Question

what happening to a photon,which strikes a metal and ejects an electron?

Answer 1

The energy of a photon is based on it's frequency per:
\[E=hf\]
The higher the frequency, the more energy the photon has and can impart to an electron upon contact to raise it from ground state and eject it from the atom. There is a threshold that must be achieved, in frequency, which much be reached to observe the effect.

Some more in depth reading can be found here if you're interested:
http://physics.bu.edu/~duffy/py106/PhotoelectricEffect.html

Answer 2

The energy of the photon is absorbed by the electron, which is used to overcome the potential barrier that is the work function of the metal. If any energy is left after doing so, it is in the kinetic energy of the electron. Remember that photons are just particles of energy.

It doesn't disappear, nor does it remain, it just changes form from radiant energy to kinetic energy of the electron.

Answer 3

This is known as the photoelectric effect.

The photon energy is absorbed by an electron on the metal, which is excited. This energy is used to overcome the work function of the metal, and the electron is emitted.

Answer 4

The photon collides with an electron. Like when you throw a ball at another ball and they spin off.

Answer 5

Hi ZhangA,

The problem with that analogy is that after the collision there are still two balls. When a photon is absorbed by an electron, then the electron is the only particle remaining. A better analogy would be the case of the two balls colliding and coalescing into one single ball.