Electrical Engineering - RC Circuits

Exercise :: RC Circuits - General Questions

16. 

A resistor and a capacitor are in series across a 20 V ac source. Circuit impedance is 4.33 k. Current flow in the circuit is

A. 9.2 mA
B. 92 mA
C. 4.6 mA
D. 460 mA

Answer: Option C

Explanation:

No answer description available for this question. Let us discuss.

17. 

For a certain load, the true power is 150 W and the reactive power is 125 VAR. The apparent power is

A. 19.52 W
B. 195.2 W
C. 275 W
D. 25 W

Answer: Option B

Explanation:

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18. 

When the frequency of the voltage applied to a series RC circuit is increased, the phase angle

A. increases
B. decreases
C. remains the same
D. becomes erratic

Answer: Option B

Explanation:

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19. 

In a series RC circuit, when the frequency and the resistance are halved, the impedance

A. doubles
B. is halved
C. is reduced to one-fourth
D. cannot be determined without values

Answer: Option D

Explanation:

No answer description available for this question. Let us discuss.

20. 

A 2 k resistor is in series with a 0.015 F capacitor across a 15 kHz ac source. What is the magnitude of the total impedance and the phase angle?

A. 73.4 and θ = –19.5°
B. 707 and θ = –19.5°
C. 2121 and θ = –19.5°
D. 734 and θ = –38.9°

Answer: Option C

Explanation:

Xc = 1/2πfC = 707 Ω

Z = R - jXc = 2000 - j(707)

|z| = sqrt(R*R + Xc*Xc) = 2121 Ω

Phase angle = arctangent(Xc/R) = 19.5°