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0
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2answers
179 views

Optical path difference

I have question about calculating optical path difference. $$\Delta L = \mathrm{(BC+CD)}\cdot n_2 - \textrm{BF}\cdot n_1$$ - why calculating path difference here we are subtracting $\mathrm{BF}$ ...
42
votes
5answers
3k views

What causes this pattern of sunlight reflected off a table leg?

My friend noticed an interference-like pattern around the table leg. However, we do know that interference patterns of sunlight produces rainbow colours. What seems to be happening here?
0
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0answers
28 views

Light of planets and natural sattelites [closed]

I have been getting stuck while solving and imagining the following problem: According to Plank's quantum theory "Energy radiated or absorbed by a body is not continuous but discontinuous in the form ...
0
votes
2answers
371 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 ...
2
votes
3answers
271 views

What makes a rainbow happen?

A rainbow is formed when a raindrop refracts light, but why then does the whole sky not become a huge rainbow when it rains? Would the light not be dispersed into ordinary white light? What causes it ...
0
votes
0answers
15 views

How do laser triangulation sensor reflection obeys law of reflection?

I find it hard to understand how laser triangulation sensor work considering this image The laser beam form the angle of $90^o$ with the surface so how can the reflection beam form the different ...
0
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0answers
20 views

Sun light collimation

Is it possible to make sun light collimated in such a way, to increase energy density and keep it more less parallel? like on the Earth we have intensity of sun approximately 1300 watt/m2. If we use ...
0
votes
1answer
29 views

Near perfect reflectors and LASERs

What would happen in a hypothetical scenario in which a LASER strikes a near perfect reflector (like the ones made by Jason Valentine at Vanderbilt, which reflect 99.7% of visible infrared light). I ...
1
vote
1answer
38 views

Magnifying glass as a mirror?

I understand how a magnifying glass works as a convex lens, however I am curious as to how one can explain using it as a mirror. When I observe the reflections off of a magnifying glass, strangely ...
0
votes
1answer
12 views

Conditions imposed in wave reflection and transmission in one dimension

In the study of trasmission and reflection of waves in one dimension I do not understand completely the meaning of the conditions imposed. Consider an impulse $\xi(x,t)$ moving on a rope linked with ...
1
vote
0answers
31 views

What happens if we stand in the centre of a sphere inside covered with as a mirror? [duplicate]

What happens if we stand inside a sphere covered with as a mirror? That is when we are at the centre of a spherical mirror, how the image of us is formed?
3
votes
2answers
75 views

Polarisation by Reflection - oscillation direction

I'm currently studying polarisation by reflection, and have come across two pieces of information from the same source, which I can't seem to understand on how they differ. The oscillation direction ...
1
vote
1answer
50 views

What are the right signs? [closed]

This is a question provided in my book: An object of height $2\ \mathrm{cm}$ is placed at a distance of $2.5f$ from a concave mirror where $f$ is the focal length. Find the height of the image. ...
-1
votes
1answer
24 views

Reflection and angle of refraction

Does the angle of refraction depend on the properties of the material if the angle of the incidence is the same for two different materials? Say I shed light on a surface with angle $ \theta $ and ...
0
votes
1answer
44 views

special relativity mirror experiment

There's an experiment in special relativity that involves a light source and a mirror, both placed in a moving object. It is used to derive the time dilation equation. I'm having serious doubts about ...
4
votes
1answer
45 views

Explain Sun Glare

Above is a picture that I took just before the sun set. Notice the prominent red blob to the left of the sun. Can anyone explain the phenomenon that creates superimposed shapes and blobs in images ...
-1
votes
0answers
19 views

Is It Possible to look at our own past if we find a giant reflecting galaxy as distant as needed for a telescope? [duplicate]

Can a telescope catch light reflected from object distant away so that we see our own planet hundreds/thousands/millions years ago. Another suggestion is that we send the giant mirror as far as needed ...
13
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1answer
782 views

Reflection of light rays

A set of light rays emitted from a point of an orange hits a smooth and flat surface. My question is: The angles of incidence are different, light rays are reflected towards different directions, why ...
0
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2answers
39 views

Polarized light from any suface?

From a textbook I read something like this: "When sunlight is reflected from a horizontal surface, the plane of incidence is vertical, and the reflected light contains a preponderance of light that is ...
0
votes
0answers
13 views

Constructing a chriped dielectric mirror for negative dispersion for ultrashort laser pulses resulting in group velocity delays

I'm currently looking at designing a chirped mirror for a project but I am confused over several aspects. I understand the principle of a chirped mirror in terms of how a laser pulse has a broad set ...
2
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2answers
40 views

How does change in medium affect object distance/image distance?

Say,we have a container filled with a liquid of refractive index $7/5$ upto a height up $H$. There exists a plane glass mirror at the bottom of the container. Now if a fish were placed at a height of ...
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0answers
11 views
2
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2answers
386 views

Law of reflection for a moving mirror

An elementary fact that people learn about mirrors is the law of reflection, that the angle of incidence of a light beam striking the mirror (as measured with respect to a normal) equals the angle of ...
14
votes
3answers
3k views

Is true black possible?

Black is the absence of light because it absorbs light, but when we create black paint or black objects, light is always reflected, either in all directions in matte or smoothly in shiny black ...
1
vote
2answers
124 views

How to calculate reflection profile of a beam shining onto a moving mirror?

I want to build a projector, where a beam of light is shining on to mirrors, placed at different angles, which are spinning fast enough to draw lines. The question is, how to calculate the needed ...
1
vote
3answers
75 views

Why don't E&M fields change orientation after hitting a surface?

