18.3 Compton Effect

18.3 Compton Effect

Arthur Holly Compton at Washington university in 1923 studied the scattering of X-rays by loosely bound electrons from a graphite target (Fig. 18.5). He measured the wavelength of X-rays scattered at an angle $\theta$ with the original direction. He found that wavelength $\lambda'$, of the scattered X-rays is larger than the wavelength $\lambda_{o}$ of the incident X-rays. This is known as Compton effect. The increase in wavelength of scattered X-rays could not be explained on the basis of classical wave theory. In order to explain this effect, Compton suggested that X-rays consist of photons with energy $hc / \lambda$ and momentum $h/\lambda$.

(Fig. 18.5: Compton's scattering experiment)