PHYS 2004 Lecture Notes - Lecture 21: Electron Temperature
1 Dec 2017
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Let the cathode be the point of zero potential energy. Conserving energy as the photoelectron moves to the anode: When the potential difference causes the very fastest electrons to have kf = 0, this is the stopping potential: Classical physics cannot explain the existence of a threshold frequency f0. It cannot also explain the observation that the current starts instantly. If the photoelectrons were due to thermal emission, it should take some time for the light to raise the electron temperature sufficiently high for them to escape. More intense light should heat the electrons to a higher temperature. This should increase the kinetic energy of the photoelectrons and hence increase the stopping potential.
