A.C Fundamentals, Circuits and Circuit Theory MCQs

Question 1

A phasor is

Accepted Answer

A line which represents the magnitude and phase of an alternating quantity

Answer

A line representing the magnitude and direction of an alternating quantity

Answer

A colored tag or band for distinction between different phases of a 3-phase supply

Answer

An instrument used for measuring phases of an unbalanced 3-phase load

Question 2

At __________ frequencies the parallel R-L circuit behaves as purely resistive.

Accepted Answer

Very high

Answer

Low

Answer

Very low

Answer

High

Question 3

In AC. circuits, laminated iron is invariably used in order to

Accepted Answer

Reduce eddy current loss

Answer

Increase heat radiation

Answer

Make assembly cheap and easier

Answer

Reduce circuit permeability

Question 4

The power factor of a D.C. circuit is always

Accepted Answer

Unity

Answer

Less than unity

Answer

Greater than unity

Answer

Zero

Question 5

A pure inductance connected across 250 V, 50 Hz supply consumes 100 W. This consumption can be attributed to

Accepted Answer

The statement given is false

Answer

The big size of the inductor

Answer

The reactance of the inductor

Answer

The current flowing in the inductor

Question 6

In a series resonant circuit, the impedance of the circuit is

Accepted Answer

Minimum

Answer

Maximum

Answer

Zero

Answer

None of the above

Question 7

In series resonant circuit, increasing inductance to its twice value and reducing capacitance to its half value

Accepted Answer

Will increase the selectivity of the circuit

Answer

Will change the maximum value of current at resonance

Answer

Will change the resonance frequency

Answer

Will change the impedance at resonance frequency

Question 8

Power factor of the following circuit will be zero

Accepted Answer

Both B and C

Answer

Resistance

Answer

Inductance

Answer

Capacitance

Question 9

Form Factor is the ratio of

Accepted Answer

$$\frac{{{	ext{Root Mean Square value}}}}{{{	ext{Average value}}}}$$

Answer

$$\frac{{{	ext{Average value}}}}{{{	ext{Root Mean Square value}}}}$$

Answer

$$\frac{{{	ext{Average value}}}}{{{	ext{Peak value}}}}$$

Answer

$$\frac{{{	ext{Root Mean Square value}}}}{{{	ext{Peak value}}}}$$