Black light is the colloquial term for ultraviolet radiation (UV radiation for short) and here specifically for the range of UV-A radiation. UV radiation is an electromagnetic radiation. Since it lies outside the light spectrum of 400 to 700 nm visible to humans, we cannot perceive it.
For example, with a so-called low-pressure gas discharge lamp (similar to the fluorescent lamp), the so-called black light tube – or with the help of ultraviolet light-emitting diodes – the black light
LED. It is mainly used in
discotheques or for
show effects. Its effect only unfolds in darkened rooms. The radiation stimulates
neon colors and other
fluorescent substances to glow (for example, the optical brighteners often used in many detergents).