Ultraviolet radiation has wavelengths between 400nm and 15nm, falling between violet light and X-rays on the electromagnetic spectrum. It is divided into UV-A from 400-320nm, UV-B from 320-280nm, and UV-C from 280-100nm, with shorter wavelengths being more energetic and potentially dangerous. UV-A passes through glass while UV-B induces vitamin D production but can cause harm from overexposure.

1. Ultraviolet Radiation
Alex Norton

2. On the Electromagnetic Spectrum
Ultraviolet
Wavelength between 400nm, that of violet light and 15nm,
that of X rays.
Ultraviolet literally means “beyond violet”.

3. Types
Name Wavelength / nm Energy per photon / ev
UV-A 400 - 320 3.10 - 3.94
UV-B 320 - 280 3.94 - 4.43
UV-C 280 - 100 4.43 - 12.4
Generally speaking, the shorter the wavelength, the
more dangerous the radiation is.

4. UV-A
Passes through ordinary glass.
Makes up for 98.7% of the ultraviolet radiation that
reaches the Earth’s surface.

5. UV-B
Positives
Induces vitamin D production.
Negatives
Overexposure