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).


With Ohm's law \(U = I ยท R\) , the formula for the electric power can be changed as follows

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