For ten points, what effect named for an American physicist is usually important only for gamma and X-rays?
It is strong evidence for quantum theory because an explanation requires one to treat light as photons rather than as waves. Conservation of momentum and energy requires that when a photon collides with a stationary electron, it loses energy.  For ten points, what effect named for an American physicist is usually important only for gamma and X-rays?
It is strong evidence for quantum theory because an explanation requires one to treat light as photons rather than as waves.
Compton effect (don't accept inverse Compton)