In essentially every derivation of the Fresnel equations, the general problem of radiation hitting a surface at a certain angle is broken into two parts (out of which we hope the solution any general ...
1
vote
2answers
41 views

Will the thickness of a material affect the reflection properties

Does a thicker piece of material(lets say metal) reflect wifi signals the same as a thinner piece of material? I realise that thicker materials would block out more at the back, but my question is ...
0
votes
1answer
28 views

Frequency dependence of electromagnetic reflection

I was surprised to see that the Fresnel equations for reflection depends on refractive index and angle of incidence, but they do not depend on frequency. Why is this case? Are they restricted to ...
0
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0answers
5 views

Height of a point in a plane given a measure of luminance

Context Assume a left-hand rule coordinate system and X points right, Y points up, Z points out. I have a camera facing perpendicular to the X-Z plane in the negative Y direction. I have 4 ...
0
votes
0answers
20 views

Mirror shake emulation for the light

Is there any way to simulate mirror shaking? Final goal is to make send light beam to the mirror and get reflected beam the same, as it happens if mirror is vibrating. Mechanical vibration is limited ...
3
votes
1answer
26 views

Is perfectly diffuse reflection entropy maximizing?

Suppose that I shine light on a surface and none of it will be absorbed or transmitted, and the spectrum doesn't change (so that all that's left to determine is the power reflected from the surface as ...
0
votes
1answer
60 views

What is the difference between a white object and a mirror in terms of heat absorption?

Will a white object be cooler than a mirror when exposed to direct sunlight? Or will it be the other way around? If mirrors bounce all visible light and some of the other elements of electromagnetic ...
0
votes
1answer
29 views

Blue light is reflected, red is not. What happens to other visible/non-visible light?

The problem says: The certain film on the glass reflects blue light of wavelength 480nm, but does not reflect any red light of wavelength 640nm. 1) If we say that it reflects blue light but no red ...
0
votes
1answer
53 views

Why does phase of a wave change after reflecting from a denser medium?

Why does phase of a wave change when reflected from a denser medium, but no change takes place in phase during transmission?
0
votes
1answer
26 views

Reflection in Finite Square Wells

For a Finite Square Well where we have a wavefunction $\psi(x)$ which is an energy eigenfunction with eigenvalue $E = 2V_0$ in the following potential: $V(x) = \begin{array}{ll} 6V_0 ...
2
votes
1answer
88 views

How does QED explain reflection? [duplicate]

By reflection of photons from a mirror, the mirror must get an impulse of 2p=h/pi.l for every photon. This means that the mirror receives kinetic energy. But the photon has the energy it has before ...
3
votes
1answer
112 views

Why do shiny surfaces reflect more light than other surfaces?

I'm an A-level student and I love learning new things in physics. A new concept that I learnt says that the reflection is due to the scattering of light by electrons in the material. I've got my ...
38
votes
11answers
13k views

Why don't we hear sound reflecting from buildings, mirrors, etcetera?

We can see buildings, doors, cars etc. as light falls on it gets reflected to us. but why doesn't the same thing happen with sound? I mean why don't we hear sound reflecting that much?
15
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1answer
916 views

Why is everything not transparent? [duplicate]

There is a related question on this site here: Why glass is transparent? Which explains that glass is transparent because the atoms in glass have very large energy differences between energy levels ...
0
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0answers
29 views

How can air pollution contribute towards light pollution?

I was just wondering if air pollutants such as soot, could reflect light into the night sky, and thus be a potential source of light pollution. If that's true, can you please suggest any other air ...
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vote
1answer
216 views

Explanation for Refraction of light (change of angle) and Reflection

Refraction: I want a qualitative Quantum Mechanical explanation of why do we see light rays -in the classical picture- bend when light goes from one medium to another. I read that it is due to ...
5
votes
4answers
958 views

Wave reflection and open end boundary condition intuition

I need to understand one seemingly simple thing in wave mechanics, so any help is much appreciated! When a pulse on a string travels to the right toward an open end(like a massless ring that is free ...
9
votes
2answers
88 views

Why is reflected light polarised?

Why is reflected light polarised? I have learnt about Brewster's angle, and how at a particular angle all light reflected is polarised, but do not understand why. Is this something that could be ...
2
votes
0answers
68 views

What happens to Newton's Third Law during the reflection of a pulse from a free end?

Well, it is known that a pulse gets inverted when it gets reflected from a fixed support while the polarity of the pulse remains same when the incident pulse gets reflected from a free end. However, ...
28
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6answers
7k 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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0answers
37 views

Why do different color materal differ temperature in the same sunlight?

I have a blue, red, and green cup and put a thermometer in each. Of the 3 the blue cup had the coldest temperature inside, then green, then red. I understand there may be differences in the ...
10
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3answers
779 views

Using a black hole as a mirror?

http://www.youtube.com/watch?v=ENd8Sz0AFOk The YouTube video is a good example how the gravity of this merging binary black holes bend light around themselves.
1
vote
1answer
37 views

Fresnel equations for perpendicular angle of entry [closed]

In many text books one finds for the fresnel coefficients for light perpendicular to the surface: $$r = \dfrac{n_1 - n_2}{n_1 + n_2}\quad\text{and} \quad t = \dfrac{2n_1}{n_1 + n_2}.$$ When I try to ...
2
votes
1answer
40 views

Number of photons through glass [closed]

I am getting mixed information on the total photon count involved with light transmission through glass. I'm not looking for percentages and I don't have equipment to count photons. For simplicity ...
0
votes
0answers
21 views

On which factors does reflectance depend?

For my college physics project I'm planning to measure the change in reflectance of an object with respect to a factor (temperature, current going through, etc., not angle of incident, wavelength, ...