Question

To recharge a 12 v battery, a battery charger must move 3.3 × 105 c of charge from the negative terminal to the positive terminal. how much work is done by the battery charger? answer in units of j

Answer 1

Work done is calculated by change * potential difference 
in equation it means: W = Q * V 

since the 2 terminals have now dq charge and (V) potential difference 

small work done (dW) = V dq 
total work done W = V Q = 12 * 3.3*10^5 = 3.96 *10^6 Joules which is approximately 4 mega joules