ISCET AC Circuits and Analysis 2

Question 1

In a series RLC circuit at resonance, what happens to the impedance?

Accepted Answer

Impedance equals the resistance R

Answer

At resonance, XL and XC cancel, leaving only the resistive component R as the total impedance.

Question 2

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

Accepted Answer

Current leads voltage by 90°

Answer

In a purely capacitive circuit, current leads the voltage by 90 degrees.

Question 3

If the frequency of an AC signal doubles, what happens to the capacitive reactance (XC)?

Accepted Answer

XC halves

Answer

Since XC = 1/(2πfC), doubling frequency halves the capacitive reactance.

Question 4

The power factor of an AC circuit is defined as:

Accepted Answer

True power divided by apparent power

Answer

Power factor equals true (real) power divided by apparent power, or equivalently cos(θ).

Question 5

A transformer has a primary winding of 200 turns and a secondary winding of 50 turns. If 120V AC is applied to the primary, what is the secondary voltage?

Accepted Answer

30V

Answer

Using the turns ratio: Vs = Vp × (Ns/Np) = 120 × (50/200) = 30V.

(ISCET) International Society of Certified Electronics Technicians Practice Test

(ISCET) International Society of Certified Electronics Technicians Practice Test

ISCET AC Circuits and Analysis 2