## 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 = V*and_{m}sin (wt + 30°)*i = I*. The power factor angle of the circuit is_{m}sin (wt − 45°)

- 15°
- 75°
- 45
^{o} - 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 *v _{1} = 100 sin (ωt + 30°)* and

*v*. The phasor relationship between the voltages can be expressed as

_{2}= 200 sin (ωt − 60°)*v*lags_{1}*v*by 90°_{2}*v*lags_{2}*v*by 90°_{1}*v*lags_{1}*v*by 30°_{2}*v*lags_{2}*v*by 60°_{1}

**Answer:** *v _{2}* lags

*v*by 90°

_{1}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
- X
_{L}= X_{C} - R = L = C

**Answer:** X_{L} = X_{C}

22. Two impedances *Z _{1} = 4 + j4 Ω* and

*Z*are connected in parallel. Their equivalent impedance is

_{2}= 4 − j4 Ω- 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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