Potential difference (or voltage) is a measure of energy, per unit of charge, transferred between two points in a circuit. A potential difference of 1 volt means that 1 joule of work is done per ...

Learn how electric circuits work and how to measure current and potential difference with this guide for KS3 physics students aged 11-14 from BBC Bitesize.

The starting point is the price information for each date on which you're producing an average. First, calculate the difference between the two prices for each date.