Compton Scattering Caculator
λ= Initial wavelength of the photon before scattering; λ' = Final wavelength of the photon after scattering; θ = Scattering angle; h= Plank's constant ; me = Rest mass of an electron; c = speed of light in vaccum
When a photon hits an electron (or any quasi-free charged particle), the wavelength of the photon increases due to the energy loss of the photon. This is an inelastic scattering since the energy (so as the wavelength) of the scattered particle got changed. This is called "Compton Scattering."