Page 1 of 1

### Light Intensity

Posted: Mon Oct 15, 2018 12:20 am
What happens if the energy per photon is greater than the energy needed to remove an electron?

### Re: Light Intensity

Posted: Mon Oct 15, 2018 12:40 am
Using this equation: E(photon) - E(removed e-) = E(kinetic). you can solve for the difference in energy for kinetic.

### Re: Light Intensity

Posted: Mon Oct 15, 2018 9:04 am
The difference between energy per photon E(photon) and the energy needed to remove an electron E(e-) would give you the kinetic energy E(k).
E(photon) - E(e-) = E(k)
In turn, E(k) = 1/2 MV^2, where M is the mass of the electron and V is the velocity of the electron.

### Re: Light Intensity

Posted: Mon Oct 15, 2018 3:27 pm
The energy of the photon must be equal to or greater than the energy required to remove an electron. Therefore, if the photon energy is greater, then the electron will be removed. However, due to conservation of energy there will be an excess of energy. The excess energy can be identified as the kinetic energy of the electron. Higher energy photons than necessary will result in electrons being emitted with higher kinetic energy.

### Re: Light Intensity

Posted: Mon Oct 15, 2018 3:46 pm
The kinetic energy that the posts above have described are referring to the physical velocity that the electron has left over after it is ejected from the metal sheet. If there was only just enough photon energy to eject the electron, there would be no energy left over to move the electron.