<Dl> <Dd> λ = h p (\ displaystyle \ lambda = (\ frac (h) (p))) </Dd> </Dl> <Dd> λ = h p (\ displaystyle \ lambda = (\ frac (h) (p))) </Dd> <P> This is a generalization of Einstein's equation above, since the momentum of a photon is given by p = E c (\ displaystyle (\ tfrac (E) (c))) and the wavelength (in a vacuum) by λ = c f (\ displaystyle (\ tfrac (c) (f))), where c is the speed of light in vacuum . </P> <P> De Broglie's formula was confirmed three years later for electrons (which differ from photons in having a rest mass) with the observation of electron diffraction in two independent experiments . At the University of Aberdeen, George Paget Thomson passed a beam of electrons through a thin metal film and observed the predicted interference patterns . At Bell Labs, Clinton Joseph Davisson and Lester Halbert Germer guided their beam through a crystalline grid . </P>

The radiation is a wave not a particle