CET AC Circuit Analysis & Power 2

Question 1

In a series RLC circuit at resonance, which statement is TRUE?

Accepted Answer

Inductive and capacitive reactances are equal and cancel

Answer

Impedance is at its maximum value

Answer

Current is at its minimum value

Answer

Power factor equals zero

Question 2

What is the phase relationship between voltage and current in a purely capacitive AC circuit?

Accepted Answer

Current leads voltage by 90°

Answer

Voltage leads current by 90°

Answer

Voltage and current are in phase

Answer

Current lags voltage by 45°

Question 3

A circuit has a true power of 300 W and an apparent power of 500 VA. What is the reactive power?

Accepted Answer

400 VAR

Answer

200 VAR

Answer

800 VAR

Answer

150 VAR

Question 4

Which instrument is used to measure the phase angle between voltage and current in an AC circuit?

Accepted Answer

Power factor meter

Answer

Wattmeter

Answer

Ammeter

Answer

Frequency counter

Question 5

What happens to the capacitive reactance (XC) of a capacitor if the frequency of the applied AC signal is doubled?

Accepted Answer

XC is halved

Answer

XC doubles

Answer

XC quadruples

Answer

XC remains unchanged

Question 6

In an AC circuit, what does the Q factor (quality factor) of a resonant circuit indicate?

Accepted Answer

The bandwidth relative to the resonant frequency

Answer

The ratio of reactive power to true power

Answer

The power factor of the circuit

Answer

The ratio of resistance to reactance

Question 7

What is the impedance of a series circuit containing a 40 Ω resistor, XL = 80 Ω, and XC = 50 Ω?

Accepted Answer

50 Ω

Answer

170 Ω

Answer

90 Ω

Answer

60 Ω