# Tagged Questions

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

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### Does time pass slowly in water?

In water the speed of light is slower than it is in vacuum. By special relativity the speed of light is constant. Typically, for the basic explanation of special relativity a clock which has a mirror ...
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### Hildring - Influence of vertical temperature gradient on light beam curvature

In special atmospheric condition it is possible to see coastline that normally is behind the horizon. It is apparently lifted to become visible. In Scandinavian the phenomenon is called 'hildring', a ...
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### Arrow that changes direction home experiment

I saw this cool optical effect in a experiment on Youtube: https://www.youtube.com/watch?v=G303o8pJzls Could anyone explain to me why the arrow points in the opposite direction? I have read ...
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### Is the IoR of water exactly $4/3$?

The index of refraction of water is commonly cited as $n \approx 1.33$, to varying numbers of decimal places. I've never seen a decimal expansion for this value with any digit other than $3$ past the ...
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### Cause behind bending of light in refraction [duplicate]

I know that refraction is caused due to change in speed of light but why does it bends? I also know that during refraction frequency is constant and wavelength is decreased since speed slows down. But ...
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### Rainbow reflected on TV screen? (pic attached)

According to wikipedia, A rainbow is an optical and meteorological phenomenon that is caused by reflection, refraction and dispersion of light in water droplets... Given that we require ...
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### What does the equation of a refracted ray trace mean?

I am doing a ray trace to a refracted vector. I read in some PDF files that: vector($\mathbf{t}$) is the refracted ray, vector($\mathbf{i}$) is the incident ray, the angle $\theta_t$ is the refraction ...
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### Apparent depth and virtual image position

Why does the virtual image appear right on top of the object and not a little to the right, for example? Is it explained by some formula or just symmetry of the geometry?
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### Why do electrons on the surfaces of a lens focus photons instead of scattering them in all directions?

Compton tells us electrons on the surface of a lens should scatter photons, not focus them. Imagine a photon traveling from a pinpoint on the surface of a source object to a silicon atom on a lens ...
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### Snell's law demonstration

I'm a bit confused about a Snell's law demonstration. I'm reading Communication Systems from W. Tomasi. In the chapter 11, the author applies the Snell's law to θent, and -here comes my problem- he ...
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### How to improve the visibility of light without increasing the brightness?

I am not sure whether or not this is the right SE site to post this question on but I'm sure someone will inform me of my mistake soon enough if it is wrong. Basically I am an Electronic Engineer and ...
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### 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 ...
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### How does one show specific thickness and wavelength determine full transmission of electromagnetic waves?

How does one show that thickness and wavelength determine the full transmission between two different dielectric media if the boundary condition equations between two dielectric media are independent ...
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### What does the refractive index depend on? [duplicate]

I've always thought refractive index is dependent on the density of the material. The more denser, the more refraction. But kerosene whose density is higher than water has refractive index less than ...
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### how to trace light after refraction by a camera lens?

I am a programmer and I am doing a camera simulation, I am stuck in a matter of how to know where arrives every ray of light after traveling through the lens and being refracted. Every point of the ...
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### When does a monochromatic beam of light on a reflective surface get completely transmitted?

My book says when when a monochromatic beam of light is normally incident on reflective surface it gets completely transmitted. I am bit confused could you explain me?
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### What polarizes a rainbow?

What polarizes the light from a rainbow. I already did some search and couldn't get a clear answer. All I could find was the light is polarized on the direction light is entering. What happens to the ...
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### How confident can we be that the speed of light in a medium is constant?

I have recently found this article http://news.harvard.edu/gazette/1999/02.18/light.html it tells that physicists have been able to slow the speed of light. Is this hokum? If not how is it possible to ...
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### Why does the ray bend only in one direction?

By snell's law , the refracted ray bend away or towards the normal according to refractive index of the medium. But it can be seen that the refracted ray bends to the right by an angle when a ray of ...
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### Is the speed of photon always $c_0$? [duplicate]

The propagation of light in medium is sometimes interpreted as the photons moving with $c_0$ (the speed of light in vacuum), occasionally absorbed by particles and released again by transition, ...
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### How can frequency be constant during refraction? [duplicate]

When entering from a rarer to a denser medium, the speed of light decreases.I know that the frequency remains constant.But if frequency is cycles/sec then doesn't that mean more speed will lead to ...
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### How would a fractal refract light?

A fanciful Pink Floyd reference has led me to wonder what white light passing through an object with an infinitely complex surface would do. Would it exit from a single chaotically-chosen point on the ...
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### How can a 360 Degree Rainbow be formed? [duplicate]

Just a while ago while I was reading news paper, I saw an amazing article. Someone had caught a photo of a 360 Degree Rainbow. But how is it possible. I mean after refraction the only rainbows that ...
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### How does light speed up after coming out of a glass slab?

As I learned today in school, my teacher told me that when light enters a glass slab it slows down due to the change in density and it speeds up as it goes out of the glass slab. This causes a lateral ...
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### What's the relationship between velocity factor and refractive index?

