The conduction electrons in a metal could be approximated as free particles, which ane described by the fermi statistics. in order for the conduction electrons to escape at the surface of a metal, they need to overcome a potential energy barrier of height δ at the surface, an elect ron will escape only if its component of velocity normal to the surface as 'm exceeds calculate the current density of the electrons emitted from the surface, you may assume (a-7) > > kt where μ is the chemical potential