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A.C. Fundamentals, Circuits and Circuit Theory

Study 109 Electrical Engineering MCQs with correct answers and explanations.

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51Electrical EngineeringMedium

In an AC. circuit, a low value of kVAR compared with kW indicates________?

Aunity power factor

Bmaximum load current

Clow efficiency

Dhigh power factor

Correct answer

D. high power factor

Explanation

The correct answer is high power factor.

52Electrical EngineeringMedium

The best place to install a capacitor is________?

Aacross the terminals of the inductive load

Bfar away from the inductive load

Cvery near to inductive load

Dany where

Correct answer

A. across the terminals of the inductive load

Explanation

The correct answer is across the terminals of the inductive load.

53Electrical EngineeringMedium

The power is measured in terms of decibles in case of________?

Aauto transformers

Btransformers

Celectronic equipment

Dcurrent transformers

Correct answer

C. electronic equipment

Explanation

The correct answer is electronic equipment.

54Electrical EngineeringMedium

The product of apparent power and cosine of the phase angle between circuit voltage and current is

Areactive power

Bvolt-amperes

Ctrue power

Dinstantaneous power

Correct answer

C. true power

Explanation

The correct answer is true power.

55Electrical EngineeringMedium

The time constant of a series R-C circuit is given by________?

ARC2

BR2C

CR/C

DRC

Correct answer

D. RC

Explanation

The correct answer is RC.

56Electrical EngineeringMedium

Power factor of the system is kept high________?

Adue to all above reasons

Bto reduce voltage regulation of the line

Cto maximise the utilization of the capacities of generators, lines and transformers

Dto reduce line losses

Correct answer

A. due to all above reasons

Explanation

The correct answer is due to all above reasons.

57Electrical EngineeringMedium

All definitions of power factor of a series R-L-C circuit are correct except________?

Aratio of net reactance and impedance

Bratio of W and VA

Cratio of kW and kVA

Dratio of J and Z

Correct answer

A. ratio of net reactance and impedance

Explanation

The correct answer is ratio of net reactance and impedance.

58Electrical EngineeringMedium

The form factor is the ratio of________?

Apeak value to r.m.s. value

Baverage value to r.m.s. value

Cr.m.s. value to average value

Dnone of the above

Correct answer

C. r.m.s. value to average value

Explanation

The correct answer is r.m.s. value to average value.

59Electrical EngineeringMedium

The series and parallel resonance on L-C circuit’ differs in that________?

Aparallel resonance needs a low-resistance source for a sharp in¬crease in impedance

Bparallel resonance needs a low-resistance source for a sharp rise in line current

Cseries resistance needs a low-resistance source for sharp rise in current

Dseries resonance needs a high-resistance source for sharp increase in current

Correct answer

C. series resistance needs a low-resistance source for sharp rise in current

Explanation

The correct answer is series resistance needs a low-resistance source for sharp rise in current.

60Electrical EngineeringMedium

The ratio of active power to apparent power is known as factor________?

Aload

Bdemand

Cform

Dpower

Correct answer

D. power

Explanation

The correct answer is power.

The series and parallel resonance on L-C circuit’ differs in that________?

Aparallel resonance needs a low-resistance source for a sharp in¬crease in impedance

Bparallel resonance needs a low-resistance source for a sharp rise in line current

Cseries resistance needs a low-resistance source for sharp rise in current

Dseries resonance needs a high-resistance source for sharp increase in current

Correct answer

C. series resistance needs a low-resistance source for sharp rise in current

Explanation

The correct answer is series resistance needs a low-resistance source for sharp rise in current.