ISCET AC Circuits and Analysis Questions and Answers

Question 1

In a series RLC circuit, what is the condition known as resonance?

Accepted Answer

The total impedance is equal to the resistance.

Answer

The inductive reactance is greater than the capacitive reactance.

Answer

The capacitive reactance is greater than the inductive reactance.

Answer

The phase angle between voltage and current is 90 degrees.

Question 2

A technician is analyzing an AC circuit and notes that the current waveform leads the voltage waveform. Which of the following best describes the load?

Accepted Answer

Primarily capacitive

Answer

Purely resistive

Answer

Primarily inductive

Answer

The load is at resonance.

Question 3

What is the primary purpose of improving the power factor in an AC circuit, ideally towards unity (1.0)?

Accepted Answer

To reduce the total current drawn from the source for the same amount of real power.

Answer

To increase the circuit's resonant frequency.

Answer

To decrease the apparent power consumed by the load.

Answer

To maximize the phase angle between voltage and current.

Question 4

A series AC circuit consists of a 30 Ω resistor and a capacitor with a capacitive reactance (XC) of 40 Ω. What is the total impedance (Z) of this circuit?

Accepted Answer

50 Ω

Answer

70 Ω

Answer

10 Ω

Answer

1200 Ω

Question 5

Which of the following will cause the resonant frequency of a series LC circuit to decrease?

Accepted Answer

Increasing the capacitance.

Answer

Decreasing the inductance.

Answer

Increasing the source voltage.

Answer

Adding a resistor in series.

Question 6

A technician measures an AC motor load and finds the real power is 1200 W and the apparent power is 1500 VA. What is the power factor of this load?

Accepted Answer

0.8 lagging

Answer

1.25 leading

Answer

1.0 (unity)

Answer

0.9 lagging