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2
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1answer
72 views

How does a photon 'know' when to reflect in case of refraction? [closed]

In thin-film interference and in glass fibers refraction is involved. Depending on the angle of which a light ray enters the material it will be reflected or transmitted. The refraction depends on the ...
14
votes
2answers
1k views

The speed of light upon reflection [duplicate]

(NOTE: I am an 8th grader, so I may not be capable of perfectly elaborating my point by scientific measures. Also, English is not my first language) I have read that the speed of light is constant, ...
0
votes
0answers
31 views

How thin can a mirror be? [duplicate]

What affects the reflective properties of a material? From everyday experience, metals are good at reflecting light. How thick should be a mirror to reflect most sun light energy? For the case with ...
0
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0answers
12 views

Projection of 3d object to an optical 2d matrix

I want this projection explained. I can explain it like you have a rectangular "screen" of paper that you translate along its normal towards the 3-d line. If screen is parallel to the line, the hole ...
-1
votes
1answer
19 views

Standard green glass reflection and absorption rates by wavelength

Is there any exact data on reflection and absorption rates based on wavelength for the common green glass materials ? I know the rate itself is dependent of the angle, the exact composition of the ...
0
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0answers
18 views

What do we mean by angle of incident equals angle of reflection? [duplicate]

When we incident light on something the electrons of that stuff absorbs the energy goes to higher state and then come back to ground state and emits radiation so my question is what is happening at ...
2
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0answers
26 views

What makes some materials more reflective that others? (atomic level)

I am an A-Level student doing some research into beryllium. I have found it is highly reflective due to its free electrons re-emmitting EM waves. One thing i am stuck on however, is why beryllium is ...
4
votes
1answer
75 views

At what direction does a ray reflect at a 90 degrees corner?

Say we pointed a laser that is projected into a $90^{\circ}$corner of a mirror made by perpedicular walls. I know that you cant use tangent since a derivative of boundary of mirror would not exist ...
1
vote
1answer
25 views

Reflectivity of Metallic surfaces

Can someone please point me to an academically verified web resource/page that tabulates the Reflectivity of various metallic surfaces like gold, silver , aluminium etc? I have found a list on ...
0
votes
2answers
62 views

Why haven't we created a material that is completely invisible to the human eye? [closed]

From what I understand, If something was not reflecting photons in any direction, you could then see through it. If photons transfer into thermal energy could something very cold help? Could the ...
4
votes
2answers
115 views

Why is it easier to get sunburnt in the water? [duplicate]

I went today to the swimming pool and I remembered that when I was younger my mom used to tell me to be careful because you get sunburnt much more easily in the water than in the ground. I never gave ...
0
votes
2answers
85 views

Solar Sail Questions

I'm just looking for a good (better) analogy. How do massless photons put pressure on a surface especially when it's a mirror? Using the analogy of the wind (atmosphere) on a sail breaks down when I ...
1
vote
1answer
42 views

Question about Fermat's principle

Why when deriving the law of reflection from Fermat's principle of least time do I set $dL/dx = 0$? I am a 12 grade student with a little notions of maxima and mimima in one variable calculus.
0
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0answers
29 views

Can refraction be thought of as a special type of reflection?

So, I know the difference between refraction and reflection but I've been wondering today if maybe refraction could be thought of as a special type of reflection with a very obtuse angle. Reflection ...
0
votes
0answers
12 views

Reflection coefficient of transition coaxial and wave guide

Suppose you have a 1 GHz generator connected to a wave guide with a coaxial cable with a characteristic impedance of $Z_c =45 \Omega$. The wave guide is connected to the system which has a reflection ...
1
vote
1answer
52 views

why can't we see our image on a simple brick wall?

We can see our image in a mirror due to the reflection of light. We also know that a red color brick wall also reflects light. So, why can't we see our image there?
1
vote
1answer
30 views

What causes the bright glow on the edge of fiber optics and translucent sheets?

http://imgur.com/8PHxy6z On top of the picture, we have a number of translucent sheets. The edge of the sheets seems to glow compared to the rest of the body; why is this? On the bottom of the ...
1
vote
0answers
66 views

Time involved in reflection

Consider light bouncing back and forth between two ideal front surfaced mirrors. How long does the process of reflection (i.e., absorption and re-emission) take?
0
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1answer
46 views

Proving that angle of incidence over angle of reflection is constant in Snell's Law

First let me state what I think I know: Snell's Law states that $\frac{sin(i)}{sin(r)} = \frac{v_1}{v_2}= \frac{\lambda_1}{\lambda_2}= \frac{n_2}{n_1}$ where i is the angle of incidense and r is the ...
0
votes
1answer
40 views

On parabolic concave mirror in car flashlights

Sorry for the seemingly silly question but what's the advantage of having a concave mirror in car flashlight? I understand how the physics works but I just don't get what the advantage of having this ...
0
votes
1answer
35 views

WHY are reflections stronger at an angle acording to the Fresnel equation?

When looking straight at a glass surface you can mostly see through it, but if you look at it at an angle it becomes more and more like a mirror surface. This is described by the Fresnel equation, or ...
0
votes
1answer
63 views

What is the difference between reflection and total internal reflection (TIR)?

I look at what TIR is and then what reflection is - when the angle of incidence and the angle of election are the same. And TIR is when the angle of incidence is greater than the critical angle. TIR ...
0
votes
0answers
29 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
votes
0answers
39 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
31 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 ...
2
votes
1answer
56 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
14 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?
-1
votes
1answer
27 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
49 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 ...
13
votes
1answer
792 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 ...
1
vote
0answers
15 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
votes
2answers
47 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 ...
1
vote
0answers
11 views

When light reflects from a medium of lower index of reflection to a medium of higher index of refraction, why does the light undergo a phase shift? [duplicate]

I learned in my physics class that there is a phase shift when light reflects off a low $n$ from a higher $n$, but never got the explanation.
1
vote
3answers
81 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
62 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
0answers
12 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 ...
0
votes
1answer
45 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 ...
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
100 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
38 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 ...
4
votes
1answer
53 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 of ...
0
votes
1answer
74 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
27 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
115 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
159 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 ...
0
votes
0answers
31 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 ...
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?
2
votes
0answers
75 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, ...