Alternating Current RLC Circuit MCQ [Free PDF] - Objective Question Answer for Alternating Current RLC Circuit Quiz

11. In an inductive circuit, the voltage_______ the current?

A. Leads
B. Lags
C. Is greater than
D. Is less than

Answer: A

In a pure inductive circuit, the voltage leads the current and the current lags the voltage by a phase difference of 90 degrees.

12. In an inductive circuit, the current________ the voltage?

A. Leads
B. Lags
C. Is greater than
D. Is less than

Answer: B

In a pure inductive circuit, the voltage leads the current, and the current lags the voltage by a phase difference of 90 degrees.

13. In which device inductor cannot be used?

A. filter circuit
B. transformer
C. choke
D. dielectric

Answer: D

Inductor has a wide number of applications.

It is used in LR filter circuits, transformers, and choke coils.

14. A resistance of 7 ohms is connected in series with an inductance of 31.8mH. The circuit is connected to a 100V 50Hz sinusoidal supply. Calculate the current in the circuit.

A. 2.2A
B. 4.2A
C. 6.2A
D. 8.2A

Answer: D

X_L = 2 × π × f × L = 10 ohm.

Impedance is given by

Z² = (R²+X_L²)

Therefore the total impedance Z = 12.2ohm.

V = IZ

∴ I = V/Z

= 100/12.2 = 8.2A.

15. A resistance of 7 ohms is connected in series with an inductance of 31.8mH. The circuit is connected to a 100V 50Hz sinusoidal supply. Calculate the phase difference.

A. -55.1
B. 55.1
C. 66.1
D. -66.1

Answer: A

The phase angle of the Inductive circuit is given as

φ = tan^-1(XL/R) = 55.1

Since this is an inductive circuit, the current will lag, hence φ = -55.1.

16. A resistance of 7 ohms is connected in series with an inductance of 31.8mH. The circuit is connected to a 100V 50Hz sinusoidal supply. Calculate the voltage across the resistor.

A. 31.8V
B. 57.4V
C. 67.3V
D. 78.2V

Answer: B

X_L = 2 × π × f × L = 10 ohm.

Z² = (R²+X_L²)

Therefore, the total impedance Z = 12.2ohm.

V = IZ

∴I = V/Z = 100/12.2 = 8.2A.

Voltage across resistor = 8.2 × 7 = 57.4V.

17. A resistance of 7 ohms is connected in series with an inductance of 31.8mH. The circuit is connected to a 100V 50Hz sinusoidal supply. Calculate the voltage across the inductor.

A. 52V
B. 82V
C. 65V
D. 76V

Answer: B

X_L = 2 × π × f × L = 10 ohm. Z² = (R²+X_L²)

Therefore, the total impedance Z = 12.2ohm.

V = IZ

∴ I = V/Z = 100/12.2 = 8.2A.

Voltage across inductor = 8.2 × 10 = 82V.

18. A resistance of 7 ohms is connected in series with an inductance of 31.8mH. The circuit is connected to an x V 50Hz sinusoidal supply. The current in the circuit is 8.2A. Calculate the value of x.

A. 10V
B. 50V
C. 100V
D. 120V

Answer: C

X_L = 2 × π × f × L = 10 ohm. Z² = (R²+X_L²)

Therefore, the total impedance Z = 12.2ohm.

V = IZ

∴ V = 12.2 × 8.2 = 100V.

19. Which, among the following, is the correct expression for φ.

A. φ = tan^-1 (XL/R)
B. φ = tan^-1 (R/XL)
C. φ = tan^-1 (XL × R)
D. φ = cos^-1 (XL/R)

Answer: A

From the impedance triangle, we get

tanφ = XL/R.

Hence φ = tan^-1 (XL/R).

20. For an RL circuit, the phase angle is always ________

A. Positive
B. Negative
C. 0
D. 90

Answer: B

For a series resistance and inductance circuit, the phase angle is always a negative value because the current will always lag the voltage.

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