ExamAdept

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: C

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°

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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: D

No answer description is available. Let's discuss.

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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: B

No answer description is available. Let's discuss.

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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: B

No answer description is available. Let's discuss.

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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: C

No answer description is available. Let's discuss.

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Questions for: Rc Circuits