation

The correct answer is the laminations are insulated from each other.

40Electrical EngineeringMedium

The self-inductance of a solenoid is increased when a soft iron core is inserted into it. This is because the soft iron core________?

AReduces the effect of eddy current

BIncreases the mutual inductance between the solenoid and the core

CDecreases the resistance of the solenoid

DImproves the flux linkage between the turns of the coil

Correct answer

D. Improves the flux linkage between the turns of the coil

Explanation

The correct answer is Improves the flux linkage between the turns of the coil.

A laminated iron core has reduced eddy-current losses because________?

Athe magnetic flux is concentrated in the air gap of the core

Bthe laminations are stacked vertfcally

Cthe laminations are insulated from each other

Dmore wire can be used with less D.C. resistance in coil

Correct answer

C. the laminations are insulated from each other

Explanation

The correct answer is the laminations are insulated from each other.

The self-inductance of a solenoid is increased when a soft iron core is inserted into it. This is because the soft iron core________?

AReduces the effect of eddy current

BIncreases the mutual inductance between the solenoid and the core

CDecreases the resistance of the solenoid

DImproves the flux linkage between the turns of the coil

Correct answer

D. Improves the flux linkage between the turns of the coil

Explanation

The correct answer is Improves the flux linkage between the turns of the coil.