In a series RLC circuit, during resonance

Inductive reactance becomes equal to capacitive reactance

Only capacitive reactance becomes zero

Only inductive reactance becomes zero

Assertion(A): When a series RLC circuit is in resonance, the current flowing in the circuit is maximumReason(R): The inductive reactance and the capacitive reactance are equal in magnitude at resonance.

Both A and R are true but R is NOT the correct explanation of A

Both A and R are true and R is the correct explanation of A

Both A and R are true but R is NOT the correct explanation of A

Directions: It consists of two statements, one labelled as the ‘Statement (I)’ and the other as ‘Statement (II)’. Examine these two statements carefully and select the answers to these items using the codes given below:Statement (I):During resonance, an R-L-C series circuit behaves like a purely resistive circuit.Statement (II):During resonance in an R-L-C series circuit, the voltages across the L- and the C-elements are in phase to each other.

Statement (I) is false but Statement (II) is true

Both Statement (I) and Statement (II) are individually true and Statement (II) is the correct explanation of Statement (I)

Both Statement (I) and Statement (II) are individually true but Statement (II) is not the correct explanation of Statement (I)

Statement (I) is true but Statement (II) is false

Statement (I) is false but Statement (II) is true

In a series resonant circuit, maximum voltage across L occurs at

At a frequency where I is maximum

Slightly below resonant frequency

Slightly above resonant frequency

At a frequency where I is maximum

In an R-L-C series circuit, at resonance frequency, the voltage across the resistance is:

Much higher than the applied voltage

Much lower than the applied voltage

Much higher than the applied voltage

A function of the value of the inductance

Directions: Each of the next items consists of two statements, one labeled as the `Assertion (A)' and the other as 'Reason (R)' You are to examine these two statements carefully and select the answers to these items using the codes given below :Assertion (A): The power factor of an inductor is zero.Reason (R): The voltage Across and current through the inductor are in quadrature.

Both A and R are individually true but R is not the correct explanation of A

Both A and R are individually true and R is the correct explanation of A

Both A and R are individually true but R is not the correct explanation of A

In RLC circuits, the current at resonance is

maximum in parallel circuit and minimum in series circuit

maximum is series RLC and minimum in parallel RLC circuit

maximum in parallel circuit and minimum in series circuit

Assertion (A): Q factor of a series resonant circuit is \(\frac{1}{R}\sqrt \frac{L}{C}\)Reason (R): High Q means better selectivity

Both (A) and (R) are true and (R) is the correct explanation of (A)

Both (A) and (R) are true, but (R) is not the correct explanation of (A)

For a parallel RLC resonant circuit with resistance in series with inductor, what will be the effect on resonant frequency, if we increase the value resistance?

Resonant frequency will increase

Resonant frequency will decrease

114 + Mcqs in Resonance in Electrical Engineering Page 2 McqOptions

51.	In a RLC circuit Inductance is 20 mH and capacitance is 200 micro Farad. Find the resonance frequency of the circuit.
A.	1000 rad/sec
B.	250 rad/sec
C.	500 rad/sec
D.	50 rad/sec
Answer» D. 50 rad/sec

Discussion

52.	In a series RLC circuit, during resonance
A.	Inductive reactance becomes equal to capacitive reactance
B.	Only R becomes zero
C.	Only capacitive reactance becomes zero
D.	Only inductive reactance becomes zero
Answer» B. Only R becomes zero

Discussion

53.	A series RLC circuit has a bandwidth of 300 rad/sec at a resonant frequency of 3000 rad/sec when excited by a voltage source of 100 V. The inductance of the coil is 0.1 H. The value of R and the voltage across C are, respectively
A.	10 Ω and 100 V
B.	30 Ω and 100 V
C.	30 Ω and 1000 V
D.	300 Ω and 1000 V
Answer» D. 300 Ω and 1000 V

Discussion

54.	Q factor of a series RLC circuit with R = 10 Ω, L = 25 mH, C = 100 μF is
A.	0.0395
B.	100.71
C.	1.58
D.	1.58 × 10-3
Answer» D. 1.58 × 10-3

Discussion

55.	For a series RLC circuit, R = 10 Ω, inductive reactance XL = 20 Ω and capacitive reactance XC = 20 Ω. If the applied voltage is 100 V AC, then current in the circuit is:
A.	5 A
B.	10 A
C.	20 A
D.	0 A
Answer» C. 20 A

Discussion

56.	A half-wave, controlled rectifier with a purely resistive load has delay \(\alpha =\frac{\pi}{3}\), Calculate form factor.
A.	1.5
B.	1.9
C.	2.03
D.	4.2
Answer» D. 4.2

