Question

In a Compton scattering experiment, the incident X-rays have a wavelength of 0.2686 nm, and the scattered X-rays have a wavelength of 0.2705 nm. Through what angle in the drawing are the X-rays scattered?

E, Photon scattering from stationary electron

Answer 1

using the equation

lambda' - lambda = h*(1 - cos theta)/(mc)

lambda' = 0.2705*10^-9 m

lambda = 0.2686*10^-9 m

1 - cos theta = (mc/h)*(lambda' - lambda)

cos theta = 1 - (mc/h)*(lambda' - lambda)

m = electron rest mass = 9.1*10^-31 kg

cos theta = 1 - (9.1*10^-31*3*10^8/(6.634*10^-34)*(0.2705 - 0.2686)*10^-9)

cos theta = 1 - 0.78188 = 0.21812

theta = arccos (0.21812) = 77.40 deg