The electric power used by the car battery is given by
[tex]P=VI[/tex]
where
V is the voltage of the battety
I is the current
P is the electric power.
For the battery in our problem, the voltage is V=12.0 V while the current intensity is I=0.5 A, so the power used by the battery is
[tex]P=VI=(12.0 V)(0.5 A)=6.0 W[/tex]
