hi i was thinking about the photoelectric effect, that we discussed in school: we said that, when a photon enters, it has an energy and this energy is used for electron binding energy and kinetic energy. so far so good. but how is it possible, that the electron is emitted in the opposite direction of the incoming photon? this is totally against my understanding of conservation of momentum? at first, i thought that it might be possible, that the metal layer itself would absorb twice the amount of momentum in the direction of the incoming photon. but this is also impossible, as this would need a huge amount of energy too, so there could not be any emitted electrons with the full kinetic energy. therefore, my question is: where am i wrong?