Discussion

57.	For what value of RC will V and I be in phase?
A.	12 Ω
B.	6 Ω
C.	3 Ω
D.	9 Ω
Answer» D. 9 Ω

Discussion

58.	In an series RLC circuit, R = 1 kΩ , L = 10 μH, C = 1 μF and source voltage = 10 V. The current in the circuit at resonance is
A.	10 mA
B.	100 mA
C.	20 mA
D.	1 mA
Answer» B. 100 mA

Discussion

59.	An inductive circuit of resistance 2 ohms and inductance 0.5 H is connected to a 250 volts, 50 Hz supply. What capacitance will be placed in parallel to produce resonance?
A.	50 micro-farad
B.	20.2 micro-farad
C.	70 micro-farad
D.	74 micro-farad
Answer» C. 70 micro-farad

Discussion

60.	A series L - C - R circuit has a resonant frequency f0 with R = 1 Ω, L = 1 H and C = 1 F. If the components values are tripled, the new resonant frequency will be:
A.	3 f0
B.	unaltered
C.	\(\frac{f_0}{\sqrt{3}}\)
D.	\(\frac{f_0}{3}\)
Answer» E.

Discussion

61.	An R-L-C series resonant circuit has the following parameters: Resonance frequency = 5000 / 2π Hz; impedance at resonance = 56 Ω and Q-factor = 25. Calculate the capacitance of the capacitor.
A.	143 μF
B.	0.143 μF
C.	1.43 μF
D.	14.3 μF
Answer» C. 1.43 μF

Discussion

62.	A coil of resistance 20 Ω and inductance 10 mH is in series with a capacitance and is supplied with a constant voltage, variable frequency source. The maximum current is 2 A at 1000 Hz. The Q-factor of the circuit is _______.
A.	31.8
B.	3.14
C.	314
D.	31.4
Answer» C. 314

Discussion

63.	In an RLC series order circuit, R = 5 Ω, C = 100 μF and L is a variable. A voltage of 100 V is applied to a circuit at an angular frequency of 1000 rad/s. L changes so much that the voltage at R is maximized. What will be the required value of L?
A.	0.01 H
B.	10 H
C.	0.1 H
D.	1 H
Answer» B. 10 H

Discussion

64.	Considering the following statements P and QP: At the resonant frequency the impedance of series RLC circuit is zero.Q: In parallel GLC circuit, increasing the conductance G results in increase in its Q-factor.Which of the following is correct
A.	P is false and Q is true
B.	Both P and Q are true
C.	P is true and Q is false
D.	Both P and Q are false
Answer» E.

Discussion

65.	Determine the value of inductor (in mH) connected in parallel with a capacitance of 5 F having a quality factor 6. Assume the resonant frequency of 5 rad /s.
A.	8
B.	7
C.	9
D.	8.5
Answer» B. 7

Discussion

66.	A series resonant circuit has a resistance of 1 kΩ and half-power frequencies of 10 and 90 kHz, then the bandwidth and resonant frequency of the circuit, respectively, are:
A.	9 kHz and 40 kHz
B.	80 kHz and 30 kHz
C.	40 kHz and 10 kHz
D.	80 kHz and 9 kHz
Answer» C. 40 kHz and 10 kHz

Discussion

67.	A series RLC circuit has R = 50 Ω, L = 100 μH and C = 1μF. The lower half power frequency of the circuit is
A.	30.55 kHz
B.	51.92 kHz
C.	3.055 kHz
D.	1.92 kHz
Answer» D. 1.92 kHz

Discussion

68.	Calculate the quality factor of the resonant series RLC circuit, if its bandwidth is 30 Hz. (Resonant frequency = 1 Hz)
A.	30
B.	15
C.	2/30
D.	1/30
Answer» E.

Discussion

69.	Assertion(A): When a series RLC circuit is in resonance, the current flowing in the circuit is maximumReason(R): The inductive reactance and the capacitive reactance are equal in magnitude at resonance.
A.	Both A and R are true and R is the correct explanation of A
B.	Both A and R are true but R is NOT the correct explanation of A
C.	A is true but R is false
D.	A is false but R is true
Answer» B. Both A and R are true but R is NOT the correct explanation of A

Discussion

70.	A series RLC circuit supplied by 220 V ac voltage has R = 10 Ω, L = 10 mH and C = 1 μF. Find the quality factor of inductor at resonance?
A.	10
B.	100
C.	20
D.	50
Answer» B. 100

