^Photocell

Also called electric eye works on the photoelectric effect. Its electrical properties are affected by the amount of light.

It can be used as light meters to measure the intensity of light in scientific work. In the reproduction of sound in motion pictures and in the television camera for scanning and telecasting, as burglar alarm, as fire alarm, as automatic door, opener, in electronic ignition circuits, as automatic counter to count the no. persons entering an auditorium.