Arthur H Compton

Compton effect an evidence for the particle nature of Electromagnetic radiation?

Is Compton effect, discovered by Arthur H Compton an evidence to substantiate and prove the particle nature of electromagnetic radiations?

image credits : PhysicalGeography.net

We can say a Yes and a No simultaneously. But seriously it is a Yes.

What is Compton effect or Compton scattering?

Compton effect an evidence for the particle nature of Electromagnetic radiation
Arthur H Compton (Wikipedia)


It was during the 1920s, Arthur H Compton studied the scattering of energy particles. He found certain properties,and derived them mathematically. When an energy packet,which was described by Max Planck's hypothesis,which is in wave form,hits an electron at rest. Electron is not a wave but a particle,here at rest. The incident energy packet or photon loses some energy. As energy of a photon is directly proportional to frequency, here the frequency reduces after hitting,and fortunately the wavelength increases.

What happens to the electron,which was at rest? It receives the lost energy and like the usual classical picture of gaining kinetic nature. It possesses a positive velocity and scatters away.



Compton effect an evidence for the particle nature of Electromagnetic radiation
Diagrammatic View of Compton Scattering

From the findings of Compton he found that the change in wavelength of incident energy particle depends only on two facts:

  1. Compton wavelength of the rest electron
  2. Angle of scattering


The maximum scattering occurs at 180 degree and the corresponding wavelength change was found to be 4.852 Pico metre. Unfortunately such a change can't be observed with our visible light as this much change in their wavelengths will be negligible to observe. Hence, Compton effect is never shown by visible light. 
Compton effect an evidence for the particle nature of Electromagnetic radiation
Diagram showing Compton scattering through an angle

So who can show?
Only energy particle for who the change of 4.852 picometre is a valuable change. It was identified as X-Rays.
Later it was confirmed that,It was through this single process X-rays are losing their energy while propagating through matter.

The experimental findings and theoretical deductions from Compton's derivation matched with the picture generally shown by classical particles during scattering. But we used wave equations and wave concepts initially. Then how could this be possible?

Finally we were forced to understand that particle nature is inherited in wave nature and vice versa of electromagnetic radiations.

This prove that Compton Effect is an evidence for the particle nature, but it didn't prove it 100% percent the dual nature. That's why I included a Yes and a No in the beginning.

image credits : Wikipedia

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