Discussion

71.	A tuned amplifier has a maximum output at 4 MHz with a quality factor 50. The bandwidth and half power frequencies are respectively
A.	80 kHz and 4.04 MHz; 3.96 MHz
B.	80 kHz and 4.08 MHz; 3.92 MHz
C.	40 kHz and 4.04 MHz; 3.96 MHz
D.	40 kHz and 4.08 MHz; 3.92 MHz
Answer» B. 80 kHz and 4.08 MHz; 3.92 MHz

Discussion

72.	In the circuit shown below, readings of the voltmeter are V1 = 100 V, V2 = 50 V, V3 = 50 V. What will be the source voltage?
A.	100 V
B.	200√2 V
C.	100√2 V
D.	200 V
Answer» B. 200√2 V

Discussion

73.	Directions: It consists of two statements, one labelled as the ‘Statement (I)’ and the other as ‘Statement (II)’. Examine these two statements carefully and select the answers to these items using the codes given below:Statement (I):During resonance, an R-L-C series circuit behaves like a purely resistive circuit.Statement (II):During resonance in an R-L-C series circuit, the voltages across the L- and the C-elements are in phase to each other.
A.	Both Statement (I) and Statement (II) are individually true and Statement (II) is the correct explanation of Statement (I)
B.	Both Statement (I) and Statement (II) are individually true but Statement (II) is not the correct explanation of Statement (I)
C.	Statement (I) is true but Statement (II) is false
D.	Statement (I) is false but Statement (II) is true
Answer» D. Statement (I) is false but Statement (II) is true

Discussion

74.	In a series resonant circuit, maximum voltage across L occurs at
A.	Resonant frequency
B.	Slightly below resonant frequency
C.	Slightly above resonant frequency
D.	At a frequency where I is maximum
Answer» D. At a frequency where I is maximum

Discussion

75.	In an R-L-C series circuit, at resonance frequency, the voltage across the resistance is:
A.	Much lower than the applied voltage
B.	Equal to the applied voltage
C.	Much higher than the applied voltage
D.	A function of the value of the inductance
Answer» C. Much higher than the applied voltage

Discussion

76.	Consider the following statements associated with resonant frequency:(a) For a series RLC circuit, the current is maximum(b) For a series RLC circuit, the voltage across C is minimum(c) For a series RLC circuit, the current is minimum(d) For a parallel RLC circuit, the total impedance is maximumWhich one of the above statements is/are correct?
A.	(a), (b) and (d) only
B.	(b) and (d) only
C.	(a) and (d) only
D.	(a) and (b) only
Answer» D. (a) and (b) only

Discussion

77.	Directions: Each of the next items consists of two statements, one labeled as the `Assertion (A)' and the other as 'Reason (R)' You are to examine these two statements carefully and select the answers to these items using the codes given below :Assertion (A): The power factor of an inductor is zero.Reason (R): The voltage Across and current through the inductor are in quadrature.
A.	Both A and R are individually true and R is the correct explanation of A
B.	Both A and R are individually true but R is not the correct explanation of A
C.	A is true but R is false
D.	A is false but R is true
Answer» B. Both A and R are individually true but R is not the correct explanation of A

Discussion

78.	A tuned amplifier has center frequency of 3 MHz and required bandwidth for speech is 5 kHz. The Q factor of amplifier will be ______.
A.	0.0166
B.	600
C.	15 × 109
D.	300
Answer» C. 15 × 109

Discussion

79.	Determine the quality factor of a series resonant RLC circuit, when the bandwidth of the circuit is 20 Hz.(Resonant frequency = 1 Hz)
A.	0.08
B.	0.05
C.	0.04
D.	0.02
Answer» C. 0.04

Discussion

80.	In RLC circuits, the current at resonance is
A.	maximum is series RLC and minimum in parallel RLC circuit
B.	maximum in parallel circuit and minimum in series circuit
C.	maximum in both circuits
D.	minimum in both circuits
Answer» B. maximum in parallel circuit and minimum in series circuit

Discussion

81.	For a series resonant circuit, what happens to the Q-factor when the capacitance of the circuit is increased three times and the frequency is slashed by four times?
A.	It remains unchanged
B.	It decreases by half
C.	It doubles
D.	It increases to 1.33 times
Answer» E.

