Light Gate Ipc. For use as light operated timing gate. Comprises photodetector and light source each housed in robust ABS case spaced 40mm apart on plastic rod. Light source housing has battery compartment and on/off switch. Photodetector housing is fitted with pair of 4mm sockets to allow connection to electronic timers. When the timing gate is switched on it creates short circuit between the two output sockets, this then becomes an open circuit each time the light beam is interrupted. Consequently the timing gate can be used as remote switching device in wide range of dynamics experiments.