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3answers
49 views

Double rainbows

In my garden, when I'm watering the plants I sometimes see a rainbow or two. How did two rainbows appear? Why can't I see three rainbows then, or how can I see three rainbows?
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0answers
9 views

What kind of mirror do i should use for rear projection? [on hold]

i have around 11 inch to make a rear projection for a 94 inch screen. i have tried with a convex mirror (half dome mirror) but the aberration is too blurry on the sides, so i don't know what kind ...
0
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2answers
74 views

Is there a substance that doesn't reflect OR absorb light from the visible light spectrum?

Is there a substance that doesn't reflect or absorb visible light but may reflect light from another spectrum? Is there a theoretical substance that would have these properties? EDIT: Sorry I wasn't ...
5
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2answers
296 views

How would an X-ray mirror work?

I was wondering if light can be reflected how can someone reflect X-ray of what material does it need to be made of and is its design completely different to that of our original mirrors? Does this ...
1
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0answers
22 views

What reflects/scatters sunlight most?

The difference between a white object and a mirror is mainly scattering versus reflection. If we neglect this difference and define the reflectivity by input energy minus transmitted energy minus ...
1
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3answers
76 views

Can light be trapped theoretically?

My question is a little silly I know, but I'm curious to know if a particle of light can be theoretically trapped between two reflective screens. For example once the particle of light has left it's ...
4
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2answers
471 views

Why are most accurate reflective surfaces not white?

Since white is our perception of reflection of light, why are mirrors and other metallic objects that are more grey or silvery capable more reflective than a white object? This is somewhat related: ...
2
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1answer
44 views

Total internal reflection and waveguides

I'm looking at a model of a planar dielectric waveguide along the lines of this picture: For the wave inside the $n_1$ dielectric slab to totally internally reflect $\theta_M$ needs to be smaller ...
1
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1answer
42 views

Anti-reflective coating effect on total internal reflection?

If the surface of prism is coated with an anti-reflective coating, (specifically an index matching, refractive index gradient, or moth-eye structure), and light impinges at a greater than critical ...
5
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0answers
87 views

The physics behind Google Glass' “prism”

In writing a bachelor's thesis about applicable use cases for Google Glass in retail I also strive to explain the physics behind Glass' optics. So far I've come to the following conclusions: Glass ...
0
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1answer
22 views

Compute impulse response of a cavity for sound waves

Given a (closed or not) surface and a point emitting a spherical sound wave, how can I calculate the wave amplitude in any point of space, considering reflections on this surface ? The idea is to ...
0
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2answers
32 views

Bragg diffraction and lattice planes

Crystalline substances show, for certain sharply defined wavelength and incident directions, very sharp peaks of scattered X-ray radiation. From the illustration below we see that we get constructive ...
0
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1answer
45 views

Does sign convention in geometric optics fail to explain the cases of image formation by virtual objects?

Here is an example of Cassegrain telescope: Parallel rays from a distant object get reflected by the concave mirror forming an image at its focus behind the convex mirror. This image acts as a virtual ...
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2answers
310 views

QM: why is reflection of a photon not a measurement?

Many experiments with entangled photons are sending them through different glass fiber cables (e.g. in opposite directions for spatial separation). The photons will inevitably be reflected many times ...
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2answers
39 views

Surfaces that refract, but do not reflect

I know there exists surfaces that only reflect light (mirrors), but are there surfaces that only refract light? If so, how does that happen?
0
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2answers
51 views

Image formation at surface of water

Consider a lake full of water which has an object immersed in it. Now, if an observer was at the surface at a sufficient distance so that the light ray from the object is internally reflected, should ...
6
votes
3answers
818 views

reflection at intersection of 2 mirrors

Consider 2 mirrors which intersect at an angle. If we draw a light ray intersecting the mirrors at their point of intersection, how will it reflect? What will be the normal at that point?
1
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2answers
47 views

Transmission of waves

How do you know if a wave will transmit when it hits a media boundary? Will a portion of the wave always be transmitted when a wave hits a media boundary? My textbook says part of the wave will be ...
3
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1answer
45 views

Differences between absorption, transparency, reflection, and emission

Can someone help me conceptualize the differences between a photon's involvement with absorption, transparency, reflection, and emission? To be more specific, my current understanding of the matter ...
0
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2answers
67 views

How can opaque black object occur?

I know the fact that a material appeared as black when all wavelength photons were absorbed. I also know that opaque object is the result of reflection and scattering of light wave. Is it right? ...
4
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3answers
98 views

Make air reflect light

Is there any way in which air can be made to reflect light? By making air denser or by any other way? The task is to project images in air...
3
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1answer
58 views

Why does silver have such a strong UV resonance compared to other metals?

Related: Why did high quality mirrors use aluminum coatings instead of silver? After reading Chris White’s and LDC3’s comments in the above related link, it got me wondering about silver’s atomic ...
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6answers
2k views

Why did high quality mirrors use aluminum coatings instead of silver?

I have two questions on mirrors. I’ve read that in the past quality mirrors were coated with silver but that today vacuum evaporated coatings of aluminum are the accepted standard. When I look at ...
1
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1answer
55 views

What's best shape for linear concentrated solar panel? [closed]

I found 3 shapes which are suitable for concentrated solar panel. 1. Semicircle - first thing that comes to ones mind. It's a simple shape, the position of the focal point is obvious. 2. Parabolic ...
0
votes
1answer
41 views

Electromagnetic wave in a medium with $\sigma \ne 0$ [closed]

I want to prove that the reflectancy of an Electromagnetic wave in a medium with $\sigma$ $\ne$ 0 is: \begin{align*} R_{\|}=R_{\perp}=\frac{(n-1)^2+k^2}{(n+1)^2+k^2} \end{align*} any advice, please? ...
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1answer
33 views

Reflection vs indices of refraction [closed]

A magician during a show makes a glass lens with refractive index 1.47 disappear in a trough of liquid. What is the refractive index of the liquid? Could anyone please demonstrate with a ray diagram?
1
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1answer
24 views

Reflection Probability for Different Potentials - Quantum Mechanics

My question is above. Firstly, I don't actually know whether it is true or not (!). Secondly, if I were to try to prove it, then I have very little idea how to. The potential steps that I have ...
1
vote
1answer
24 views

How does porous anti-reflection coating work?

