**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 D*q* moves through the resistor in a time D*t*,
the power loss is

where * I* is the current through the resistor and

The formula * P = I V* also gives the power generated by a battery
if