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2
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3answers
79 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 ...
0
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0answers
17 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
43 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 ...
23
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
26 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
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0answers
13 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
35 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 ...
0
votes
0answers
21 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 ...
1
vote
0answers
23 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
20 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
29 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 ...
1
vote
1answer
28 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 ...
1
vote
1answer
47 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 ...
0
votes
0answers
33 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 ...
0
votes
2answers
34 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 ...
0
votes
1answer
52 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 ...
0
votes
1answer
47 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?
1
vote
2answers
47 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 ...
3
votes
1answer
30 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
22 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 ...
1
vote
0answers
15 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 ...
1
vote
0answers
25 views

What is the “Obscuration Factor (OBF)”?

In a paper I am reading for my master thesis I came across this "obscuration factor (OBF)". The authors indicate that it is a measurement of the average intensity of reflection. They do not give a ...
1
vote
1answer
37 views

Surfaces that reflect UV rays

I've been trying to research what surfaces reflect UV rays for the past day but it's been difficult coming up with definitive answers. So far what I've found is that surfaces that reflect visible ...
4
votes
1answer
49 views

What causes these rainbow effects using a polarizing filter on an airplane?

I know that light reflected from a surface at 45° is polarized and that for a similar reason skylight arriving from a direction orthogonal to the sun is polarized too. Photographers make use of this ...
0
votes
0answers
36 views

Would you be able to see yourself in a mirror in front of you as you two are in a room traveling at the speed of light? [duplicate]

Veritasium talked about this in one video. If you are in a room or a train, plane, car or whatever just a closed space traveling at the speed of light and you put a mirror in front of you, could you ...
0
votes
1answer
33 views

Metal Refractive index

I'm working on Fresnel equation for calculation of reflection of a light (532 nm) on Iron. I've got a question: Is metals refractive index always a real number or it can be a complex number?
1
vote
2answers
88 views

Why does the light instantly disappear when we switch off the source?

For example i take a box which is completely covered by the most perfect mirrors possible inside and inside that box i have a bulb whose bulb holder is also covered with the most perfect mirrors ...
2
votes
0answers
31 views

Model of scattering in wet things

You know that clothes and some surfaces become darker when wet (covered in an earlier question: why wet is dark?), because of the disordered reflections or of the refractive index of water or ...
0
votes
1answer
36 views

What is the phenomena where an object is repeated in a glass surface?

I don't understand why this happens. Is the image being repeated because the light is being bounced back and forth on the multifaceted surface?
2
votes
1answer
74 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
1answer
55 views

Light absorption for different liquid

when I was working on a cylindrical glassy bottle that filled with water, I found that the initial light intensity is less than the final light intensity. (It's clear but I experiment this) This is ...
0
votes
1answer
28 views

Why does light reflected on water tends to 'smear' in the vertical direction? [duplicate]

I have noticed that in city lights reflected on the water are very often smeared more in the vertical direction (relative to the reflecting plane I presume), than in the horizontal direction. See, for ...
1
vote
1answer
39 views

Can a virtual image created by a mirror have position in front of the mirror?

I dont think so, because then the rays will intersect and the image will be real. Please let me know if you know a case in which a virtual image is formed in front of the mirror.
4
votes
2answers
72 views

Can gravitational waves resonate?

Can gravitational waves resonate? - Perhaps by creating standing wave interference in a cavity? Could that feasibly happen either in nature or by engineering?
-2
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2answers
30 views

Ideal mirror properties [duplicate]

Suppose there is sphere which is completely made of ideal mirror. What if a light particle is induced in it by a source of light? Does the light particle remains there by bouncing or disappear after ...
1
vote
2answers
66 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
0answers
36 views

Explanation for strange atmospheric phenomenon

OK, I've seen this strange thing in the sky sometimes. Not all that often, but sometimes. It actually happened tonight. On most nights, at say 9 P.M. it is dark. There might be stars, moon, ...
1
vote
1answer
150 views

Are reflection and transmission coefficents real or complex?

Is it common practice to give reflection and transmission coefficients as the ratio of the respective waves with respect to the incident wave when written in complex form or real form? I have seen ...
0
votes
1answer
35 views

Can an aluminized blanket hide a person from thermal cameras? [duplicate]

Well, if the person is wrapped tightly I expect the answer is "no", but could an aluminized loose "cloak" hide a person from thermal imaging cameras by reflecting the cold surroundings? Or, if the ...
0
votes
0answers
60 views

Reflection and refraction of light [duplicate]

When a light ray strikes an interface a part of it gets reflected, a part of it gets absorbed while another part gets refracted. Why does light reflect? Why does it refract?
1
vote
0answers
42 views

Maximum laser power that mirror can handle?

Can I use standard mirrors used for lasers used for laser shows to build some laser that has higher power and is able to burn materials? What are power and power density limitations that cannot be ...
1
vote
2answers
79 views

Why does the thought experiment of a photon bouncing of a mirror imply anything for other objects?

Okay, so I am reading a book, "The Elegant Universe" by Brian Greene, which talks about motion and its effect on time. Greene makes the point that time changes with motion by saying that if you have ...
0
votes
0answers
26 views

absorption and reflection of sound on molecular level

Can someone explain the reflection and absorption of sound on the molecular level? What really is reflection? Why porous and soft material absorbs sound? What's the definition of soft in terms of ...
1
vote
0answers
52 views

What is the total reflectivity/transmissivity of a pack of a semi-transparent glass sheets [closed]

Consider a pack of $N$ layered semi-transparent parallel glass sheets (like a 'cake'), each having the reflectivity coefficient and thickness $(r_k, d_k)$ for $k=1 \dots N$. Consider a light beam of ...
2
votes
1answer
54 views

light falling on a completely reflecting friction less mirror

If you had a perfectly reflective mirror whose face was perpendicular to the ground and was kept on a friction less track on the ground, and you shined a flashlight on it, what would happen? Would ...
5
votes
1answer
648 views

Laser, wire, and a circle of light

So, when I point a laser at a piece of wire (pointed at a specific angle), a circle of light appears on a wall behind it (see image below). I am trying to see why this happens and if there are any ...
3
votes
3answers
182 views

How to understand this symmetry in the wavefunctions of a diatomic molecule?

In Wikipedia (and elsewhere), a particular symmetry of the quantum system of a diatomic molecule is mentioned: symmetry under reflection along a plane containing the internuclear axis. The ...
4
votes
3answers
212 views

How to arrange mirrors so I can't see myself?

If I wanted to surround myself with mirrors how would I need to arrange them so that if I stood in the middle of them I couldn't see myself in any reflection? For simplicity let's just say we only ...
0
votes
1answer
94 views

Reflection in a cylindrical mirror

Suppose I have a completely cylindrical surface which is silvered on the inside. I want to know what type of reflection takes place when an object is placed inside the ring. Does infinite reflections ...