>>213032781Fun fact, the photon doesn't bounce off a mirror (or anything). Its absorbed and another photon is re-emitted by the electron shell of an atom, less a tiny cost of energy.
If you've ever seen solid gold, it has that really incredible luster because the electron shell of gold is mostly empty, so it happily takes in and shoots out electrons and photons, which is what makes it such a good conductor.
Its also neat to know that gold's particular luster is caused by a quantum effect that has to do with the energy gained and lost when a photon hits a gold atom.