What is the electrons velocity that made its momentum equal to the momentum of photon whose wave length 5200A?
mass of the electron m = 9.11 x 10^-31
Planck's constant h = 6.626 x 10^-34
wavelength w = 5200 x 10^-10
plug in the values:
particle momentum = mv
photon momentum = h/w
mv = h/w
v = h/wm