Photoelectric Effect

[karinaseth_1A]

In Monday's lecture, Dr. Lavelle talked about the photoelectric effect where even with high intensity light, an electron will not be emitted from metal unless the energy of the incoming photon of light is greater than the energy required to remove the electron. What exactly does intensity of light refer to? Is it the number of incoming photons of light or the frequency/wavelength of light?

[Brooke Yasuda 2J]

When you look at light as a wave, the intensity of light refers to the amplitude of the wave. In the world, you will see the increase in the amplitude of a wave as an increase in the brightness of the light source.

[Tiffany_Chen 2K]

Intensity of the light relates back to how scientists previously thought light could only behave as a wave, thus the thinking of how increasing the intensity of the light (wave amplitude) would increase the energy needed to eject the electrons.

However, this model failed and led to the particle model of light, where increasing the frequency/decreasing wavelength had a direct effect on increasing the energy (so light was observed to have particle-like properties of electromagnetic energy).

[erica thompson 4I]

In response to Brooke above, I think he clarified that it's more about the frequency than the amplitude, as you have to think of each atom separately (like the water flowing example).

[Sanjana Borle 2K]

Dr. Lavelle emphasized in lecture that intensity of the light did not matter when it came to exciting the electron because it only increased the amplitude, not changing the wavelength or frequency. But when other frequencies are used, they do have the potential to remove an electron from the surface.