Potential Difference

Potential difference (p.d.) is defined as the work done per unit charge:

$V = \frac{W}{Q}$

where $W$ is the energy transferred (J) and $Q$ is the charge (C).

Potential difference is measured using a voltmeter connected in parallel across the component.

The total p.d. across components in series equals the supply voltage (Kirchhoff’s second law). The p.d. across components in parallel is the same for each branch.