Discussion

82.	Assertion (A): Q factor of a series resonant circuit is \(\frac{1}{R}\sqrt \frac{L}{C}\)Reason (R): High Q means better selectivity
A.	Both (A) and (R) are true and (R) is the correct explanation of (A)
B.	Both (A) and (R) are true, but (R) is not the correct explanation of (A)
C.	(A) is true, but (R) is false
D.	(A) is false, but (R) is true
Answer» C. (A) is true, but (R) is false

Discussion

83.	In a series R-L-C circuit, magnitude of resonance frequency can be changed by changing the value of
A.	R only
B.	L only
C.	C only
D.	L or C
Answer» E.

Discussion

84.	For the A.C circuit as shown below, if the rms voltage across the resistor is 120V. What is the value of the inductor?
A.	0.5 H
B.	0.6 H
C.	1.0 H
D.	1.5 H
Answer» E.

Discussion

85.	For a parallel RLC resonant circuit with resistance in series with inductor, what will be the effect on resonant frequency, if we increase the value resistance?
A.	Resonant frequency will increase
B.	Resonant frequency will decrease
C.	Effect cannot be estimated
D.	Resonant frequency will remain
Answer» C. Effect cannot be estimated

Discussion

86.	Consider the following statements with respect to a parallel R-L-C circuit:1. The bandwidth of the circuit decreases if R is increased.2. The bandwidth of the circuit remains the same if L is increased.3. At resonance, the input impedance is a real quantity.4. At resonance, the magnitude of the input impedance attains its minimum value.Which of the above statements are correct?
A.	1, 2 and 4
B.	1, 3 and 4
C.	2, 3 and 4
D.	1, 2 and 3
Answer» E.

Discussion

87.	In a series R-L-C circuit supplied by a source of 125 V at a resonant frequency of 220 Hz, the magnitudes of the voltages across the capacitor and the inductor are found to be 4150 V. If the resistance of the circuit is 1 Ω, then the selectivity of the circuit is
A.	33.20
B.	3.32
C.	0.0301
D.	0.301
Answer» B. 3.32

Discussion

88.	A series RLC circuit has ωo = 105, Q = 50, R = 400 Ω. The value of C is:
A.	250 pF
B.	1000 pF
C.	500 pF
D.	1.25 pF
Answer» D. 1.25 pF

Discussion

89.	An RLC series circuit is said to be inductive if
A.	ωL > 1/ωC
B.	ωL = 1/ωC
C.	ωL < 1/ωC
D.	ωL = ωC
Answer» B. ωL = 1/ωC

Discussion

90.	Find the value of Q if the reactive power is 10W and the average power is 5W.
A.	10
B.	5
C.	2
D.	1
Answer» D. 1

Discussion

91.	Find the reactive power when the average power is 5W and Q=2.
A.	10W
B.	5W
C.	2W
D.	1W
Answer» B. 5W

Discussion

92.	At bandwidth frequency range, the value of the voltage V is?
A.	V=Vm/2
B.	V=Vm2
C.	V=Vm
D.	V=Vm/√2
Answer» E.

Discussion

93.	What happens to the voltage across the inductor when the Q factor decreases?
A.	Increases
B.	Decreases
C.	Remains the same
D.	Becomes zero
Answer» C. Remains the same

Discussion

94.	What happens to the voltage across the capacitor when the Q factor increases?
A.	Increases
B.	Decreases
C.	Remains the same
D.	Becomes zero
Answer» B. Decreases

Discussion

95.	Find the source voltage when the voltage across the inductor is 2000V and the Q factor is 20.
A.	10V
B.	200V
C.	100V
D.	90V
Answer» D. 90V

Discussion

96.	Find the Q factor when the voltage across the inductor is 2000V and the source voltage is 100V.
A.	10
B.	20
C.	30
D.	40
Answer» C. 30

Discussion

97.	What is the voltage across the inductor when the source voltage is 200V and the Q factor is 10?
A.	100V
B.	20V
C.	2000V
D.	0V
Answer» D. 0V

Discussion

98.	In a series RLC circuit, the phase difference between the voltage across the capacitor and the voltage across the inductor is?
A.	0
B.	900
C.	1800
D.	3600
Answer» D. 3600

Discussion

99.	In a series RLC circuit, the phase difference between the voltage across the capacitor and the current in the circuit is?
A.	0
B.	900
C.	1800
D.	3600
Answer» C. 1800

Discussion

100.	In a series RLC circuit, the phase difference between the voltage across the inductor and the current in the circuit is?
A.	0
B.	900
C.	1800
D.	3600
Answer» C. 1800

Discussion

Explore topic-wise MCQs in Electrical Engineering.

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In a series resonant circuit, maximum voltage across L occurs at

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In a series R-L-C circuit, magnitude of resonance frequency can be changed by changing the value of

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