# Electric Power

## Key Questions

• First of all, kilowatt-hour od kilowatt hour has many symbols: kW·h, kW h or kWh. It is a unit of energy equal to 1,000 watt-hours, or 3.6 megajoules.

Very simple:
If the energy is being transmitted or used at a constant power over a period of time, the total energy in kilowatt-hours is the product of the power in kilowatts and the time in hours.

It is commonly used as a billing unit for energy delivered to consumers by electric utilities.

Power is the rate of doing work.

#### Explanation:

Energy is power $\times$ time.

The electrical unit of power- watts or kilowatts

For energy - kilowatts hours.

• We know that electric power dissipated as a result of Joule's effect is given by,

$P = {I}^{2} R t$, thus in order to minimize the power loss, the current is supplied under very high voltage and as a consequence of law of conservation of energy, the current is reduced and substantially heat loss is also reduced.