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7
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3answers
249 views
+50

Does radiation force depend on group velocity or on phase velocity?

What is the radiation force $F$ due to a beam of photons of power $P$ undergoing perfect reflection? Is it $$a) F = 2 P / c$$ or $$b) F = 2 P / v_g$$ where $v_g$ is the group velocity ? Note that ...
0
votes
1answer
44 views

Do parallel rays reflecting at a mirror not intersect at one point? [on hold]

Let's take a concave mirror with $CP$ as its principal axis. Let's assume that a parallel ray $p$ to $CP$ reflects at $A$ to pass through the focal point $F$. Then, $\angle CAF=\angle ACF$, which ...
2
votes
1answer
89 views

Probability current in scattering problems

This is a section from Wikipedia: In regions where a step potential or potential barrier occurs, the probability current is related to the transmission and reflection coefficients, respectively ...
0
votes
2answers
216 views

Light-matter interaction and an object's appearance

I am taking a course in Computer Graphics, and the teacher said we could put materials in there main categories: mirror like glossy or specular diffuse He suggested that the law of reflection is ...
4
votes
5answers
202 views

What about a surface determines its color?

Light falls on a surface. Some wavelengths get absorbed. The other are reflected. The reflected ones are the colors that we perceive to be of the surface. What is the property that determines, what ...
2
votes
1answer
34 views

Conserved quantity corresponding to reflection symmetry

I know about Noether's theorem, but I don't actually know how to use it myself. Suppose our universe were symmetric with respect to reflections about planes. What conserved quantity would then exist ...
0
votes
0answers
27 views

How to achieve transmission only at normal incidence?

Is there any material that only transmits normally incident radiation and reflects it when it's incident at any other angle? Or any way to achieve such an effect? For example, a mirror that if you ...
0
votes
1answer
31 views

Geometry confusion with incident E field

My geometry is very rusty and I'm having trouble understanding why for the incident E field the X component is multiplied by cos and the -Z component is multiplied by sin instead of the other way ...
4
votes
0answers
23 views

3D glasses and reflection/polarisation [duplicate]

Hi all, Tonight I'm going to see a 3D film so I thought I'd check whether I had any old 3D glasses around the house. Found a pair of "RealD" glasses. Anyhow, I assume that the glasses use some ...
201
votes
19answers
69k views

A mirror flips left and right, but not up and down

Why is it that when you look in the mirror left and right directions appear flipped, but not the up and down?
20
votes
8answers
7k 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?
0
votes
2answers
170 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
votes
1answer
57 views

Why mirrors form image and others don't?

In the case of mirror, I understand how a image is formed, If I replace plane mirror by wood or some other opaque material in the above image and position of object(bottle) and eye remain the same , ...
3
votes
3answers
784 views

During reflection does the emitted photon have same properties?

When light (photon) is reflected the the original photon is absorbed by an electron and then emitted again. Does this "new" photon have the same wavelength, frequency etc. as the original?
1
vote
2answers
59 views

reflection of light and the uncertainty principle

I've heard that light reflects the same angle that it falls and so if we know the position of photon (the spot where it hits the surface) and the direction of where it shall go - that's violation of ...
0
votes
0answers
24 views

About the property of the mirror [duplicate]

It is actually said that left appears to be right and right appears to be left in a mirror. But when I stood in front of the mirror and raised my right hand, then according to this property my mirror ...
2
votes
0answers
19 views

statistical property of light reflected from a coarse mirror

This is a problem comes up in my study in correlation reflectometry. I'm wondering if there is a straight-forward way to interpret the phase and amplitude of the reflected light from a perturbed ...
0
votes
1answer
29 views

combination of mirror and lens [closed]

a convex lens forms a real image of a point object at a distance of 50 cm from convex lens. a concave lens is placed 10 cm behind convex lens on image side. on placing a plane mirror on the image side ...
2
votes
3answers
103 views

Violation of conservation of energy?

Imagine a perfectly spherical mirror with 100% reflection. Imagine a point source of light in the center. The point source keeps radiating light. Will the light undergo destructive interference ...
6
votes
3answers
947 views

reflection at intersection of two 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
vote
2answers
157 views

Basic rule for diffraction

I'm a high school student. I still don't understand the reflection, diffraction and refraction of light. It seems to me that in concept of quantum physics, reflection is just a process of object ...
10
votes
2answers
441 views

Why does sunset over a body of water cause a path of light stretching towards the horizon?

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 ...
0
votes
0answers
21 views

Why does a circle of light form around a wire when a laser is pointed at it? [duplicate]

Referencing this video: https://www.youtube.com/watch?v=9Q_4SNbpBfo Why does a circle of light form? I've seen previous Phys.SE posts on this topic relating the answer to reflection, but I have ...
5
votes
1answer
60 views

Long, blurry reflections in wet road [duplicate]

When driving on a wet highway at night, any surface emitting or reflecting light will have a reflection right under it that is blurry and seems to stretch to infinity. This is not exactly what I am ...
0
votes
2answers
802 views

Colors in the secondary rainbow reverse of that in the primary rainbow

Why the colors of Secondary rainbow is reverse of that in the color in the Primary rainbow? What can be the possible reason among the following options Because it is formed by one internal ...
22
votes
5answers
5k views

Does a well-lit mirror weigh more than an unlit mirror?

