AC Circuit Analysis MCQs

Practice AC Circuit Analysis MCQs with four options, answers and explanations for focused Electronics & Telecommunication Engineering revision.

Question 1

Network TheoryAC Circuit Analysis

In a purely capacitive AC circuit, current ideally?

ALags voltage by 90 degrees
BLeads voltage by 90 degrees
CIs in phase with voltage
DLeads voltage by 180 degrees

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Correct Answer: B. Leads voltage by 90 degrees

Explanation: For an ideal capacitor, current leads voltage by 90 degrees.

Reference: Standard network theory: ac circuit analysis

Question 2

Network TheoryAC Circuit Analysis

The impedance of an ideal inductor in sinusoidal steady state is?

A1/(j omega L)
Bj omega L
CR+jL
Dj/(omega L)

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Correct Answer: B. j omega L

Explanation: An ideal inductor has impedance ZL = j omega L.

Reference: Standard network theory: ac circuit analysis

Question 3

Network TheoryAC Circuit Analysis

The impedance of an ideal capacitor in sinusoidal steady state is?

Aj omega C
B1/(j omega C)
Cj/C
Domega/C

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Correct Answer: B. 1/(j omega C)

Explanation: An ideal capacitor has impedance ZC = 1/(j omega C), equivalent to -j/(omega C).

Reference: Standard network theory: ac circuit analysis

Question 4

Network TheoryAC Circuit Analysis

At 50 Hz, the inductive reactance of a 0.1 H inductor is closest to?

A3.14 ohm
B31.4 ohm
C50 ohm
D314 ohm

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Correct Answer: B. 31.4 ohm

Explanation: XL = 2πfL = 2π×50×0.1 ≈ 31.4 ohm.

Reference: Standard network theory: ac circuit analysis

Question 5

Network TheoryAC Circuit Analysis

At 50 Hz, the capacitive reactance magnitude of a 100 microfarad capacitor is closest to?

A3.18 ohm
B31.8 ohm
C100 ohm
D318 ohm

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Correct Answer: B. 31.8 ohm

Explanation: XC = 1/(2πfC) = 1/(2π×50×100×10^-6) ≈ 31.8 ohm.

Reference: Standard network theory: ac circuit analysis

Question 6

Network TheoryAC Circuit Analysis

A series circuit has R = 3 ohm and inductive reactance XL = 4 ohm. The magnitude of its impedance is?

A1 ohm
B5 ohm
C7 ohm
D12 ohm

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Correct Answer: B. 5 ohm

Explanation: For Z = R+jXL, |Z| = sqrt(R^2+XL^2) = sqrt(9+16) = 5 ohm.

Reference: Standard network theory: ac circuit analysis

Question 7

Network TheoryAC Circuit Analysis

A series circuit has R = 6 ohm, XL = 8 ohm and negligible capacitive reactance. If supplied by 100 V RMS, the current magnitude is?

A5 A
B10 A
C12.5 A
D16.67 A

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Correct Answer: B. 10 A

Explanation: |Z| = sqrt(6^2+8^2) = 10 ohm, so I = 100/10 = 10 A.

Reference: Standard network theory: ac circuit analysis

Question 8

Network TheoryAC Circuit Analysis

Admittance is defined as?

AThe reciprocal of impedance
BThe square of impedance
CResistance plus reactance only
DVoltage divided by power

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Correct Answer: A. The reciprocal of impedance

Explanation: Admittance Y = 1/Z and is measured in siemens.

Reference: Standard network theory: ac circuit analysis

Question 9

Network TheoryAC Circuit Analysis

The reciprocal of resistance is called?

AReactance
BConductance
CSusceptance
DInductance

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Correct Answer: B. Conductance

Explanation: Conductance G = 1/R and is measured in siemens.

Reference: Standard network theory: ac circuit analysis

Question 10

Network TheoryAC Circuit Analysis

In a purely inductive AC circuit, current ideally?

ALeads voltage by 90 degrees
BLags voltage by 90 degrees
CIs in phase with voltage
DLags voltage by 180 degrees

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Correct Answer: B. Lags voltage by 90 degrees

Explanation: For an ideal inductor, voltage leads current by 90 degrees; equivalently, current lags voltage by 90 degrees.

Reference: Standard network theory: ac circuit analysis

Question 11

Network TheoryAC Circuit Analysis

A coil has resistance 6 ohm and inductive reactance 8 ohm. Its impedance angle is closest to?

A36.9 degrees
B53.1 degrees
C60 degrees
D90 degrees

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Correct Answer: B. 53.1 degrees

Explanation: The impedance angle is tan^-1(XL/R)=tan^-1(8/6)≈53.1 degrees.

Reference: Standard network theory: impedance angle

Question 12

Network TheoryAC Circuit Analysis

A sinusoidal voltage has RMS value 230 V. Its peak value is approximately?

A162.6 V
B230 V
C325.3 V
D460 V

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Correct Answer: C. 325.3 V

Explanation: For a sinusoid, Vpeak=sqrt(2)Vrms≈1.414×230=325.3 V.

Reference: Standard network theory: RMS to peak numerical

Question 13

Network TheoryAC Circuit Analysis

A sinusoidal current has peak value 10 A. Its RMS value is approximately?

A5 A
B7.07 A
C10 A
D14.14 A

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Correct Answer: B. 7.07 A

Explanation: For a sine wave, Irms=Ipeak/sqrt(2)=10/1.414≈7.07 A.

Reference: Standard network theory: peak to RMS numerical

Question 14

Network TheoryAC Circuit Analysis

The average value of a pure sinusoidal voltage over one complete cycle is?

AIts RMS value
BIts peak value
CZero
DPeak divided by two

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Correct Answer: C. Zero

Explanation: Positive and negative half-cycle areas cancel, so the average over a full cycle is zero.

Reference: Standard network theory: sinusoidal average value

Question 15

Network TheoryAC Circuit Analysis

For an impedance Z=3-j4 ohm, the magnitude of Z is?

A1 ohm
B5 ohm
C7 ohm
D25 ohm

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Correct Answer: B. 5 ohm

Explanation: |Z|=sqrt(3^2+(-4)^2)=5 ohm.

Reference: Standard network theory: complex impedance numerical

Question 16

Network TheoryAC Circuit Analysis

For Z=3-j4 ohm, the impedance angle is closest to?

A-53.1 degrees
B+53.1 degrees
C-36.9 degrees
D+36.9 degrees

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Correct Answer: A. -53.1 degrees

Explanation: The angle is tan^-1(-4/3)≈-53.1 degrees, indicating capacitive behavior.

Reference: Standard network theory: impedance phase numerical

Question 17

Network TheoryAC Circuit Analysis

An admittance is Y=0.04+j0.03 S. Its magnitude is?

A0.01 S
B0.05 S
C0.07 S
D0.12 S

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Correct Answer: B. 0.05 S

Explanation: |Y|=sqrt(0.04^2+0.03^2)=0.05 S.

Reference: Standard network theory: admittance magnitude numerical