Difference Between Compton Effect and Photoelectric effect -

Compton Effect vs Photoelectric effect

Compton Effect and Photoelectric Effect are two very important effects discussed under the wave particle duality of matter. The explanations of Compton Effect and the photoelectric effect led to the formation and the confirmation of wave particle duality of matter. These two effects play a vital role in fields such as quantum mechanics, atomic structure, lattice structure and even nuclear physics. It is vital to have a proper understanding in these fields in order to excel in such sciences. In this article, we are going to discuss what photoelectric effect and Compton Effect are, their definitions, the similarities and finally the differences between Compton Effect and photoelectric effect.

What is Photoelectric Effect?

Photoelectric effect is the process of the ejection of an electron from a metal in the case of incident electromagnetic radiations. The photoelectric effect was first properly described by Albert Einstein. The wave theory of light failed to describe most of the observations of the photoelectric effect. There is a threshold frequency for the incident waves. This indicates that no matter how intense the electromagnetic waves are electrons would not be ejected unless it has the required frequency. The time delay between the incidence of light and the ejection of electrons is about a thousandth of the value calculated from the wave theory. When light exceeding the threshold frequency is produced, the number of emitted electrons depends on the intensity of the light. The maximum kinetic energy of the ejected electrons depends on the frequency of the incident light. This led to the conclusion of the photon theory of light. This means that the light behaves as particles when interacting with matter. The light comes as small packets of energy called photons. The energy of the photon only depends on the frequency of the photon. There are a few other terms defined in the photoelectric effect. The work function of the metal is the energy corresponding to the threshold frequency. This can be obtained using the formula E = h f, where E is the energy of the photon, h is the Plank constant, and f is the frequency of the wave. Any system can absorb or emit only specific amounts of energy. The observations showed that the electron would absorb the photon only if the energy of the photon is enough to take the electron to a stable state.

What is Compton Effect?

Compton Effect or Compton scattering is the process of scattering of an electromagnetic wave from a free electron. The calculation of Compton Scattering shows that the observations can only be explained using the photon theory of light. The most important of these observations was the variation of the wavelength of the scattered photon with the angle of scattering. This could only be explained treating the electromagnetic wave as a particle. The main equation of the Compton scattering is Δλ=λc(1-Cosθ), where Δλ is the wavelength shift, λc is the Compton wavelength, and θ is the angle of deviation. The maximum wavelength shift occurs at 1800


What is the difference between Photoelectric Effect and Compton Effect?

• Photoelectric effect only occurs in bound electrons, but the Compton scattering occurs in both bound and free electrons; however, it is only observable in free electrons. 

• In the photoelectric effect, the incident photon is observed by the electron, but in Compton scattering, only a part of the energy is absorbed, and the rest of the photon is scattered.