1)How can I find the wavelength as a function of the kinetic energy i)for photons, ii)for electrons? i)For photons. I think that I found it. I used the relation: E^2=c^2*p^2+(mc^2)^2 The photon's rest mass is 0. So we get: E=c*p p=E/c ---> p=h*v/c --->p=h/λ Finally: λ=c*h/E ii)For electrons. I don't know what to do. Do I have to use the same equations?