Greetings @munawar1235,

You have explained it very cleary

Waves below 400 nanometers are called ultraviolet waves and more low wavelength rays include X-rays and cosmic rays.

Based on the wavelengths of ultraviolet radiation with biological materials, three divisions have been designated:
UVA (400–315 nm), also called blacklight;
UVB (315–280 nm), responsible for the radiation's best-known effects on organisms
UVC (280–100 nm), which does not reach Earth's surface.

Thank you for sharing