About compton's effect of shift in wavelengths

In summary, the conversation discusses the concept of a head-on collision between a photon and an electron in Compton's effect. However, due to the point-like nature of these particles in quantum mechanics, the idea of a precise "moment of impact" is undefined. Different explanations, such as a semi-classical approach or the concept of the electron absorbing and re-emitting the photon, are offered to understand the scattering of these particles. The textbook "Halliday-Resnick-Walker's Physics" is mentioned as a reference, but it is unclear where exactly the concept of a "head-on" collision is stated. Overall, the conversation highlights the complexity and nuances of understanding quantum mechanics.
  • #1
Esfand Yar Ali
15
1
I want to know that ,I have read in many books regarding compton's effect that a photon collides with an electron and this collision is a head-on collision,but if this is a head-on collision then why both these particles are deflected by making a respective angle,don't they should move forward linearly?please answer this question
 
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  • #2
Please provide references that stated that it is a "head-on" collision.

Zz.
 
  • #3
As both the photon and the electron are point particles in standard QFT, it would be basically undefined what "head on" means. Two points can't really hit "head on" since they have no spatial dimension.

There are different ways you can think about the problem, but two billiard balls hitting right head on is probably not a good way. In semi-classical quantum mechanics (Compton's original derivation uses a semi-classical approach, basically appealing to quantum mechanics only in postulating a photon), from which the photon is modeled as an object with momentum p=h/λ, one should probably just think of the two particles as colliding approximately head on, allowing for the photon to scatter at random angles and imparting an angle dependent amount of momentum to the electron.

Another way to think about it, supported by the Feynman diagram for this process, is to think about the electron actually absorbing the photon, and then re-emitting it in a different (random) direction. If this is easier for you to visualize, you can think of it this way too.

Really, quantum mechanics doesn't say much for the "moment of impact" since all the tests we can do are scattering events where we see the initial state (2 particles going in) and the final state (2 particles coming out) but we can't really ever observe the "moment of impact" itself.
 
  • #4
ZapperZ said:
Please provide references that stated that it is a "head-on" collision.

Zz.

you can look at 'Halliday-Resnick-Walker's Physics'
 
  • #5
Quantum Physics is as much interesting as relativity physics and cosmology!
 
  • #6
Esfand Yar Ali said:
you can look at 'Halliday-Resnick-Walker's Physics'

Exactly where? Cite the page number and the passage where this "head-on" collision was stated.

In any case, based on the responses that you had already been given, do you still think that this is a "head-on" collision?

Zz.
 
  • #7
Esfand Yar Ali said:
you can look at 'Halliday-Resnick-Walker's Physics'

Natural language is not nearly as precise as mathematics, and even very carefully edited textbooks sometimes slip up and use language that can be misinterpreted - especially when they're counting on the student working through the accompanying mathematical treatment to clear up any confusion.
 
  • #8
ZapperZ said:
Exactly where? Cite the page number and the passage where this "head-on" collision was stated.

In any case, based on the responses that you had already been given, do you still think that this is a "head-on" collision?

Zz.

now my concepts are clearing a little bit,but I need some more explanations,well thanks for your support!
 

1. What is the Compton effect?

The Compton effect, also known as Compton scattering, is a phenomenon in which the wavelength of a photon changes after colliding with an electron. This was first described by Arthur Compton in 1923 and is a crucial concept in understanding the wave-particle duality of light.

2. How does the Compton effect cause a shift in wavelengths?

When a photon collides with an electron, some of its energy is transferred to the electron, causing it to recoil. The photon's energy is then reduced, resulting in a longer wavelength. This shift in wavelength is known as the Compton shift and is directly proportional to the energy of the photon and the scattering angle.

3. What is the significance of the Compton effect?

The Compton effect provides evidence for the particle nature of light and supports Einstein's theory of relativity. It also has important applications in fields such as X-ray imaging and nuclear medicine.

4. Can the Compton effect be observed in everyday life?

Yes, the Compton effect can be observed in everyday life in the form of X-ray scattering. When X-rays pass through a material, they can collide with electrons and undergo a Compton shift, which can be detected and used for medical imaging purposes.

5. How is the Compton effect related to the photoelectric effect?

The Compton effect and the photoelectric effect are both examples of the wave-particle duality of light. The photoelectric effect demonstrates the particle nature of light, while the Compton effect shows the wave nature of light. Both phenomena involve the interaction of photons with electrons, but in different ways.

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