Potential difference: The potential difference between two points in an electric field is the amount of work done in bringing a unit positive charge from one point to the other.
In Fig. $A$ and $B$ are two points located in the electric field of a charge $Q$ placed at origin $O$.
If $W$ work is done in bringing a charge $\mathrm{Q}_0$ from $B$ to $A$, then potential difference between $A$ and $B$ is
$V=\frac{W}{Q_0} \text { or Potential difference }=\frac{\text { Work done }}{\text { Charge }}$
The SI unit of potential difference is joule/coulomb or volt.
