A sensor circuit produces an output p.d. that changes as a result of a physical variable such as temperature or light intensity.A potential divider consists of two or more resistors in series and a source of fixed potential difference.If a potential divider consists of a fixed resistors in series with a thermistor the potential difference of the source is divided between the two resistors.This type of potential divider could be used to supply a temperature dependent p.d. less than the source p.d.