Important MCQs of AC Circuit
In this post, some of the mcqs of ac circuits are given. It includes amplitude factor, important of dielectric insulation, peak factor, crest factor, unit of angular velocity, hot wire voltage, RMS value of half wave rectifier, form factor for half wave, average value of half wave, DC ammeter reads, RMS value of semicircle voltage and power factor of pure resistive circuit.
AC Circuit MCQ: 41 to 45
41 The amplitude factor for the sinusoidal waveform is
( a )√ 3
( b )√ 2
( c )1.11
( d )0.78
Correct Answer ( b ): √ 2
42 Which of the following is important for dielectric insulation testing?
( a )Form factor
( b )Peak factor
( c )RMS value
( d )Average value
Correct Answer ( b ): Peak factor
The dielectric stress which insulation subject to directly proportional to maximum or peak value of applied voltage therefore knowledge of peak factor is important for dielectric insulation testing.
43 The peak factor is also known as
( a )Crest factor
( b )Form factor
( c )Power factor
( d )Maximum factor
Correct Answer ( a ): Crest factor
Peak factor is also known as crest factor or amplitude factor.
44 The RMS voltage for voltage V = 50 sin 314t is
( a )50 × √ 2 V
( b )50 V
( c )50 / √ 2
( d )Zero volt
Correct Answer ( c ): 50 / √ 2
Compare V = 50 sin 314t with V = Vm Sin ωt
Here, Vm = 50 V therefore VRMS = 50 / √ 2
45 The frequency for voltage waveform V = 50 sin 314t is
( a )314 Hz
( b )100 Hz
( c )50 Hz
( d )Zero
Correct Answer ( c ): 50 Hz
Compare V = 50 sin 314t with V = Vm Sin 2πft
2πf = 314 therefore f = 50 Hz
AC Circuit MCQ: 46 to 50
46 The unit of angular velocity is
( a )Radian
( b )Radian / second
( c )Degree
( d )Radian – second
Correct Answer ( b ): Radian / second
47 Which of the following relation is true?
( a )f = 2πω
( b )ω = πf
( c )ω = 2πf
( d )ω = 2π / f
Correct Answer ( c ): ω = 2πf
48 The angular velocity for voltage waveform V = 100 sin 314t is
( a )50 radian / second
( b )314 radian / second
( c )3.14 radian / second
( d )Zero
Correct Answer ( b ): 314 radian / second
Compare V = 100 Sin 314t with V = Vm Sin ωt
Therefore, angular velocity ω = 314 radian per second
49 The time period for voltage waveform V = 100 sin 314t is
( a )0.04 second
( b )0.02 second
( c )0.01 second
( d )0.1 second
Correct Answer ( b ): 0.02 second
Compare V = 100 Sin 314t with V = Vm Sin ωt
Here ω = 100
2πf = 100 therefore f = 50 Hz
Time period T = 1/f = 1/50 = 0.02 second
50 The frequency for voltage waveform V = 100 sin 314t is
( a )314 Hz
( b )100 Hz
( c )50 Hz
( d )Zero Hz
Correct Answer ( c ): 50 Hz
AC Circuit MCQ: 51 to 55
51 The hot wire voltmeter always reads
( a )Peak voltage
( b )Average voltage
( c )RMS voltage
( d )None of the above
Correct Answer ( c ): RMS voltage
The hot wire volt meter always read RMS voltage.
More Detail About Hot Wire Voltmeter
52 The RMS value of half wave rectifier alternating voltage is
( a )Vm / √2
( b )Vm
( c )Vm / 2
( d )√ 2Vm
Correct Answer ( c ): Vm / 2
The alternating voltage is taken for 0 to π period for half wave rectifier,
53 The average value of half wave rectifier alternating voltage is
( a )Imax / 2
( b )Imax/ √ 2
( c )Imax / π
( d )Imax / √ 3
Correct Answer ( c ): Imax / π
54 The value of form factor for half wave alternating quantity is
( a )0.707
( b )1.11
( c )1.57
( d )1.68
Correct Answer ( c ): 1.57
Form factor = RMS Current / Average Current
= (Im/2) / ( Im/π) = π/2
55 The moving coil ammeter always reads
( a )Maximum current
( b )Average current
( c )RMS current
( d )None of the above
Correct Answer ( b ): Average current
The moving coil ammeter always reads average current for whole cycle
AC Circuit MCQ: 56 to 60
56 The DC ammeter always read _____ value of rectifier current.
( a )Maximum
( b )Average
( c )RMS
( d )Zero
Correct Answer ( b ): Average
The AC ammeter reads RMS current whereas DC ammeter reads average current of rectified current.
57 The RMS value of semicircle voltage waveform with radius of b is equal to
( a )√ ( 2b )
( b )√ 2 × ( b )
( c )√ ( 2b2 / 7 )
( d )√ ( 2b2 / 3 )
Correct Answer ( d ): √ ( 2b2 / 3 )
58 The angle between the voltage vector and current vector in the pure resistive circuit is
( a )45o
( b )90o
( c ) 135o
( d ) 0o
Correct Answer ( d ): 0o
The angle between voltage vector and current vector in the pure resistive circuit is zero
59 Which of the following is not equation of power loss in the pure resistive circuit?
( a )VI
( b )V2/ R
( c )I2R
( d )V2R
Correct Answer ( d ): V2R
The equation of power loss = I2R = V2R = VI
60 The power factor of pure resistive circuit is
( a ) 0o
( b ) 90oLagging
( c ) 90oLeading
( d )Unity
Correct Answer ( d ): Unity
The angle between voltage vector and current vector in the pure resistive circuit is zero therefore
Cos 0o = 1
AC Circuit MCQ PDF
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