A light sensor circuit produces an output p.d. that changes as a result of a change in 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 light dependent resistor (LDR) the potential difference of the source is divided between the two resistors.This type of potential divider could be used to supply a p.d. less than the source p.d. which is dependent on light intensity