Simple Circuit Modules.These modules may be used to construct simple circuits of the type normally implemented on for example a Worcester Circuit Board. They are intended to introduce younger pupils (ages 11-13) to some of the more familiar applications of devices and circuits the main emphasis being on simple electrical circuit work.The modules are 60 x 60mm and have 4mm plug connections.This is a ORP13 4mm light dependent resistor.In normal conditions resistance is 220 Ohm approximately.Fully covered resistance is 40 K ohm approximately.