Change in the direction of propagation of a wave when its transmitting medium changes.

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22
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5answers
2k views

Why isn't the sunset/sunrise rainbow-colored

When the sun is rising/setting, it goes through a phase where the light is bending from the atmosphere. I believe this image will explain much better than I ever could. Now, if light goes through ...
21
votes
4answers
2k 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 ...
21
votes
3answers
2k views

Why do prisms work (why is refraction frequency dependent)?

It is well known that a prism can "split light" by separating different frequencies of light: Many sources state that the reason this happens is that the index of refraction is different for ...
19
votes
2answers
3k views

How are classical optics phenomena explained in QED (Snell's law)?

How is the following classical optics phenomenon explained in quantum electrodynamics? Reflection and Refraction Are they simply due to photons being absorbed and re-emitted? How do we get to ...
18
votes
3answers
2k views

What really cause light/photons to appear slower in media?

I know that if we solve the maxwell equation, we will end up with the phase velocity of light is related to the permeability and the permittivity of the material. But this is not what I'm interested ...
14
votes
7answers
10k views

What determines color — wavelength or frequency?

What determines the color of light -- is it the wavelength of the light or the frequency? (i.e. If you put light through a medium other than air, in order to keep its color the same, which one would ...
14
votes
2answers
559 views

Would you see a rainbow from refraction when the sun is in front of you?

I know how rainbows are formed, and why. Usually it is said that the Sun must be behind the observer, in order for its light to be totally reflected inside the droplet and then reach the observer. ...
13
votes
4answers
1k views

Looking for the actual reason of refraction explained precisely without analogies

I'm a high school teacher trying to teach my students (15year olds) about refraction. I've seen a lot of good analogies to explain why the light changes direction, like the marching band analogy, that ...
13
votes
2answers
5k views

How does a photon travel through glass?

This was discussed in an answer to a related question but I think that it deserves a separate and, hopefully, more clear answer. Consider a single photon ($\lambda$=532 nm) traveling through a plate ...
12
votes
3answers
783 views

Can the speed of light become complex inside a metamaterial?

The speed of light in a material is defined as $c = \frac{1}{\sqrt{\epsilon \mu}}$. There are metamaterials with negative permittivity $\epsilon < 0$ and permeability $\mu < 0$ at the same time. ...
9
votes
2answers
292 views

Effect of gravitation on light

Einstein predicted that the gravitational force can act on light. This was verified in one solar eclipse that light from a star near to the sun's disc bent due to Sun's gravity as predicted. Since ...
9
votes
2answers
946 views

Why do mirages only appear on hot days?

A previous question asked why the road sometimes appears wet on hot days. The reason is that when there's a temperature gradient in the air, it causes a gradient in the index of refraction, causing ...
8
votes
2answers
396 views

Do photons age in a medium?

According to special relativity, time starts to slow down as we increase our speed and eventually stops once we get to the speed of light. By that logic, photons don't age in a vacuum state as, to us, ...
8
votes
2answers
128 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 ...
8
votes
3answers
446 views

Why do rainbows have distinct colors?

When I searched on the Internet for the reason of formation of rainbows, I got many explanations like this one & this. All the explanations consider only one spherical water droplet (like this ...
8
votes
1answer
72 views

Do we have 2 minutes of extra morning?

my physics teacher told me about the refraction and its applications one of them was 2 minutes of early sunrise and after she explained this effect she concluded that days are 2 minutes longer than ...
8
votes
6answers
3k views

Why does light change direction when it travels through glass?

This was explained to me many years ago, by a physics teacher, with the following analogy: "If someone on the beach wants to reach someone else that is in the water, they will try to travel as much ...
7
votes
4answers
5k views

Eyes open under water

Yesterday I looked underwater with my eyes open (and no goggles) and I realized I can't see anything clearly. Everything looks very, very blurry. My guess is that the eye needs direct contact with air ...
7
votes
3answers
1k views

Does light change color on its way through a window? [duplicate]

Looking at the refractive index of glass, it's around $1.6$. Then the speed of light $x$ through light should be given by $$ 1.6 = \frac{3.0\times10^8}{x}, $$ so $x$ is about ...
7
votes
2answers
806 views

Photon energy - momentum in matter

$E = h\nu$ and $P = h\nu/c$ in vacuum. If a photon enters water, it's frequency $\nu$ doesn't change. What are its energy and momentum : $h\nu$ ? and $h\nu/c$ ? Since part of it's energy and momentum ...
6
votes
3answers
3k views

How can I determine transmission/reflection coefficients for light?

When light rays reflect off a boundary between two materials with different indices of refraction, a lot of the sources I've seen (recently) don't discuss the relation between the amplitude (or ...
6
votes
1answer
585 views

How does sun light after it has passed window's pane still heat me up?

I believe it is so because most of photons' energy has successfully passed the glass. But is it so? And how can I roughly estimate part of light's energy which will pass obstacles like glass? And how ...
6
votes
1answer
232 views

How can I estimate the elasto-optic coefficients ($p_{11}$ and $p_{12}$) of a material?

I am attempting to estimate the elasto-optic coefficients ($p_{11}$ and $p_{12}$) of $\mathrm{TiO}_2$ and $\mathrm{ZrO}_2$, where $p_{11}$ and $p_{12}$ refer to the elements of a strain-optic tensor ...
5
votes
5answers
3k views

How to bend light?

As we all know that light travels in rectilinear motion. But can we bend light in parabolic path? If not practically then is it possible in paper? Has anyone succeeded in doing that practically ?
5
votes
4answers
9k views

Why frequency doesn't change during refraction?

