**Power**= V I

= Voltage * Current

*Units*are Watts (

**W**)

This equation can be combined with Ohms Law to give an expression for the power dissipated in a resistor as:

**Power = I2 R**

=

*(Current through Resistor)2 * Resistance*

*Unit*s are Watts (

**W**)

This is derived as follows:

Power = VI

V = I R (from Ohms Law)

Combining these gives Power = I I R

or Power = I2R