How does refraction really work

  • Context: Graduate 
  • Thread starter Thread starter peter.ell
  • Start date Start date
  • Tags Tags
    Refraction Work
Click For Summary

Discussion Overview

The discussion revolves around the mechanisms of light refraction, addressing questions about the behavior of light in different media, the reasons for varying degrees of refraction for different wavelengths, and the nature of dispersive versus non-dispersive media. Participants explore both conceptual and technical aspects of these phenomena.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions why light bends when it slows down, suggesting that it should continue in the same direction after being absorbed and emitted by electrons.
  • Another participant argues that light does not "bend" but rather follows a curved path due to the medium, likening it to a car following a curved road.
  • A participant seeks clarification on the mechanisms occurring in materials like glass that lead to this "illusion" of bending.
  • There is mention of light's momentum affecting the angles of refraction for different wavelengths, with blue light taking a different angle than red light.
  • Participants discuss the difference between dispersive and non-dispersive media, with questions about how some materials can slow light without being dispersive.
  • One participant expresses confusion about the purity of colors in a rainbow, questioning why we see distinct colors despite the overlapping refraction of different wavelengths.

Areas of Agreement / Disagreement

Participants express differing views on the nature of light bending and the mechanisms behind refraction. There is no consensus on the explanations provided, and multiple competing ideas remain present in the discussion.

Contextual Notes

Participants' questions highlight limitations in understanding the underlying physics of light behavior in various media, including assumptions about absorption and emission processes, as well as the definitions of dispersive and non-dispersive materials.

peter.ell
Messages
42
Reaction score
0
I've looked into refraction and diffraction of light, but there are a few things that I don't understand, if you know any of the answers to these questions, please help me:

1.) Why does light bend when it slows down instead of just continuing on in the same direction after being absorbed, held, and then emitted by the electrons in the medium? Why don't the electrons emit the light in the same direction after they absorb it? And how does simply increasing the delay between absorption of light and emission of light cause it to bend more? This doesn't make much sense.

2.) Why are different wavelengths of light refracted to different degrees? I know it's because different wavelengths are slowed to different degrees, but what causes this? Aren't different wavelengths absorbed or transmitted depending on how the electrons in a specific material interact with each wavelength of light, yet all transparent materials slow blue light more than red light, why? What causes does one wavelength travel slower than another?

3.) What's the difference between a dispersive medium and a non-dispersive medium? How can some materials slow light down without being dispersive?

4.) How is it possible for the colors of a rainbow to be so pure? Given what I learned about the light paths for different colors in a rainbow, I know that red light is not only refracted at the angle where red is seen in a rainbow, but also at all the other angles. Given this, it means that, while green light is not refracted at the top of a rainbow where red is, red happens to be refracted where green is... which should mean that we would not be able to see any of the colors in a rainbow except for red and whatever the combination of red and all the other colors turns out to be. Yet we don't, why not?

My utmost thanks for helping me understand these questions!
 
Science news on Phys.org
Light does not "bend" when "slowed down"
The medium might "bend" the totality of a photons passage, but the light itself does not bend.

Think of a car in a curve. The path bends but the car does not. The car follows the path, giving an illusion of bend.
 
ok that's an interesting answer

since this "illusion" is a physically measurable quantity. what is the meachanism in the material, say glass, that is occurring ?

Dave
 
Right. That is a question more suited for the experts(or the FAQ"S section) than I.
 
http://www.vega.org.uk/video/subseries/8
You might want to watch the Feynman lectures on light.
And light has momentum so that might be why blue light takes a different angle in glass than red light.
And you can get the refracted angle and reflected angle by applying Maxwells equations to the material and it will depend on
<br /> \epsilon and \mu for that material
 
Last edited:
Thanks Cragar listening to those lectures now have heard many of his ones over the years. a very brilliant guy huh !

Dave
 

Similar threads

  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 207 ·
7
Replies
207
Views
14K
  • · Replies 40 ·
2
Replies
40
Views
5K
  • · Replies 9 ·
Replies
9
Views
3K
  • · Replies 9 ·
Replies
9
Views
4K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 41 ·
2
Replies
41
Views
5K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 7 ·
Replies
7
Views
3K
  • · Replies 5 ·
Replies
5
Views
3K