When light goes through one medium to another it's velocity and wavelength changes. Why frequency doesn't change in this phenomenon?
5
votes
2answers
318 views

Can two media have same refractive indices?

Can two mediums placed under same conditions* ever have same refractive indices? *Pressure, temperature,etc.
5
votes
3answers
3k views

Can anyone explain to me why light is not dispersed into a spectrum through a parallel glass slide, but only through a prism?

The question pretty much sums up what I need to know. Why is it that light only gets dispersed into a spectrum when travelling through two non-parallel sides(like a prism) and not through something ...
5
votes
2answers
39k views

Why does wavelength change as light enters a different medium?

When light waves enter a medium of higher refractive index than the previous, why is it that: Its wavelength decreases? The frequency of it has to stay the same?
5
votes
3answers
756 views

How do “holographic plates” work?

I asked a question about laser stage lighting over at Audio Video Production, and received an excellent answer that explained that laser clusters are generated from a single beam via something called ...
5
votes
2answers
146 views

Which electromagnetic radiation is faster in water, microwaves or light?

Well I've been asked this question, but I haven't been able to come with an answer yet using books and some web searches. The point is as the title says, to answer the question with the whole ...
5
votes
2answers
84 views

Why does light travel in a straight line through a liquid?

So I was reading a document that stated that when traveling through a material (I'll use a liquid here, maybe water), a photon actually always traveled at 300,000 km/s, it was just that it ...
5
votes
1answer
1k views

Why do some materials reflect (metals) and other materials reflect and refract (glass) from the quantum perspective?

Recently I was asked to explain the difference between reflection and total internal reflection from a purely conceptual standpoint (no math). Let me explain what I already know. Reflection and ...
5
votes
1answer
193 views

Why Negative refractive index is negative

$n=\sqrt{\epsilon \mu }$ Negative refractive index happens when permittivity ($\epsilon $) and permeability ($\mu $)of a material is negative. My question is, if permittivity and permeabilitity of a ...
5
votes
2answers
374 views

Is there a theoretical maximum for refractive index?

May there be materials yet to be discovered which may have a higher refractive index than today's known materials (for wavelengths within the visible range)? Is there a theoretical limit for the ...
5
votes
3answers
2k views

Real and imaginary parts of dielectric constant vs refractive index?

So for a complex dielectric constant $\epsilon = \epsilon_a + i\epsilon_b$, the wave vector and index of refraction are related to it through $k = \frac{\omega}{c}n$ and $n = \sqrt{\frac{\mu ...
4
votes
6answers
4k views

Is it possible to witness a circular rainbow?

What conditions would make it possible to see a naturally occurring fully 360° circular rainbow? Would it even be possible?
4
votes
6answers
3k views

Do photons have acceleration?

Photons travels with the largest speed in our universe, the speed of light. Do photons have acceleration?
4
votes
3answers
601 views

Gravitational lensing or cloud refraction?

My current understanding of gravitational lensing follows When a star or other massive body passes between us and another star, the phenomenon generally labeled 'gravitational lensing' occurs. The ...
4
votes
2answers
387 views

Goldfish perspective

What does the world look like from the Goldfish point of view, from inside a spherical aquarium? If our eyes were inside, would we be able to see the straight lines, focus on different objects and ...
4
votes
3answers
69 views

Why don't fogbows appear on clouds?

As far as I know clouds are lot of small droplets condensed in air. If droplets are large enough we see a rainbow. If they are small we see a fogbow. Although the size of the droplets are big enough ...
4
votes
2answers
224 views

Shape of the rainbow

I have watched Walter Lewin's lecture(http://www.youtube.com/watch?v=6QVbE_tU2sA) which was about the rainbows. But there is still a question bothering me. I understood the first part of the ...
4
votes
2answers
2k views

intensifying a light source

When trying to intensify a beam of light by refracting it through a lens, (as in a lighthouse fresnel system or similar railroad style switch lamp from years past), is the beam intensity increased by ...
4
votes
1answer
281 views

Why does the light at the bottom of the pool form this awesome pattern?

Take a look at the following picture: Why does the light at the bottom of the water form this pattern? I have also seen the same phenomenon in all the swimming pools I've ever visited, of whatever ...
4
votes
1answer
514 views

The Interactions of Light and Matter

So basically, I was trying to find a good answer to the question of how light interacts matter. Namely on the quantum level what causes matter to appear transparent, reflective, opaque, etc I came ...
4
votes
2answers
112 views

Is refraction sharp or smooth?

Refraction: light changes direction of propagation when entering a material with a different refractive index. Does the direction of propagation of light change sharply and almost instantaneously ...
4
votes
2answers
515 views

Physical explanation for why total internal reflection occurs

I have been trying to understand total internal reflection (and have read several posts on this site already). Mathematically, I feel that I understand how the evanescent wave decays exponentially as ...
4
votes
3answers
528 views

Real image with converging lens?

I read in a AQA GCSE book that: A real image is formed by the converging lens if the object is further away from the principal focus/focal point. I did this experiment in class: Here is my ...
4
votes
1answer
173 views

Anisotropic refractive index with isotropic components?

In relation to my question here I wanted to make sure that my physical argument was not flawed. Anisotropic properties, (especially refractive index) is characteristic of a well-ordered solid ...
3
votes
4answers
25k views

Why do diamonds shine?

I have always wondered why diamonds shine. Can anyone tell me why?
3
votes
1answer
337 views

Diver view of refraction

I'm studying the refraction in optics. If a red light monocromatic beam of red light (700 nm) passes from air to water it becomes with a wavelenght of aprox 526 nm. So, my question is: How is going ...