Questions tagged [refraction]

Change in the direction of propagation of a wave when its transmitting medium changes. The tag does also apply to index of refraction.

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Paint: "Darker When Dry"?

A great question I enjoy bringing up is why are things, in general, "darker when wet". This applies to porous and granular materials like wetted stone, paper, sand etc. It also comes up in ...
mittimithai's user avatar
7 votes
1 answer
467 views

What is the energy loss in total internal reflection?

In total internal reflection light inside a dense medium reflects from the boundary to a less dense medium. Since by Snell's law there is no allowed refracted ray, all energy continues along the ...
Anders Sandberg's user avatar
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What causes materials like Vantablack to have their high optical absorption properties?

As per the title of this post. From reading, I understand that blackbody radiation is a factor I should consider here, with light being absorbed and converted to heat etc. However, what I want to ...
Jenson Holden's user avatar
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Complex part of second-order susceptibility in nonlinear optics

In optics, the absorption of photons by a material can be described by considering the material's susceptibility. For linear absorption (involving a single photon), we think about the imaginary part ...
Liz Salander's user avatar
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What is Curvature of eye lens?

I wanted to know what do we mean by "curvature of eye lens", is it the reciprocal of $r$ i.e $c=1/r$ or is it synonymous to radius of curvature of the eye lens. Moreover how does aperture relate to ...
Anamika Ghosh's user avatar
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Does the intensity of blackbody radiation depend on the speed of light in the medium?

In 1863, in “ON THE CONCENTRATION OF RAYS OF HEAT AND LIGHT, AND ON THE LIMITS OF ITS ACTION”, Clausius wrote in the conclusion: To harmonize the effects of ordinary radiation, without concentration, ...
Cloudyman's user avatar
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Under water light reflection of air in a cup vs water in a cup

The last time I was on vacation I was drinking on the swimming pool, and after I was finished with the drinks I started playing with the 2 plastic cups I had, and noticed that the air produces a ...
Leo's user avatar
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Mathematical approaches to atmospheric refraction

Understanding atmospheric refraction, particularly of ultraviolet, and into the blue part of the visible spectrum is of great interest to me. Although, I have a strong background in trigonometry and ...
3 votes
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Prism deviation angle for small angles

Consider the following scheme for monochromatic light refracting through a prism, with the deviation angle $\delta$:                                               Let $\theta_1\ \wedge\ \alpha\ll1$ . ...
Johann Wagner's user avatar
3 votes
2 answers
967 views

Intrinsic impedance of a medium

I am trying to understand what the intrinsic impedance of a medium means. I understand the mathematical definition of it, but it doesn't speak much about the concept to me. What does intrinsic ...
user207787's user avatar
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Time lag between observed electrical field and polarity of light?

I was listening to the Feynman lectures on physics Vol. 3, Ch.2 the other day, and he was talking about the relationship between light polarity and the electric field of light as it is transmitting ...
Chris's user avatar
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What is the upper bound for the index of refraction of space?

It seems that gravitational waves and gamma waves travail at about the same speed, arriving within seconds of each other over distances in the ranges of $10^6$LY. Naively, I would assume this caps the ...
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Can a powder be transparent?

I know that even glass powder is white due to refraction and internal reflection. So to be transparent, the index of refraction would need to be close to 1 (air). I also know that the index of ...
Daniel F's user avatar
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Photons when passing through matter

I am wondering whether there is a simple—or complicated—way to explain from a purely quantum mechanics (or QFT) viewpoint what happens to the photons when they go through some material whose index of ...
untreated_paramediensis_karnik's user avatar
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382 views

False sunset and false sunrise time estimation

False sunset and false sunrise are described . Here is a sample day rise and set time according to AccuWheather site and calculated value of sunrise and sunset in my country. Could you please help ...
Halis Yılboğa's user avatar
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How is light trajectory affected by the trajectory of environment it passes through?

There's a sci-fi concept of slow light that I find very amazing: Imagine a glass material that has index of refraction $n$ say, $3,000,000,000$ which means: $$v_{glass} = \frac{c_{vacuum}}{n} = 0....
Tomáš Zato's user avatar
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Nonlinear refraction index of vacuum above Schwinger limit

This question is more about trying to feel the waters in our current abilities to compute (or roughly estimate) the refraction index of vacuum, specifically when high numbers of electromagnetic quanta ...
lurscher's user avatar
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Why is refractive index equals to speed of light upon phase velocity and not group velocity?

