Kilowatt-hours

Definition

A kilowatt-hour (kWh) is a unit of energy equivalent to the power consumption of one kilowatt over one hour. It is commonly used by electric utilities to measure energy usage.

5 Must Know Facts For Your Next Test

1. 1 kWh equals 3.6 million joules (J).
2. Electric bills use kWh to quantify energy consumption.
3. Power (in watts) multiplied by time (in hours) gives you energy in kWh.
4. $E = P \times t$ where $E$ is energy in kWh, $P$ is power in kilowatts, and $t$ is time in hours.
5. 1 kW equals 1000 watts; therefore, if a device uses 1000 watts for one hour, it consumes 1 kWh.

Review Questions

Related terms

Joule:

A unit of energy in the International System of Units (SI), equal to the work done when applying a force of one newton over a distance of one meter.

Watt:

A unit of power in the International System of Units (SI), equal to one joule per second.

Power:

The rate at which work is done or energy is transferred over time, measured in watts (W).