Device for measuring or detecting electromagnetic radiation (e.g. light) through variations of conductivity when exposed to light.

A metallic substance, used in electrophotographic printers, that conducts and retains electrical charges until they are exposed to light.

This is a part of a copier that receives the image of the original on its surface. It can accept and hold an applied charge and have that charge dissipated with the addition of light.

A radiation sensitive resistor whose resistance decreases as it is exposed to radiant energy.