We know ideally that if we stick a coating of thickness $d = \frac{\lambda}{4}$ with refractive index $n_{coat} = \sqrt{n_{air}n_{glass}} \approx 1.2$ there would be no reflected wave. But it's hard ...
1
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1answer
34 views

Reflections in a double-glazed window

Recently I observed reflections in a double-glazed window. I wondered that the double reflections were not the same if I changed my point of view. For example the two images of a candle would overlap ...
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7answers
2k views

Why do solar panels not have focusing mirrors?

Most of the solar panels that I have seen do not have any mirrors, etc., but usually solar cookers have mirrors. What is the reason for solar panels not having focusing mirrors?
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votes
1answer
32 views

Sharpest camera shoot within a mirror [closed]

In order to take the sharpest camera shoot from the reflected object image in the mirror, the camera should be placed $x\,m$ farther from the reflected image object. How can I determine $x$ ?
0
votes
2answers
50 views

Wind bouncing off surfaces

What are the physics of wind (or any gas flow really) bouncing off surfaces? If a wind hits a wall directly (in a 90 degree angle) does any of it bounce back? Are there any similarities with, say, ...
0
votes
1answer
48 views

Given two surfaces, one that absorbs light and the other that reflects it, will there be a signficant temperature difference?

My likely wrong understanding of light is this: By some way the molecules are structured, a photon hits an atom or a structure, is absorbed, then re-emitted and it's that photon wavelength that I see ...
3
votes
1answer
63 views

Why do we see the sun's light color different from the moon's light color?

Why do we see the color of the sun's light as red or orange, while we see the moon's light as white, although it's reflected from the sun?
-2
votes
1answer
36 views

Evaluating angle of refraction [closed]

Can someone show me how to evaluate the angle of refraction for white light where the angle of incidence is 30 degrees if medium A is air and medium B is water. The answer is 22 degrees. I don't know ...
4
votes
2answers
91 views

Is a Perfect/Lossless Mirror possible?

In traditional mirrors, some of the input light is absorbed by atoms in the mirrors surface and are 'lost' as heat, degrading the quality of the reflected image. Could this loss be compensated by an ...
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0answers
22 views

size of an image formed by a concave mirror

a short linear object of length b lies along the axis of a concave mirror of focal length f at a distance u from the mirror.what is the size of the image? what i have done so far: since the ...
8
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1answer
1k views

Would the inside of a black hole be like a giant mirror?

As any light reflected or emitted from objects inside a black hole (if it is possible to be there) does not leave the event horizon and comes back inside, would it be like seeing yourself? What I ...
1
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1answer
28 views

Converging mirrors and the transition between inverted and non-inverted images

I was talking with a friend recently about concave mirrors, which frequently invert the reflected image - I think we were playing with a spoon. I raised the question, if you had a mirror whose shape ...
0
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2answers
38 views

Light absorbs and Color [closed]

I'm curious about how the material absorb the light and reflect the light back as colors in a sense of Quantum Mechanics (Quantum Electro Dynamics) Does Hadron related to the absorbs of photon ? or ...
2
votes
2answers
77 views

Anodized aluminium reflectivity at 10.6 um

I wonder how I can model anodized aluminium reflectivity in ray tracing-based optical simulation. I know that the parts my company is using are anodized to get covered with a ~20 um (as specified) ...
10
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2answers
347 views

a wierd image of sun

Have you ever notice the sunset's image in the sea? It's like long light path to the end of the horizon! I've attached a sample of this: How can we explain this? I know that it can happen even in ...
1
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0answers
35 views

Beamsplitter and Dielectric Mirror

Among two optical components. One is a Nd:YAG Laser 50/50 Beamsplitter and the second one is a Dielectric Mirror see pictures. Both of them almost looks like the same. If the specification is not ...
0
votes
2answers
71 views

Layer thickness measurement

I am interested to measure the thickness of the coating on a mirror (e.g. in the picture below). What are the available and best way of measuring it? What will be the solution in case of multiple ...
1
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0answers
82 views

What is the effect of total internal reflection on polarized light [closed]

Total Internal Reflection causes phase change of a light beam. I searched for effect on a polarized light beam by Total Internal Reflection but could not find much. I am assuming polarization does not ...
6
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2answers
255 views

About photons and mirrors

If a photon hits a 'perfect' mirror (with no environment interference) would the mirror move a bit?
0
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0answers
72 views

Difference between the increase in optical path due to refraction and that due to reflection

If we place two glass plates of refractive index n and each having thickness t,on the way of a light ray the increase in optical path becomes (S2P-S1P)=2(n-1)t due to refraction through them,and the ...
0
votes
2answers
52 views

How is the image in a mirror created? Are there infinitely many light rays?

How is the image in a mirror created? Are there infinitely many light rays? My motivation for the question is from image processing. We work with images as discrete 2D functions, as matrices. Spatial ...
14
votes
2answers
549 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. ...
0
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0answers
20 views

Transmissivity of Liquid Crystals in the near-infrared range

The gist of my query is in the title. I have been searching for papers and studies that could provide transmission curves (in nematic liquid crystals) across the visible to near-IR range (or from ...