Watt's Law (P=IV)

Watt's Law states that the amount of electric power (in watts) through a circuit is equivalent to the the product of the current traveling through the circuit (in amps) and the voltage (in volts).

Electric power is the rate at which electric energy is transferred through an electric circuit

For example, a simple circuit with a 9 volt battery as the power source and a current flow of 10 amps has a power output of 90 Watts.

In mathematical form this law can be written as

$P=IV$

Where $P$ is the power in Watts, $I$ is the current in Amps, and $V$ is the voltage in Volts.