Why are some materials transparent?

In summary, the video from Nothingham University (Sixty Symbols) explains that some materials are transparent due to the energy gap between excited states of electrons. If photons with lower energies pass through, they will not interact with the material and pass through. However, the speed of light slows down in materials like glass due to the photons being absorbed and reemitted. Both quantum and classical explanations can be used to understand this phenomenon. Looking into light scattering theory may provide more insight.
  • #1
center o bass
560
2
Hey! I just saw a video on youtube from the guys at nothingham university (sixty symbols) where they explained that some materials are transparent due to the energy gap between the excited states of the electrons in the material. If photons come in at lower energies they will not interact with the material and pass right trough. The video is found here:



However, if the photons pass right trough, how come the speed of light slows down in for example glass? I've heard that the reason that this happens is precisely because the photons get absorbed and reemitted.

Both quantum and classical explenations are appreciated.
 
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  • #2
Please start by reading the FAQ sub forum in the General Physics forum.

Zz.
 
  • #3
ZapperZ said:
Please start by reading the FAQ sub forum in the General Physics forum.

Zz.
Thanks Zz, your explanation there were illuminating. Do you know if there are some classical approaches for explaining the apparent slowing down of the speed of light, reflection and transmittion?
 
  • #4
center o bass said:
Thanks Zz, your explanation there were illuminating. Do you know if there are some classical approaches for explaining the apparent slowing down of the speed of light, reflection and transmittion?
You could look into light scattering theory
- https://www.physicsforums.com/showthread.php?p=3772953
 

1. Why are some materials transparent?

Transparency in materials is determined by their molecular structure. Materials that are transparent have molecules that are arranged in a way that allows light to pass through them without being scattered or absorbed.

2. What makes a material transparent?

The transparency of a material depends on how closely packed the molecules are and how they are arranged. Materials with loosely packed molecules that are arranged in a regular pattern tend to be transparent.

3. Why do some materials allow light to pass through them?

Materials that are transparent have molecules with a specific shape and size that allow visible light to pass through them. This means that the molecules do not absorb or reflect light, making the material appear transparent.

4. What is the difference between transparent and opaque materials?

Transparent materials allow light to pass through them, while opaque materials do not. This is because opaque materials have molecules that are densely packed and/or arranged in a way that absorbs or reflects light.

5. Can a material be both transparent and opaque?

In some cases, a material can exhibit both transparent and opaque properties. For example, glass is transparent to visible light, but opaque to ultraviolet light. This is because the molecular structure of glass allows visible light to pass through, but absorbs ultraviolet light.

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