All Questions
14
questions
1
vote
1
answer
398
views
Deriving the focal length of a graded index lens (GRIN)
I want to find a closed expression of the focal length of a graded index since I don't manage to find any on the internet. I already checked this out: Determining the focal length of a gradient index ...
- 344
5
votes
3
answers
1k
views
What happens to light as it enters a denser medium?
I am a first year undergrad student doing optometry (never done any physics before in my life :( ). I got a question asking what happens when light enters a denser medium. I was told that the ...
- 51
1
vote
4
answers
118
views
About the lowering of the speed of light in non-vacua
I don't understand really why matter interacts with light so as to slow down wavefronts to a speed strictly below $c$, but still preserving that sharp wavefront-like signal.
This is somewhat ...
- 643
2
votes
2
answers
2k
views
If different wavelengths of light have different speeds, how can they move together as a white light in air?
My question is with respect to Newton's experiment of using two identical glass prisms [in which one is inverted with respect to the first one]. When he allowed all the colors of the spectrum to pass ...
4
votes
4
answers
938
views
Why does frequency remain unchanged in light refraction but wavelength doesn't? [duplicate]
Since the frequency of an electromagnetic wave does not change during refraction but the velocity changes, the wavelength must therefore change. But why doesn't the frequency change in the first place?...
- 11.8k
1
vote
1
answer
922
views
Gaussian beam refraction
I'm trying to understand how Gaussian beams interact with matter. Maybe I have a conceptual issue, but is the beam in the image not propagating in the z direction? In that case, I want to understand ...
- 11
1
vote
1
answer
1k
views
Why does light take the path taking the least time?
I know this question has been asked many time but my question is bit different here. What i mean by the above question is that I recently got to learn that light actually does not exclusively take the ...
- 823
-1
votes
1
answer
1k
views
Are images formed due to reflection or refraction and what do we see? HOW?
I am getting extremely confused about what we see as individuals : do we see reflected rays or refracted rays and what does our brain interpret?
The concept has bewildered me for a long time. Googling ...
user116688
2
votes
1
answer
47
views
Boudary conditions for electromagnetical field
I have been studying the interface conditions for the vector fields $\vec{E}, \vec{D},\vec{B}$ and $\vec{H}$, and the following expression made me think a little:
$$\epsilon_2 \vec{E_2}.\vec{n} + \...
2
votes
2
answers
148
views
Why doesn't sunlight ALWAYS get split (into monochromatic) when going through the clouds?
It is my understanding that clouds are largely made up of water, which is known to split white light into its frequency components, and that's why we see rainbows sometimes. My question is, with ...
- 509
0
votes
0
answers
93
views
Index of refraction for travelling EM wave problem
Let $n_1$ be the index of refraction of the first medium and $n_2$ be the index of the second medium.
When $n_2>n_1$, then for an incident angle of $90^{\circ}$ we get a refracted light at a ...
- 7,720
6
votes
2
answers
61k
views
Why is the index of refraction different for different wavelengths? [duplicate]
The index of refraction can be written as
$$n=\frac{\lambda_v}{\lambda_m}$$
where $\lambda_v$ is the wavelength in a vacuum and $\lambda_m$ is the wavelength in the medium. I’ve been told that since ...
- 1,499
15
votes
2
answers
843
views
Which of these theories on why light slows in media are true?
This question is similar to previously asked questions, but the responses to them are confusing and I think it may be better covered by listing out all the potential answers for clarity.
It's a ...
- 532
85
votes
4
answers
40k
views
What is the mechanism behind the slowdown of light/photons in a transparent medium?
So light travels slower in glass (for example) than in a vacuum. What causes light to slow down? Or: How does it slow down? If light passes through the medium, is it not essentially traveling in the "...
- 1,063