We have been using group velocity for most purposes as its the velocity with which the wave packet travels, they why do we use phase velocity for calculating refractive index.
Kanishk pratap singh's user avatar
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Photon momentum in Snell's law of refraction

In the drivation of Snell's law for light as EM waves, we have the wave vector components parallel to the interface $k1\parallel$ = $k2\parallel$ as shown in the picture. From $k_{1x} = k_{2x}$, we ...
Leon Chang's user avatar
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71 views

What are the Fresnel formulas for acoustics?

While it's not too difficult to derive Snell's Law for acoustics e.g. from Huygen's principle like for light, I find surprisingly little resources on an equivalent to Fresnel formulas linking the ...
Tobias Kienzler's user avatar
2 votes
2 answers
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Do Normal Incidence contradicts the definition of refraction?

Professor told our class that if someone wants to define refraction in words, it can be done as the following, The deviation of light from its path when it passes from one medium to another is called ...
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2 votes
2 answers
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What are some liquids with high ranges of refractive index with change in temperature?

I need to run an experiment on the effect of temperature on refractive index of a liquid, and in order to make the change most visible and have the lowest percent uncertainty I need the change in ...
PP Epic's user avatar
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Is it possible to measure the temperature of a candle by the diffraction method?

I am reading a book " Physics, Fun and Beyond" by Eduardo de Campos Valadares. In his book, he is mentioning about an experiment "bending laser beams with hot air." I am posting a ...
ofenerci's user avatar
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Why does refractive index increase with concentration of the medium?

I learnt that lights decrease velocity in a medium during absorbance and emission of its energy in the charged particles in the medium. From the Beer's law, I read that absorbance is directly ...
Wishes's user avatar
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Analysis of the reflection in metal

In order to solve the reflexion in a material with a complex index the solution I've found on textbooks is to define $\hat{n}\cos{\phi}:=a+bi$ where $\hat{n}=n_r+n_ii$ is the complex index and then ...
Mikel Solaguren's user avatar
2 votes
0 answers
93 views

Why do seismic P waves convert to S waves at an interface?

Why does a P wave refract and become an S wave when it hits an interface? What is the mechanism behind this? If P waves are longitudinal and S waves are transverse, how can this change occur?
Hachi And Me's user avatar
2 votes
1 answer
97 views

Tangential rainbows?

My kids just made me aware of a rainbow phenomenon I have never heard of before, happening in the sky up above our heads. I have heard of (and seen) double rainbows before, and I was aware that it's ...
Trevortni's user avatar
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What can be the possible causes for variation in stress-induced birefringence in an isotropic material?

Birefringence is the phenomenon of a material having a refractive index that depends on the polarization and propagation direction of light. When an unpolarized light passes through such a material, ...
Manas Pandey's user avatar
2 votes
0 answers
44 views

Calculating the refractive index of water with the Ewald-Oseen formula

The Ewald-Oseen theorem gives the expression $$n=\sqrt{1+\frac{i\sigma}{\epsilon_0\omega}}$$ for the refractive index of a material of conductivity $\sigma$ for an electromagnetic wave with angular ...
Rain's user avatar
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1 answer
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How to estimate change in refractive index due to acoustic wave travelling in quartz?

I'm studying acousto-optic modulators and the basic principle of operation is that an acoustic/sound wave is made to travel along one direction of a crystal (say quartz). This creates a pressure wave ...
Danyel's user avatar
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Shouldn't a part of the ray have to travel $\frac{\lambda_2}{2}$ extra path in the medium $n_2$?

Basically, my teacher had given the class a question regarding thin film interference that, there is a medium with refractive index $n_1$ below that there is another medium with thickness $t$ with ...
Koustubh Jain's user avatar
2 votes
0 answers
210 views

How does a broadband dielectric Mirror work?

It is widely known that dielectric mirrors work with several layers of at least two materials which differ in refractive index that are layered, such that partially reflected waves interfere ...
Simon's user avatar
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2 votes
2 answers
54 views

How does a non-infinite monochromatic plane ray of light know which way to refract?

I have been making a simulation of light traveling in medium from classical physics perspective and while trying to makes sence of a traveling wave packet i realized i don't understand something very ...
KrNeki's user avatar
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2 votes
1 answer
395 views

What is aperture of a lens?

I read that aperture of a lens is the surface from which refraction takes place and it is represented by the diameter of the lens. So, by saying that the aperture refers to the surface from which ...
Rajdeep Sindhu's user avatar
2 votes
2 answers
101 views

How do we know that light cannot travel faster than it does?

