IST Electrical and Electronic Knowledge 2

Question 1

What does AC stand for in electrical systems?

Accepted Answer

Alternating Current

Answer

AC stands for Alternating Current, which periodically reverses direction, unlike Direct Current (DC).

Question 2

What is the standard frequency of AC power in the United States?

Accepted Answer

60 Hz

Answer

The US power grid operates at 60 Hz, meaning the current alternates direction 60 times per second.

Question 3

What is the function of a transformer in an electrical system?

Accepted Answer

Change voltage levels from one level to another

Answer

Transformers step AC voltage up or down to different levels using electromagnetic induction.

Question 4

A motor nameplate shows 480V/3-phase. What does '3-phase' indicate?

Accepted Answer

The motor uses three separate AC waveforms offset by 120 degrees

Answer

Three-phase power uses three AC waveforms that are each offset by 120 degrees, providing more efficient power delivery for industrial motors.

Question 5

If two 10-Ohm resistors are connected in parallel, what is the total resistance?

Accepted Answer

5 Ohms

Answer

For two equal resistors in parallel, total resistance = R/2 = 10/2 = 5 Ohms.

IST - Industrial Skills Test Practice Test