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2answers
387 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 ...
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3answers
213 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 $\mathrm{BF}$ ...
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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 ...
4
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1answer
65 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 ...
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0answers
24 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 ...
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1answer
22 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 ...
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2answers
56 views

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

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 ...
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6answers
8k views

Reflection At Speed of Light

I have looked online to no avail. There is two competing answers and I am curious to know which one is right. Someone asked me this question. If you are traveling at the speed of light can you see ...
4
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2answers
90 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 ...
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2answers
83 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 ...
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1answer
39 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.
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0answers
28 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 ...
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0answers
11 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 ...
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0answers
19 views

What characteristics of incident light changes upon reflection

I am searching for various characteristics of incident light that get modified or changed in reflected light compared to incident light. Light could be monochrome or multi-chrome. I am looking into ...
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1answer
41 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?
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1answer
28 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 ...
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1answer
41 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 ...
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2answers
3k views

Huygens' Principle During Reflection: comparing wavelets from before reflection with wavelets from during reflection

I was recently reviewing geometric optics, during which I read about Huygens' Principle and how it could be used to prove the Law of Reflection from the "light is a wave" viewpoint. I'll quote what I ...
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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?
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1answer
37 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 ...
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1answer
287 views

Should a superconductor act as a perfect mirror?

I have been told that metals are good reflectors because they are good conductors. Since Electric fields in conductors cause the electrons to move until they cancel out the field, there really can't ...
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2answers
129 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 ...
0
votes
1answer
28 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 ...
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1answer
39 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 ...
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5answers
5k views

What happens to light in a perfect reflective sphere?

Let's say you have the ability to shine some light into a perfectly round sphere and the sphere's interior surface was perfectly smooth and reflective and there was no way for the light to escape. If ...
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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?
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3answers
279 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 ...
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0answers
19 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 ...
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0answers
34 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
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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 ...
2
votes
1answer
48 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
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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
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2answers
77 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
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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. ...
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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 ...
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1answer
46 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
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1answer
50 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 ...
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1answer
787 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
41 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 ...
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0answers
14 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 ...
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2answers
44 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
420 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 ...
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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 objects,...
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3answers
77 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 ...
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2answers
52 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
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1answer
41 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
8 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 ...
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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 ...