AC Circuits - MCQTrip

Test your knowledge of AC circuits with these multiple choice questions. Learn more about AC circuits and how to solve them with our online MCQs. Twenty (20) MCQ questions from our test bank will be randomly shown for every attempt. Passing mark for this test is 70%.

Objectives: To provide an online quiz to test knowledge of AC circuits and to provide an overview of AC circuits and how to solve them.

Welcome to your AC Circuits MCQ practice assessment.

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

will change the maximum value of current at resonance

will increase the selectivity of the circuit

will change the resonance frequency

will change the impedance at resonance frequency

None

Pure inductive circuit takes power from the A.C. line when

both applied voltage and current decrease

applied voltage increases but current decreases

both applied voltage and current increase

applied voltage decreases but current increases

None

Capacitive reactance is more when

capacitance is less and frequency of supply is more

capacitance is less and frequency of supply is less

capacitance is more and frequency of supply is more

capacitance is more and frequency of supply is less

None

The reactance offered by a capacitor to alternating current of frequency 50 Hz is 20 Q. If frequency is increased to 100 Hz, reactance becomes _____ ohms

2.5

None

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

unity power factor

low efficiency

high power factor

maximum load current

None

. In a pure inductive circuit

the current can lead or lag by 90°

the current is in phase with the voltage

the current lags behind the voltage by 90°

the current leads the voltage by 90°

None

The period of a wave is

time required to complete one cycle

the same as frequency

expressed in amperes

None

The phase difference between voltage and current wave through a circuit element is given as 30°. The essential condition is that

both waves must have identical peak values

both waves must have same frequency

both waves must have zero value at the same time

None

. If two sinusoids of the same frequency but of different amplitudes and phase angles are subtracted, the resultant is

a sinusoid of half the original frequency

a sinusoid of the same frequency

not a sinusoid

a sinusoid of double the frequency

None

Power factor of an inductive circuit is usually improved by connecting capacitor to it in

series

parallel

either series or paralle

None

A heater is rated as 230 V, 10 kW, A.C. The value 230 V refers to

r.m.s. voltage

peak voltage

average voltage

None

The r.m.s. value of a sinusoidal A.C. current is equal to its value at an angle of______degrees

None

If a sinusoidal wave has frequency of 50 Hz with 30 A r.m.s. current which of the following equation represents this wave ?

30 sin 50 t

60 sin 25 t

42.42 sin 314t

84.84 sin 25 t

None

Form factor for a sine wave is

0.707

1.11

0.637

1.414

None

The square waveform of current has following relation between r.m.s. value and average value

r.m.s. value of current is less than average value

r.m.s. value of current is greater than average value

r.m.s. value is equal to average value

None

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

zero

minimum

maximum

infinity

None

All the rules and laws of D.C. circuit also apply to A.C. circuit containing

capacitance only

resistance only

inductance only

None

Form Factor is the ratio of

r.m.s. value/average value

average value/r.m.s. value

r.m.s. value/peak value

average value/peak value

None

Capacitors for power factor correction are rated in

kVA

kVAR

None

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

both will reach their maximum values at the same instant

both will reach their minimum values at the same instant

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

None

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