A combination of batteries is called a cell.

A positive charge $q$ is released at a point $P$. It moves towards a nearby point $Q$. The potential at $Q$ is lower than that at $P$.

If $W$ is the work done in moving a charge $Q$ from a point $A$ to another point $B$. The potential difference $V_B-V_A$ is given by,

$V_B-V_A=\frac{W}{Q}$

Also, if a charge $Q$ flows through a conductor, an electric current is said to exist in the conductor and its magnitude is given by,

$I=\frac{Q}{t}$; where $\text{'}t\text{'}$ is the time for which charge $Q$ flows through the conductor.

Calculate the potential difference between the two terminals of a battery if $100 \mathrm{J}$ of work is required to transfer $20 \mathrm{C}$ from one terminal of the battery to the other.