Question

explain why the photoelectric effect is so important to quantum mechanics?

Answer 1

The effect is one of the proofs that the light is a particle.

Answer 2

please explain it

Answer 3

A light particle or photon has energy depends on its frequency. when photon hits the metal surface, if its energy enough to remove an electron from surface of the metal it transfers all the energy to the electron. In other words, the photon becomes localized and give all energy to the electron. If its energy is not enough, nothing happen.

If the light has only wave property, while the light intensity goes up, electron energy also goes up. But this does not happen. This causes only that number of the electrons go up.