PEC Electrical Theory & Principles

Question 1

What is Ohm's Law?

Accepted Answer

V = I × R.

Answer

Ohm's Law is a fundamental principle in electrical engineering that describes the relationship between voltage (V), current (I), and resistance (R) in an electrical circuit. The formula V = I × R states that the voltage across a conductor is directly proportional to the current flowing through it, with the constant of proportionality being the resistance. This law is essential for analyzing and designing electrical systems.

Question 2

What is the unit of electrical power?

Accepted Answer

Watts.

Answer

Watts (W) are the standard unit of measurement for electrical power, which quantifies the rate at which electrical energy is transferred or consumed. Power is calculated as the product of voltage and current (P = V × I). Understanding wattage is crucial for sizing electrical components and assessing energy consumption in various devices and systems.

Question 3

What is the difference between alternating current (AC) and direct current (DC)?

Accepted Answer

AC flows in one direction; DC flows in one direction.

Answer

Alternating Current (AC) is characterized by its periodic reversal of direction, meaning the current flow changes back and forth. In contrast, Direct Current (DC) flows consistently in a single direction. This fundamental difference in current behavior dictates how electricity is generated, transmitted, and used in various applications, from household outlets (AC) to batteries (DC).

Question 4

What does a fuse do in an electrical circuit?

Accepted Answer

It protects the circuit by breaking the connection when the current is too high.

Answer

A fuse is a critical safety device in an electrical circuit designed to protect against overcurrent. It contains a thin wire that melts and breaks the circuit connection if the current exceeds a safe level. This interruption prevents damage to electrical components and wiring, significantly reducing the risk of overheating and electrical fires.

Question 5

What is the primary function of a transformer in an electrical circuit?

Accepted Answer

To change the voltage level of alternating current (AC).

Answer

The primary function of a transformer is to change the voltage level of alternating current (AC) in an electrical circuit. It can either step up (increase) or step down (decrease) voltage without significantly changing the frequency. This capability is crucial for efficient power transmission over long distances and for adapting voltage to suit various electrical devices.

(PC) Professional Electrical Contractor Practice Test

(PC) Professional Electrical Contractor Practice Test

PEC Electrical Theory & Principles