Wikipedia on velocity factor explains: For optical signals, the velocity factor is the reciprocal of the refractive index. On refractive index, Wikipedia also has an explanation of refractive ...
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### Why phase velocity is related to deflection angle?

Refractive index is a function of velocity in the medium.How is this related to deviation angle inside the medium?
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### Does light change phase on refraction?

I have seen a lot about when light undergoes a phase change when it is reflected. But does it undergo a phase change when refracted and if so why and if not why not?
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### What property of medium is directly related to light propagation speed in that medium? [duplicate]

Refractive index is used to calculate phase velocity of light in medium, other than vacuum. Recently I had a discussion with somebody claiming that light is slower due to magnetic field of atoms. I ...
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### Reflection coefficient as a function of frequency

I am trying to relate the equation for reflection coefficient in oblique mediums to the frequency but can't figure out how the frequency affects the reflection of light. $n_1$= intrinsic impedance of ...
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### Penny dropped in the water: What would you see if transmitted light is parallel to the incident surface

I'm working on a problem which asks what is the greatest diameter of a paper you can use to totally shield a penny dropped in the water from view. The question claims that if the transmitted light ...
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### Why can't we see Rainbows from its end points? [duplicate]

We see Rainbows many times, but we always see them Horizontally or from Sideways. Why can't we see it from under it?/From the point where it starts or ends(end points)? I also want to stress on that, ...
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### Total internal reflection angle [closed]

For what angle does total internal reflection happen? I think that it happens for angle=k*pi where k is an integer with the possible values: 0, 1, 2, 3... Is my assumption correct?
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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.... 1answer 222 views ### Two layers of glass reflection related to wave interference [closed] A highly reflective mirror can be made for a particular wavelength at normal incidence by using two thin layers of transparent materials of indices of refraction n1 and n2 (1 < n1<n2 ) on ... 1answer 32 views ### if you're wearing goggles, will the light beam appear to travel straight? if person A is outside a pool and person B is inside a pool with goggles, won't the light beam travel closer to the normal inside the pool but then away from the normal when it enters the goggles (due ... 1answer 44 views ### Any material to have a significant difference for different colors? I am looking for a material whose refractive index for the colors green, red and blue to have a significant difference to be visible in simple geometrical optics experiments?! We use a microscope and ... 0answers 34 views ### Atmospheric refraction approximation I am studying atmospheric refraction, reading ITU P.834 Effects of tropospheric refraction on radiowave propagation, and I have a question about an approximation. They say that refraction correction, ... 1answer 741 views ### Why doesn't frequency change? [duplicate] I've seen a mathematical example where a wave was made from same source in water and air. but in both medium frequency was same but wavelengths were different in each medium. we know that velocity of ... 2answers 125 views ### Why does electromagnetic refraction happen? Why does refraction happen? In high school textbooks, it is stated that it happens because the speed that electromagnetic waves propagate in the media change. But why cant they continue propagating in ... 2answers 660 views ### Can we get the refractive index of a prism by using white light? Can we get the refractive index of a prism by using white light ? I guess since white light is non chromatic, it is not possible. 2answers 226 views ### Laser Refraction Can you take a laser beam of high intensity and refract it in a way to convert it to a safe level? White light traveling through a prism refracts into the individual wavelengths, could something ... 2answers 302 views ### light ray undergoing total internal reflection thrice inside a prism Can it ever be possible that a light ray going inside a triangular prism of refractive index n having refracting angle A undergo total internal reflection thrice before emerging out? Note:I know it "... 1answer 2k views ### Dependence of scattering on particle size and refractive index How does the intensity of light scattered by a medium depend on the refractive index and the size of the particles dispersed in the medium? I found plenty of literature about the dependence of ... 2answers 726 views ### Why can't we reach the ends of rainbow? Rainbows are spectacular things. But I imagine why we can't reach to the ends of rainbows. Do rainbows have no ends ? If so, why can't we reach at them? If you go closer,they will go further. Why? 0answers 334 views ### In the analogy of turning car wheels related to bending of light while entering glass through air, does that imply that two photons are “connected”? There's a famous analogy that explains the bending of light when it enters glass from air. But doesn't that imply that two photons, represented by the adjacent wheels of the car, are connected by ... 0answers 177 views ### Can time pass for a photon if it's moving in a medium? [duplicate] If time does not pass for a photon traveling at the speed of light, which can only occur when traveling in a vacuum, what happens when it is slowed down by traveling through non vacuum space like ... 1answer 227 views ### How would we see the earth if refraction of light was significantly stronger? On worldbuilding.SE there is a question about the cosmological consequences of a world with super-high refraction and atmosphere opaqueness. I'm assuming the easiest way to minimally change the laws ... 2answers 1k views ### Sellmeier Refractive Index of Standard Air The question: What is the Sellmeier description of the refractive index of air at some reasonable temperature, pressure, and water content? The description must be in the following form:$$ n^2(\...
A sheet of glass is coated with a $500\text{ nm}$ thick layer of oil ($n=1.42$). For what visible wavelengths of light do the reflected waves interfere a) constructively? b) destructively? ...