# What is the difference between Compton and Rayleigh scattering?

• mycotheology
In summary, Compton scattering is a process where x-rays or gamma rays collide with an electron, causing the photon to lose energy and convert to a lower wavelength. On the other hand, Rayleigh scattering is a phenomenon where light is scattered off particles much smaller than its wavelength, resulting in the same frequency of the scattered radiation. The fundamental difference between these two types of scattering is the change in frequency/wavelength of the scattered radiation, which is only observed in Compton scattering.
mycotheology
So compton scattering is where x-rays (or gamma rays) collide with an electron and sends it flying. In the process, the incident photon loses energy and is converted to a lower wavelength.

According to wikipedia, Rayleigh scattering is the scattering of photons by particles which are much smaller than the photons wavelength. In Rayleigh scattering, do photons lose energy and change wavelength in the same way they do in Compton scattering? What would be the fundamental difference(s) between these 2 types of scattering?

Hello mycotheology,

welcome at PF. Rayleigh scattering of radiation is a scattering of light off particles (atoms, molecules) much smaller than the wavelength of the light. For example, scattering of visible light in the atmosphere. The scattered radiation has the same frequency as the incoming radiation. Rayleigh's theory describes light as electromagnetic wave and no photons are used in the description.

Compton in 20's studied the process when the X-rays are scattered of the electrons in matter. He found that the scattered radiation has different frequency (lower) than the frequency of the incoming radiation. He explained this as an inelastic collision between the electrons and light quanta; light quanta lose some energy in the collision with electrons and go on with lower energy. By the Planck-Einstein relation between the energy of the light quantum and the angular frequency of the corresponding wave
$$E = \hbar \omega$$
the corresponding scattered wave has lower frequency.

## 1. What is Compton scattering?

Compton scattering is a type of scattering that occurs when a photon interacts with an electron. During this process, the photon loses energy and changes direction, while the electron gains energy and moves in a different direction.

## 2. What is Rayleigh scattering?

Rayleigh scattering is a type of scattering that occurs when a photon interacts with a small particle, such as an atom or molecule. During this process, the photon is scattered in all directions, but the scattered light is predominantly in the same direction as the incident light.

## 3. What is the main difference between Compton and Rayleigh scattering?

The main difference between Compton and Rayleigh scattering is the size of the scattering particles. Compton scattering involves larger particles, such as electrons, while Rayleigh scattering involves smaller particles, such as atoms or molecules.

## 4. How does the energy of the incident photon affect Compton and Rayleigh scattering?

The energy of the incident photon has a greater impact on Compton scattering compared to Rayleigh scattering. In Compton scattering, the energy of the photon is transferred to the electron, resulting in a change in wavelength and direction of the scattered photon. In Rayleigh scattering, the energy of the photon remains the same and only the direction of the scattered light is affected.

## 5. What are some practical applications of Compton and Rayleigh scattering?

Compton scattering is used in medical imaging techniques such as X-ray computed tomography (CT) scans. Rayleigh scattering is responsible for the blue color of the sky and is also used in various technologies, such as optical fibers and radar systems.

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