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Question 15: In a Compton scattering experiment, an electron is accelerated straight in the direction of incident x-ray photon. Which way does the scattered photon move?


Compton shift in wavelength is given by

As the electron accelerates straight ahead in the direction of photon, therefore, the collision between them is head on. Therefore, the photon will either rebound back or go along the electron. Thus the angle of scattering of photon will be either 180° or 0°.

If we are interested in the wavelength of the scattered photon, then if the photon is rebounded θ = 180° and hence,

(Since cos180° = -1)

If the photon goes along the electron, θ = 0° and,

(Since cos 0 = 0)


Hence there would be no shift in the wavelength of the photon.


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