NETA AC/DC Theory and Circuits 2

Question 1

In a series RLC circuit at resonance, which of the following is true?

Accepted Answer

Inductive and capacitive reactances are equal and cancel

Answer

At resonance in a series RLC circuit, XL equals XC, so they cancel and the impedance equals only the resistance R, making it minimum. Current is therefore at its maximum.

Question 2

Ohm's law states that current in a circuit is:

Accepted Answer

Directly proportional to voltage and inversely proportional to resistance

Answer

Ohm's law: I = V/R. Current is directly proportional to voltage and inversely proportional to resistance.

Question 3

The time constant of an RC circuit is defined as:

Accepted Answer

The time for the capacitor voltage to reach 63.2% of the applied voltage

Answer

The RC time constant t = RC is the time for the capacitor to charge to approximately 63.2% (1 - 1/e) of the source voltage.

Question 4

In a purely inductive AC circuit, the current:

Accepted Answer

Lags the voltage by 90 degrees

Answer

In a purely inductive circuit, voltage leads current (or current lags voltage) by 90 degrees due to the inductor's property of opposing changes in current.

Question 5

The effective (RMS) value of a sinusoidal AC voltage is approximately what fraction of the peak voltage?

Accepted Answer

0.707 times the peak voltage

Answer

The RMS value of a sine wave is Vpeak divided by the square root of 2, approximately 0.707 times Vpeak. This is the value that produces the equivalent heating effect as a DC voltage.

(NETA) InterNational Electrical Testing Association Certified Technicians Practice Test

(NETA) InterNational Electrical Testing Association Certified Technicians Practice Test

NETA AC/DC Theory and Circuits 2