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 lightLED
. 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).