We assume the speed of light in vacuum is its maximum speed but can we not assume that it could be faster, or slower?
m.wes's user avatar
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0 answers
64 views

If the velocity of light is different in different medium is it wavelength changes or frequency changes?

We know that the velocity of light is equal to the product of it's wavelength and frequency. And when light goes from vacuum to any other medium it's velocity changes depending the mediums refractive ...
Arafat Hossen's user avatar
2 votes
3 answers
539 views

What is the refraction index in the upper atmosphere (e.g. thermosphere)?

I've been searching for the refraction index in the upper layers of atmosphere such as stratosphere and thermosphere but I can't find it, all that I've seen is all equations without any numbers that I ...
RendezvousRama's user avatar
2 votes
0 answers
31 views

Maximum intensification by refraction

Suppose that a beam of light in a medium with index of refraction $n$ reaches the surface of the medium, with vacuum on the outside. Its incident angle with respect to the normal is $\theta$. Only a ...
user avatar
2 votes
0 answers
129 views

When does refraction begin?

As a wave function (a single quantum of field excitation) enters a refractory medium, does it begin to refract only after the entire wavelength has entered or does the leading edge of the wavelength ...
Anomalous Howard's user avatar
2 votes
0 answers
316 views

WHY do waves diffract - what is the mechanism behind the diffraction?

Having recently studied wave diffraction at an introductory level, I don't feel that I understand why waves diffract like they do. What is it about the obstacle or the waves interaction with it which ...
gbro3n's user avatar
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optical homogeneity of organic thin films

Prior to further analysis (like variable angle ellipsometric spectroscopy) I check thin films of organic materials vacuum deposited on glass substrates for their optical homogeneity under lineraly ...
Buttonwood's user avatar
2 votes
0 answers
773 views

What happens when light is reflected from a surface moving in a medium with a huge refractive index?

Imagine a mirror is moving away from a light source in a substance through which the speed of light is very slow -- so slow that the speed of the mirror is close to being the same as the speed of the ...
Eric Czech's user avatar
2 votes
0 answers
245 views

If a beam of light follows the path $y(x)=y_0\sin(x/y_0)$, what is the index of refraction?

An exam question that showed up while I was studying: A plane wave refracts and follows a ray given by the equation $y=y_0\sin(x/y_0)$ where $y_0$ is a constant. Find the refractive index $n(y)$ ...
Pricklebush Tickletush's user avatar
2 votes
0 answers
185 views

Modeling a spray painted polyurethane surface reflection

I'm modeling light interaction/reflection from a fiberglass surface with polyurethane epoxy (that is very reflective) that has been spray painted with a matte black paint. I'm looking for some input -...
gallamine's user avatar
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Microscopic model of complex refractive index

In my Electromagnetic Optics class, we tried to reconcile the microscopic (optical) properties of matter with its macroscopic counterparts, and one of the most challenging properties is the (complex) ...
AlanFox86's user avatar
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1 vote
1 answer
92 views

When light passes from one medium to another. Depending on the density, it would experience a change in velocity. Why would its vector change as well?

For example, when light passes through water its velocity decreases and refraction occurs. Why? Why is there a change in direction. If I slow down a car I don’t suddenly turn left.
A new learner's user avatar
1 vote
0 answers
21 views

Fresnel Equations and an Opaque Surface?

I'm trying to make sense of what actually happens to light when it interacts with an opaque surface. The fresnel equations give us the proportion of light which is reflected off the surface of a ...
Chris Gnam's user avatar
1 vote
0 answers
52 views

The speed of light in medium with different frequency

We know that the speed of light in vaccuum can be expressed as $c=\frac{1}{\sqrt{\mu_0\epsilon_0}}$ and thus the speed of light in vaccuum is thus $$v=\frac{1}{\sqrt{\mu\epsilon}}=\frac{c}{\sqrt{\...
Pck Tsp's user avatar
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1 vote
1 answer
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Snell's Law- Extraordinary ray

I applied the snell's law to find the angle of refraction of the Ordinary and Extraordinary ray. And I got the correct answer 3.51. But I know my approach to the question is wrong because I applied ...
Akshat Shrivastava's user avatar
1 vote
1 answer
108 views

Why is deep open ocean blue?

If we assume the ocean is sufficiently deep so that the blue light transmitted inside the water gets absorbed completely before it reaches the ocean floor and be scattered back towards the surface, ...
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