Question

How photoelectric effect works when photon don't have mas?

Answer 1

The photoelectric effect works like this. If you shine light of high enough energy on to a metal, electrons will be emitted from the metal. ... A photonwith an energy less than the workfunction will never be able to eject electrons. Before Einstein's explanation, the photoelectric effectwas a real mystery.

Answer 2

One way to think of mass is as nothing more than a convenient name for rest energy. Photons are indeed massless and thus have zero rest energy. This is not an issue because according to special relativity, they do not come with a rest frame.

Please note that assuming we denote rest mass by mm, the well-known E=mc2 is not the whole story - the general formula reads

E2=m2c4+p2c2

In principle, you could think of three types of particles, depending on the relative values of energy and momentum:

E2>p2E2>p2: massive particles, v<c

E2=p2E2=p2: massless particles (eg photons), v=c

E2<p2E2<p2: tachyonic 'particles', v>c

The last variant is hypothetical and not really particle-like (they cannot be properly localized and would manifest more like an action-at-a-distance).

hope this helps you....