Photons and transparency....who's right?

  • Thread starter JFS321
  • Start date
  • Tags
    Photons
In summary, there are many conflicting answers about what happens to photons in a solid medium. Some say that they are absorbed and re-emitted, while others state that they pass through unaffected. It is unclear which model is correct.
  • #1
JFS321
75
6
All, I have read as much as I can find online regarding this topic and there are so many conflicting answers that it is insane.

First, many sources identify photons vibrating the electrons in a transparent material in such a way that the net effect is to pass the photons out the other end of the medium. In this case, it seems to me that photons are being absorbed and re-emitted by each electron on the way through. HOWEVER, other sources state that photons pass through the medium (such as glass) and are not affected because they do not have sufficient energy to be "absorbed" by the electron...in other words...no interaction occurs.

1. But, is it not correct to say that anytime a photon interacts with an electron that it DOES absorb the energy, but perhaps not enough to jump energy levels?

2. In the case of reflection, the electron would absorb enough energy to jump to a higher state, and then re-emit the photon again as light. Therefore, reflection also requires an absorption of energy first, too. Correct?

Thanks in advance.
 
Science news on Phys.org
  • #2
It is horribly complicated to describe light in materials using photons. To do it right would require to treat the whole system in QED - quantum electrodynamics. If you want to understand what is going, a classical picture with electromagnetic waves and Lorentz oscillators is much more accessible.
 
  • #3
So, is there even necessarily a correct mental model to have regarding the behavior of photons in a transparent medium?
 
  • #4
Perhaps a more specific question. Is it correct to say that any time a photon interacts with an electron, it is absorbed? Or, can you ever think of a photon reflecting from an electron as billiard balls would?
 
  • #5
A transparent medium like glass contains electrons that are bound more strongly than the photon energy. So you cannot describe this with just the interaction between a photon and a free electron. Only for free electrons you could do that: the Compton effect, conservation of energy and momentum, like billiard balls.
 
  • #6
JFS321 said:
So, is there even necessarily a correct mental model to have regarding the behavior of photons in a transparent medium?

Please start with our FAQ

https://www.physicsforums.com/threads/do-photons-move-slower-in-a-solid-medium.511177/

Zz.
 
Last edited by a moderator:

1. What are photons?

Photons are particles of light that are the fundamental unit of electromagnetic radiation. They have zero mass and travel at the speed of light.

2. How do photons interact with materials to determine transparency?

Photons can interact with materials in three ways: reflection, absorption, and transmission. The properties of the material, such as its atomic structure and density, determine how the photons will interact and whether the material will be transparent or not.

3. Why do some materials allow photons to pass through while others do not?

The atomic structure of a material determines how tightly the electrons are bound to the nuclei. When photons interact with the material, they can either excite the electrons and cause them to move, or they can be absorbed by the electrons. Materials with more loosely bound electrons tend to be more transparent because the photons are less likely to be absorbed.

4. Who is right in the debate about photons and transparency?

The concept of photons and transparency is well-established in the scientific community and is supported by a large body of evidence and experiments. However, there may be differing opinions or interpretations among scientists about certain aspects of this topic. Ultimately, the evidence and data will determine who is "right" in a scientific debate.

5. How is the transparency of a material measured?

The transparency of a material can be measured using a spectrophotometer, which measures the amount of light that is transmitted through the material at different wavelengths. This data can then be used to calculate the material's transmittance and absorbance, which are used to determine its transparency.

Similar threads

I Stimulated Emission & Emitted photon direction
    • Optics
Replies
1
Views
960
Are these explanations for color/light-absorption correct?
    • Optics
Replies
5
Views
1K
Classically, how can I explain Reflection?
    • Optics
Replies
4
Views
693
Light in a medium: do phonons store light energy?
    • Optics
Replies
1
Views
917
I The electron is not point-like?
    • Quantum Physics
Replies
21
Views
1K
Few questions on light interacting with atoms
    • Optics
Replies
4
Views
1K
I The speed of one photon through a transparent medium
    • Special and General Relativity
3
Replies
74
Views
2K
Lower speed of light inside a transparent medium
    • Optics
Replies
17
Views
2K
I Do atoms recoil when emitting a photon?
    • Quantum Physics
2
Replies
38
Views
3K
Photons passing through transparent material
    • Optics
Replies
2
Views
1K

Hot Threads

Recent Insights

Back
Top