What is basic difference between photoelectric effect and Compton effect? In both case a photon hits a loosely bound electron So whats the difference? We get current in photoelectric effect but not in Compton. Please help whats happening there.

  1. Photo electric effect occur in bound electron, while compton effect occur in free electron.
  2. In photo electron effect, the photo and hence energy of the photon is absorbed by the electron. While in compton effect photon is scattered.
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    $\begingroup$ In photoelectric effect the electron comes out from the metal surface.Does the electron similarly come out from the foil or remain at the foil being only scattered ? $\endgroup$ – SUBHAJIT SAU Jan 23 '16 at 6:26

A better way to analyze this is to realize that in the photoelectric effect, the electromagnetic wave couples two electron states (bound and excited) via the frequency difference which those states share with the electromagnetic wave. In the Compton effect, there is also an electromagnetic wave and two electron states (in a center-of-mass system we can consider them incoming and outgoing) but in this system it is the wavelength, not the frequency difference, which couples the electromagnetic wave to the electron states.

This is most apparent in the case of a head-on "collision" where the superposition of the incoming and outgoing electron states creates an effective diffraction grating of parallel sheets of charge, which is of course totally impervious to an incoming electromagnetic wave.

I explain this in more detail in my blogpost, "The Day I Almost Won the Nobel Prize".


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