Study mode · no timer

A.C. Fundamentals, Circuits and Circuit Theory

Study 109 Electrical Engineering MCQs with correct answers and explanations.

Answers and explanations are always visible Take this test

71Electrical EngineeringMedium

The equation of 50 Hz current sine wave having r.m.s. value of 60 A is________?

A84.84 sin 3141

B60 sin 50 t

C42.42 sin 314 t

D60 sin 25 t

Correct answer

A. 84.84 sin 3141

Explanation

The correct answer is 84.84 sin 3141.

72Electrical EngineeringMedium

In a three-phase supply floating neutral is undesirable because it way give rise to________?

Aunequal line voltages across the load

Bhigh voltage across the load

Clow voltage across the load

Dminimun voltage across the load

Correct answer

A. unequal line voltages across the load

Explanation

The correct answer is unequal line voltages across the load.

73Electrical EngineeringMedium

Power factor of the following circuit will be zero________?

Acapacitance

Binductance

Cresistance

Dboth B. and C.

Correct answer

D. both B. and C.

Explanation

The correct answer is both B. and C..

74Electrical EngineeringMedium

In a loss-free R-L-C circuit the transient current is________?

Anon-oscillating

Bsinusoidal

Csquare wave

Doscillating

Correct answer

B. sinusoidal

Explanation

The correct answer is sinusoidal.

75Electrical EngineeringMedium

In a pure capacitive circuit if the supply frequency is reduced to 1/2, the current will________?

Abe doubled

Bbe four times at high

Cbe reduced to one fourth

Dbe reduced by half

Correct answer

D. be reduced by half

Explanation

The correct answer is be reduced by half.

76Electrical EngineeringMedium

If two sine waves of the same frequency have a phase difference of JT radians, then________?

Anone of the above

Bboth will reach their maximum values at the same instant

Cwhen one wave reaches its maxi¬mum value, the other will reach its minimum value

Dboth will reach their minimum values at the same instant

Correct answer

C. when one wave reaches its maxi¬mum value, the other will reach its minimum value

Explanation

The correct answer is when one wave reaches its maxi¬mum value, the other will reach its minimum value.

77Electrical EngineeringMedium

The safest value of current the human body can carry for more than 3 second is________?

A4 mA

B25 mA

C15 mA

D9 mA

Correct answer

D. 9 mA

Explanation

The correct answer is 9 mA.

78Electrical EngineeringMedium

Which of the following coil will have large resonant frequency ________?

AA coil with low distributed capacitance

BA coil with low resistance

CA coil with large resistance

DA coil with large distributed capacitance

Correct answer

D. A coil with large distributed capacitance

Explanation

The correct answer is A coil with large distributed capacitance.

79Electrical EngineeringMedium

In a highly capacitive circuit the________?

Aactual power is more than its reactive power

Breactive power is more than the actual power

Creactive power is more than the apparent power

Dapparent power is equal to the actual power

Correct answer

B. reactive power is more than the actual power

Explanation

The correct answer is reactive power is more than the actual power.

80Electrical EngineeringMedium

What will be the phase angle between two alternating waves of equal frequency, when one wave attains maximum value the other is at zero value________?

A45°

B180°

C90°

D0°

Correct answer

C. 90°

Explanation

The correct answer is 90°.

If two sine waves of the same frequency have a phase difference of JT radians, then________?

Anone of the above

Bboth will reach their maximum values at the same instant

Cwhen one wave reaches its maxi¬mum value, the other will reach its minimum value

Dboth will reach their minimum values at the same instant

Correct answer

C. when one wave reaches its maxi¬mum value, the other will reach its minimum value

Explanation

The correct answer is when one wave reaches its maxi¬mum value, the other will reach its minimum value.

In a highly capacitive circuit the________?

Aactual power is more than its reactive power

Breactive power is more than the actual power

Creactive power is more than the apparent power

Dapparent power is equal to the actual power

Correct answer

B. reactive power is more than the actual power

Explanation

The correct answer is reactive power is more than the actual power.