Question

Consider fig. for photoemission. How would you recocile with momentum-conservation? Note light (photons) have momentum in a different direction than the emitted electrons.

Answer 1

During photoelectric emission, the momentum of incident photon is transfered to the metal. At microscopic level, atoms of a metal absorb the photon and its momentum is transfered mainly to the nucleus and electrons. The electron excited is emitted. Therefore, the conservation of momentum is to be considerd as the momentum of incident photon transfered to the nucleus and electrons.