In 1801, German physicists discovered is a section outside the purple end of the daylight spectrum. It could sensitize photographic films containing silver bromide.
And thus discovered the presence of ultraviolet rays. But at that time there was no concept of electromagnetic waves,
The scientific community did not reach any agreement on the nature of light. It was not until the wonderful Maxwell equations were summarized.
To put forward that people gradually realized the series of invisible rays. Such as ultraviolet rays and others that the eyes can’t see are essentially electromagnetic waves.
Now that we know ultraviolet light is an electromagnetic wave with a wavelength between 10nm and 400nm.
As its wavelength is just outside the visible light of the human eye. We call it ultraviolet light, in English, also commonly known as UV.
https://tank007.comproduct-category/uv-flashlight/
