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All Electrical Engineering MCQs

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

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461Electrical EngineeringMedium

A half-wave rectifier has an input voltage of 240 V r.m.s. If the step-down transformer has a turns ratio of 8:1, what is the peak load voltage? Ignore diode drop?

A27.5 V

B42.5 V

C30 V

D86.5 V

Correct answer

B. 42.5 V

Explanation

The correct answer is 42.5 V.

462Electrical EngineeringMedium

Blowing down of boiler water is the process________?

Ato control the solid concentration in the boiler water by removing some of the concentrated saline water

Bnone of the above

Cto reduce the boiler pressure

Dto increase the steam temperature

Correct answer

A. to control the solid concentration in the boiler water by removing some of the concentrated saline water

Explanation

The correct answer is to control the solid concentration in the boiler water by removing some of the concentrated saline water.

463Electrical EngineeringMedium

When the armature of a D.C. motor rotates, e.m.f. induced is________?

Aself-induced e.m.f.

Bback e.m.f

Cnone of the above

Dmutually induced e.m.f.

Correct answer

B. back e.m.f

Explanation

The correct answer is back e.m.f.

464Electrical EngineeringMedium

The spacing between phase conductors of a 220 kV line is approximately equal to________?

A2 m

B8.5 m

C6 m

D3.5 m

Correct answer

C. 6 m

Explanation

The correct answer is 6 m.

465Electrical EngineeringMedium

In series resonance, there is________?

ABoth voltage and current amplification

BCurrent amplification

CVoltage amplification

DNone of the above

Correct answer

C. Voltage amplification

Explanation

The correct answer is Voltage amplification.

466Electrical EngineeringMedium

If load (or torque) angle of a 4-pole synchronous motor is 6° electrical, its value in mechanical degrees is________?

Correct answer

C. 3

Explanation

The correct answer is 3.

467Electrical EngineeringMedium

D.C. machines designed with a large value of air gap length have________?

Apoor ventilation

Bnone of the above

Cbetter ventilation

Dworst, ventilation

Correct answer

C. better ventilation

Explanation

The correct answer is better ventilation.

468Electrical EngineeringMedium

An average voltage of 10 V is induced in a 250 turns solenoid as a result of a change in flux which occurs in 0.5 second. The total flux change is________?

A0.2 Wb

B0.02 Wb

C2 Wb

D20 Wb

Correct answer

B. 0.02 Wb

Explanation

The correct answer is 0.02 Wb.

469Electrical EngineeringMedium

________are used for construction of core of electromagnets?

AEither A. or B.

BNone of the above

CHard magnetic materials

DSoft magnetic materials

Correct answer

D. Soft magnetic materials

Explanation

The correct answer is Soft magnetic materials.

470Electrical EngineeringMedium

Two similar 15 V Zeners are connected in series. What is the regulated output voltage?

A15 V

B30 V

C45 V

D5 V

Correct answer

B. 30 V

Explanation

The correct answer is 30 V.

Blowing down of boiler water is the process________?

Ato control the solid concentration in the boiler water by removing some of the concentrated saline water

Bnone of the above

Cto reduce the boiler pressure

Dto increase the steam temperature

Correct answer

A. to control the solid concentration in the boiler water by removing some of the concentrated saline water

Explanation

The correct answer is to control the solid concentration in the boiler water by removing some of the concentrated saline water.