Electric power

Definition

Electric power is the rate at which electrical energy is transferred by an electric circuit. It is typically measured in watts (W), where 1 watt equals 1 joule per second.

5 Must Know Facts For Your Next Test

1. Electric power can be calculated using the formula $P = IV$, where $P$ is power, $I$ is current, and $V$ is voltage.
2. The unit of electric power is the watt (W), named after James Watt.
3. $P = I^2 R$ and $P = \frac{V^2}{R}$ are alternative formulas for calculating power when resistance ($R$) is known.
4. In alternating current (AC) circuits, real power (measured in watts) differs from apparent power (measured in volt-amperes, VA).
5. Power loss in transmission lines can be minimized using high voltage to reduce current.

Review Questions

• What formula would you use to calculate electric power if you know the current and voltage?
• How does increasing resistance affect the power dissipated in a circuit?
• Why is high voltage used in power transmission to minimize losses?

Related terms

Current:

The flow of electric charge through a conductor, typically measured in amperes (A).

Voltage:

The electric potential difference between two points, measured in volts (V).

Resistance:

A measure of the opposition to the flow of current in an electrical circuit, measured in ohms ($\Omega$).