A potential divider consists of two or more resistors in series and a source of fixed potential difference.If a potential divider consists of one fixed resistor in series with a variable resistor, the potential difference of the source is divided between the two resistors.This type of potential divider could be used to supply a variable p.d. less than the source p.d.
ratio of p.d.s = ratio of resistors
| V1 V2 | = | R1 R2 |