Final answer:
The Compton effect causes the wavelength of the scattered photon to be longer than that of the incident photon due to inelastic scattering, a phenomenon first explained by Arthur Compton.
Step-by-step explanation:
In the Compton effect, the wavelength of the scattered photon is longer than the wavelength of the incident photon. Compton scattering is an example of inelastic scattering, where the scattered radiation possesses a longer wavelength due to the energy and momentum transferred to the target electron during the collision. The Compton shift signifies the difference between the incident and scattered radiation's wavelengths and depends on factors like the scattering angle. This phenomenon can't be explained by classical physics and instead relies on the quantum perspective, treating photons as particles with momenta.
The Compton effect was first explained by Arthur H. Compton, who demonstrated that X-rays, when scattered off materials such as graphite, emerge with a different wavelength compared to the incident X-rays due to energy transfer to electrons. Compton's theory adhered to the principles of conservation of linear momentum and conservation of total relativistic energy, leading to a new understanding of light behavior at the quantum level.