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All Electrical Engineering MCQs

Study 3,658 Electrical Engineering MCQs with correct answers and explanations.

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3171Electrical EngineeringMedium

Which of the following problem arises in D.C. motors which are fed from thyristor bridge circuits?

AIncreased I R losses

BChange in motor parameters

CAll of the above

DPoor commutation

EIncreased core losses

Correct answer

C. All of the above

Explanation

The correct answer is All of the above.

3172Electrical EngineeringMedium

What turn ratio (Np/Ns) of transformer is required to match 4 O speaker to a transistor having an output impedance of 8000 O?

BNone of the above

Correct answer

C. 7

Explanation

The correct answer is 7.

3173Electrical EngineeringMedium

The changes in volume of transformer cooling oil due to variation of atmospheric temperature during day and night is taken care of by which part of transformer?

AConservator

BBuchholz relay

CBreather

DBushings

Correct answer

A. Conservator

Explanation

The correct answer is Conservator.

3174Electrical EngineeringMedium

Which lightening stroke is most dangerous?

AIndirect stroke on conductor

BDirect stroke on tower top

CDirect stroke on ground wire

DDirect stroke on line conductor

Correct answer

D. Direct stroke on line conductor

Explanation

The correct answer is Direct stroke on line conductor.

3175Electrical EngineeringMedium

A synchronous motor develops maximum power when load angle is________?

A120°

B60°

C45°

D90°

Correct answer

D. 90°

Explanation

The correct answer is 90°.

3176Electrical EngineeringMedium

In a squirrel cage motor the induced e.m.f. is________?

Anone of the above

Bdependent on the number of slots

Cdependent on the shaft loading

Dslip times the stand still e.m.f. induced in the rotor

Correct answer

D. slip times the stand still e.m.f. induced in the rotor

Explanation

The correct answer is slip times the stand still e.m.f. induced in the rotor.

3177Electrical EngineeringMedium

The output impedance of a transistor is________?

Avery low

Blow

Czero

Dhigh

Correct answer

D. high

Explanation

The correct answer is high.

3178Electrical EngineeringMedium

If the doping level of a crystal diode is increased, the breakdown voltage________?

Ais decreased

Bis increased

Cremains the same

Dnone of the above

Correct answer

A. is decreased

Explanation

The correct answer is is decreased.

3179Electrical EngineeringMedium

For a consumer the most economical power factor is generally________?

A0.95 lagging

B0.5 lagging

C0.5 leading

D0.95 leading

Correct answer

A. 0.95 lagging

Explanation

The correct answer is 0.95 lagging.

3180Electrical EngineeringMedium

At cut-off, the JFET channel is ________?

Areverse baised

Bcompletely closed by the depletion region

Cextremely narrow

Dat its widest point

Correct answer

B. completely closed by the depletion region

Explanation

The correct answer is completely closed by the depletion region.

3171Electrical EngineeringMedium

Which of the following problem arises in D.C. motors which are fed from thyristor bridge circuits?

AIncreased I R losses

BChange in motor parameters

CAll of the above

DPoor commutation

EIncreased core losses

Correct answer

C. All of the above

Explanation

The correct answer is All of the above.

3172Electrical EngineeringMedium

What turn ratio (Np/Ns) of transformer is required to match 4 O speaker to a transistor having an output impedance of 8000 O?

BNone of the above

Correct answer

C. 7

Explanation

The correct answer is 7.

3173Electrical EngineeringMedium

The changes in volume of transformer cooling oil due to variation of atmospheric temperature during day and night is taken care of by which part of transformer?

AConservator

BBuchholz relay

CBreather

DBushings

Correct answer

A. Conservator

Explanation

The correct answer is Conservator.

3174Electrical EngineeringMedium

Which lightening stroke is most dangerous?

AIndirect stroke on conductor

BDirect stroke on tower top

CDirect stroke on ground wire

DDirect stroke on line conductor

Correct answer

D. Direct stroke on line conductor

Explanation

The correct answer is Direct stroke on line conductor.

3175Electrical EngineeringMedium

A synchronous motor develops maximum power when load angle is________?

A120°

B60°

C45°

D90°

Correct answer

D. 90°

Explanation

The correct answer is 90°.

3176Electrical EngineeringMedium

In a squirrel cage motor the induced e.m.f. is________?

Anone of the above

Bdependent on the number of slots

Cdependent on the shaft loading

Dslip times the stand still e.m.f. induced in the rotor

Correct answer

D. slip times the stand still e.m.f. induced in the rotor

Explanation

The correct answer is slip times the stand still e.m.f. induced in the rotor.

3177Electrical EngineeringMedium

The output impedance of a transistor is________?

Avery low

Blow

Czero

Dhigh

Correct answer

D. high

Explanation

The correct answer is high.

3178Electrical EngineeringMedium

If the doping level of a crystal diode is increased, the breakdown voltage________?

Ais decreased

Bis increased

Cremains the same

Dnone of the above

Correct answer

A. is decreased

Explanation

The correct answer is is decreased.

3179Electrical EngineeringMedium

For a consumer the most economical power factor is generally________?

A0.95 lagging

B0.5 lagging

C0.5 leading

D0.95 leading

Correct answer

A. 0.95 lagging

Explanation

The correct answer is 0.95 lagging.

3180Electrical EngineeringMedium

At cut-off, the JFET channel is ________?

Areverse baised

Bcompletely closed by the depletion region

Cextremely narrow

Dat its widest point

Correct answer

B. completely closed by the depletion region

Explanation

The correct answer is completely closed by the depletion region.