If you weighed a mirror in a room with no light, and then weighed a mirror in a well lit room so that the mirror reflects light, would the weight be different?
1
vote
1answer
30 views

Polarization and Reflection [duplicate]

The polarization is a property of waves that can oscillate with more than one orientation. Given this, when the light is reflected from a surface, does the reflection change the property/orientation ...
0
votes
0answers
14 views

Is image scale the same as focal length?

I am supposed to show using a diagram how image scale is related to focal length. But my formula for image scale is $$\text{image scale} = \frac{y}{\theta} = F$$ where $y$ is the image size on the ...
0
votes
1answer
41 views

If I observe a planet because of reflected sun-light, how does the radiant flux vary with distance?

I wish to figure out how the flux of the sun's reflected light from a planet varies with distance, so assume an observer is on the sun, looking at a planet, and the light originating from the planet ...
1
vote
4answers
251 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?
0
votes
0answers
24 views

Why the underside of an object isn't a different colour after light reflects off a different coloured surface

If you were to place a blue plate in front of a green background and shine a light at the blue plate. The light that hits the blue plate would reflect the blue wavelength and when the reflected ...
2
votes
3answers
178 views

What really makes a rainbow happen?

Yes, 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 ...
1
vote
0answers
25 views

Help with finding an equation to work out the length of cable required to produce loss of colour on an analogue video signal

When I briefly taught Broadcast Engineering I set up an experiment in order to demonstrate the effect of signal reflections along coaxial cable on an analogue PAL waveform. It involved getting the ...
3
votes
1answer
28 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 ...
12
votes
2answers
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 ...
3
votes
0answers
33 views

What are the limitations on the Paraxial Approximation?

What my physics book referred to as the paraxial approximation derived to be thus: $$\frac{1}{s}+\frac{1}{s'}=\frac{2}{R}$$ as a way of showing that in a concave spherical mirror, all reflected rays ...
0
votes
0answers
41 views

hiding joint lines of plain mirrors

For some experiment I took two rectangular pieces of front surface mirrors, and joined it at 30 degree. However, the joint line is visible clearly, how do I hide it ? I guess I need to apply some ...
1
vote
1answer
54 views

Can a one-way mirror effect be reversed?

I understand to get the effect of the one-way, one side needs to have light to produce the mirror, leaving the darkened side with the ability to see through. I would like to know if there is a way to ...
1
vote
1answer
38 views

Question on Minimum Glare from Reflected Sunlight

I'm studying for the IB Physics HL exam, and I came across a question neither my physics teacher or I can solve. It has a diagram like so: http://imgur.com/hYssY5o The text of the question is this: A ...
2
votes
0answers
111 views

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 ...
0
votes
2answers
39 views

Calculate required power output for a laser

How to calculate power rating required for a laser in order to produce a dot at a specific distance after reflection? For example, the laser is 10cm from the mirror, at an angel of 30 degrees it ...
2
votes
1answer
78 views

Increase contrast on the image taken by CCD camera

I project a pattern on a reflecting object and I capture the reflected pattern (reflected via the object) using a CCD camera. However, the reflected pattern has a very low contrast (due to volume ...
0
votes
1answer
61 views

Optical system for cloning an image of a light source?

I need to create an optical system for cloning an image of a light source to human eyes. Is there a correct solution(design) for this problem. Reflectivity of the mirrors must be equal. Because ...
1
vote
2answers
49 views

How would a plane hitting a ball move (opposite of Pong)?

When a moving ball hits a stationary plane at an angle of incidence to the normal, it bounces away at the same angle (the angle of reflection), which is commonly understood. My question is 1) What ...
0
votes
1answer
50 views

Would we see the past if we look to a mirror 1 light year away? [duplicate]

What would we see if we place a mirror 1 light year away? Would we see the present or the past?
3
votes
1answer
55 views

Wave interference on window film coating

"The windows in an office tower are coated with a film to minimize reflected light of wavelength 550 nm. If the glass has an index of refraction of 1.52 and the film coating has an index of refraction ...
0
votes
1answer
25 views

Distinguishing between perfect rigid mirror and symmetrical universe

I have a relatively bizarre question which I'm not even fits into the category of mainstream physics, but here I go anyway. I want to consider two hypothetical situations. Then I want to see if there ...
16
votes
5answers
17k views

Phase shift of 180 degrees on reflection from optically denser medium

Can anyone please provide an intuitive explanation of why phase shift of 180 degrees occurs in the Electric Field of a EM wave,when reflected from an optically denser medium? I tried searching for it ...
0
votes
2answers
67 views

Phase change on reflection only 0 and $\pi$ allowed

We know that when a wave on a string is reflected from a hard boundary, the phase change is $\pi$, and from a soft boundary, the change is 0. My question is: this two conditions (hard and soft ...
1
vote
0answers
16 views

Phase change by reflection [duplicate]

Let's consider a light ray falling on a cuboid made of glass at the angle $\alpha$. Then there will be a reflected ray $A$. The ray will also refract. Let the refracted ray be $B$. Ray $B$ will be ...