a
Electromagnetic radiation is classified into types according to the frequency of the wave. These types include, in order of increasing frequency, radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, \(X\)-rays and gamma rays.

The frequency is the inverse of wavelength. Hence, in the order of increasing wavelength, the waves are Gamma rays ( \( < 1\, nm )\), X-rays \(( 1 - 1 0 ~ n m )\), infra red rays \(\left(700-10^5\, nm \right)\), micro waves \(\left(10^5-10^8 \,nm \right)\), radio waves \(\left( > 10^8\,nm \right)\).