What is the electrons velocity that made its momentum equal to the momentum of photon whose wave length 5200A?

Answer 1

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