A phenomenon called Compton scattering was discovered in 1924 by A. H. Compton. When X-rays strike matter, some of the radiation is scattered on the electrons of light atoms. Compton discovered that some of the scattered radiation has longer wavelength than does the incident radiation, and that the change in wavelength depends on the angle at which the radiation is scattered. Compton scattering is explained by the notion of photons of energy hν and momentum hν/c where h = 6.63?10-34 J s is Planck's constant, and ν is the photon's frequency. The notion of Compton scattering can be reduced to collisions between the photons and the electrons that are almost entirely random. The conservation of energy and momentum is given by the following equation: Δλ = λ' - λ = h/mc(1 - cosΘ) = K(1 - cosΘ) Where λ is the wavelength of the incident radiation, λ' is the wavelength of the scattered radiation, m is the mass of electron, c is the speed of light, and Θ is an angle of scattering. The quantity K = h/mc = 0.002426 nm is known as the Compton wavelength. In the spectrum of scattered radiation, there is also a shorter-wavelength peak at the same wavelength λ' as that for the incident X-rays, along with the longer-wavelength peak of the wavelength λ. It corresponds to the X-ray scattering from the tightly bound electrons. The relationship between the intensities of the peaks depends on the material that is being used. Compton scattering is on of the most striking confirmations of the quantum theory.