Energy dissipation in resistors

As a charge q moves through a resistor, it loses a potential energy qV where V is the potential drop across the resistor. This energy goes into heat, much like the way a ball of putty that falls off a cliff converts its potential energy to heat when it hits the ground. We refer to this conversion of potential energy into heat as dissipation.

The power dissipated in a resistor is the energy dissipated per time. If an amount of charge Dq moves through the resistor in a time Dt, the power loss is

where I is the current through the resistor. This relation P=IV is correct for any component. For instance, in a battery the power generated by the battery is also IV where I and V are the current through and voltage across of the battery.

Examples     Resistor's index