A?proton?is a subatomic particle, symbol p or p+, with a positive electric charge of +1e elementary charge and mass slightly less than that of a neutron.?Protons?and neutrons, each with masses of approximately one atomic mass unit, are collectively referred to as nucleons.

In a photon-particle collision (such as photon-electron collision) the quantity which is not conserved is number of photons

The?de Broglie wavelength?is the?wavelength, ?, associated with a massive particle and is related to its momentum, p, through the Planck constant, h: ? = h p .

Davisson Germer experiment proves that electrons exhibit wave nature