# Electrical power

Description of how to calculate electrical power

## Definition of electical power

Electrical power in a circuit is the energy that is absorbed or generated in the circuit. The symbol for electric power is$$P$$.

The electrical power is calculated from the voltage multiplied by the current. The unit of measurement of electrical power is the Watt $$W$$.

The dependency can be defined as

$$\displaystyle Power=Voltage · Current$$       $$\displaystyle P=U · I$$

By definition, the power P = 1W, if the voltage U = 1V (Volt) and the current 1A (Amper).

$$1W=1V·1A$$

With Ohm's law $$U = I · R$$ , the formula for the electric power can be changed as follows

$$\displaystyle P=(I·R)·I=I^2·R$$
$$\displaystyle P=U·\frac{U}{R}=\frac{U^2}{R}$$