Photocell (noun)

An electrical device that generates a current when exposed to light.

Origin:

Derived from the greek words 'photos' meaning 'light' and 'cell' meaning 'a small room', photocell refers to an electrical device that generates a current when exposed to light.

Examples:

1. Photocells are commonly used in street lights to turn them on and off automatically.
2. A photocell is the key component of a solar panel, converting light energy into electrical energy.
3. Photocells are used in burglar alarms to detect any sudden changes in light levels.
4. Photocells are used in many scientific experiments to measure the intensity of light.
5. A photocell can be used to regulate the speed of an electric motor in response to changes in light levels.