Objective Questions on Steady-State Analysis
Objective Questions on Steady-State Analysis of AC Circuits, MCQ on Steady-State Analysis of AC Circuits, Objective Questions on steady-state analysis of R-L, R-C, R-L-C series network, Multiple Choice Questions (MCQ) on R-L, R-C and R-L-C circuits.
Multiple Choice Questions on AC circuit analysis
- The voltage and current in an AC circuit is represented by u = Vm sin (wt + 30°) and i = Im sin (wt − 45°). The power factor angle of the circuit is
- 15°
- 75°
- 45o
- 30°
Answer: 75°
2. A current is represented by i = 100 sin (314t − 30°) A. The rms value of the current and the frequency are, respectively
- 100 A and 314 Hz
- 100 A and 50 Hz
- 70.7 A and 314 Hz
- 707 A and 50 Hz
Answer: 707 A and 50 Hz
3. A current of 10 A is flowing through a circuit. The power factor is 0.5 lagging. The instantaneous value of the current can be written as
- i = 10 sin 60° A
- i = 10 sin (ωt − 30°) A
- i = 14.14 sin (ωt − 60°) A
- i = 14.14 sin (ωt + 60°) A
Answer: i = 14.14 sin (ωt − 60°) A
4. In a purely inductive circuit
- current lags the voltage by 90°
- current leads the voltage by 90°
- voltage lags the current by 90°
- current lags the voltage by 180°
Answer: current lags the voltage by 90°
5. Form factor of an AC wave indicates
- Low sharp or steep the wave shape is
- Low flat the wave shape is
- Low symmetrical the wave shape is
- The degree of its conformity to sinusoidal form
Answer: Low sharp or steep the wave shape is
6. Power consumed by a pure inductor is
- infinite
- very high
- zero
- very small
Answer: zero
7. If form factor of a sinusoidal wave is 1.11, then the form factor of a triangular wave will
- also be 1.11
- be less than 1.11
- be more than 1.11
- be 1
Answer: be more than 1.11
8. A voltage of v = 100 sin (314t − 30°) is connected across a 10-Ω resistor. The power dissipated in the circuit will be
- 100000 W
- 1000 W
- 500 W
- 250 W
Answer: 500 W
9. The average value of a sinusoidal current is
- \frac{2I_{m}}{\pi}
- \frac{I_{m}}{\pi}
- \frac{I_{m}}{2\pi}
- \frac{I_{m}^{2}}{2\pi}
Answer: \frac{2I_{m}}{\pi}
10. Form factor of an alternating wave form is the ratio of
- rms value and average value
- Average value and rms value
- Maximum value and average value
- Maximum value and rms value
Answer: rms value and average value
11. A capacitance of C farad is connected to a 230V, 50 Hz supply. The value of capacitive reactance is
- 314 C \Omega
- \frac{1}{314 C} \Omega
- 628 C \Omega
- \frac{1}{628 C} \Omega
Answer: \frac{1}{314 C} \Omega
12. The form factor of a square wave is
- 1.11
- 1.0
- 0
- 1.414
Answer: 1.0
13. Two sinusoidal waves are represented as v1 = 100 sin (ωt + 30°) and v2 = 200 sin (ωt − 60°). The phasor relationship between the voltages can be expressed as
- v1 lags v2 by 90°
- v2 lags v1 by 90°
- v1 lags v2 by 30°
- v2 lags v1 by 60°
Answer: v2 lags v1 by 90°
14. Inductive reactance of coil of 0.1 H at 50 Hz is
- 31.4 Ω
- 62.8 Ω
- 314 Ω
- 5 Ω
Answer: 31.4 Ω
15. The power factor of a purely resistive circuit is
- 1.0
- 0
- 0.1
- 0.5
Answer: 1.0
16. A series RLC circuit has R = 50 Ω, L = 50 μH and C = 2 μF. The Q-factor of the circuit is
- 0.1
- 1
- 10
- 2
Answer: 0.1
17. When a parallel circuit is in resonance, which of the following of the circuit is maximum?
- current
- impedance
- admittance
- power factor
Answer: impedance
18. In a series resonant circuit, a change in supply voltage will cause a change in
- the current drawn,
- the Q-factor of the circuit,
- the bandwidth of the circuit,
- the resonant frequency as well
Answer: the current drawn
19. Which of the following conditions is true for both series and parallel resonance?
- impedance is minimum
- power factor is unity
- power factor is zero
- power is low
Answer: power factor is unity
20. The product of voltage and current in an AC circuit is called
- active power
- apparent power
- average power
- reactive power
Answer: apparent power
21.In a series resonance circuit
- L = C
- L = R
- XL = XC
- R = L = C
Answer: XL = XC
22. Two impedances Z1 = 4 + j4 Ω and Z2 = 4 − j4 Ω are connected in parallel. Their equivalent impedance is
- 8 + j8 Ω
- 4 + j0 Ω
- 8 − j8 Ω
- 8 + j0 Ω
Answer: 4 + j0 Ω
23.When an inductance L and a resistance R are connected in parallel across an AC supply, the current drawn by the two parallel branches will be out of phase by
- 0°
- 90°
- 180°
- 45°
Answer: 90°
24. The resonant frequency in R-L-C series circuit is
- f_{0}=\frac{2\pi }{\sqrt{LC}}
- f_{0}=\frac{\sqrt{LC} }{2\pi }
- f_{0}=\frac{1 }{2\pi \sqrt{LC}}
- f_{0}=\frac{1}{2\pi }\sqrt{\frac{L }{C}}
Answer: f_{0}=\frac{1 }{2\pi \sqrt{LC}}
25. The bandwidth of a series R-L-C circuit is
- \frac{C}{2\pi L}
- \frac{R}{2\pi L}
- \frac{C}{2\pi R}
- \frac{L}{2\pi R}
Answer: \frac{R}{2\pi L}
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