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Questions tagged [reflection]

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24
votes
4answers
13k views

Explain reflection laws at the atomic level

The "equal angles" law of refection on a flat mirror is a macroscopic phenomenon. To put it in anthropomorphic terms, how do individual photons know the orientation of the mirror so as to bounce off ...
43
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3answers
8k views

How are classical optics phenomena explained in QED (Snell's law)?

How is the following classical optics phenomenon explained in quantum electrodynamics? Reflection and Refraction Are they simply due to photons being absorbed and re-emitted? How do we get to Snell'...
36
votes
6answers
63k views

Phase shift of 180 degrees of transversal wave on reflection from 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 ...
21
votes
8answers
13k views

What happens when a photon hits a mirror?

When a photon of light hits a mirror does the exact same photon of light bounce back or is it absorbed then one with the same properties emitted? If the same one is bounced back does it's velocity ...
11
votes
2answers
6k views

How do mirrors work?

My physics professor explained to me that electromagnetic waves are consisted of two components - electric and magnetic - which cause each other. Which part of the mirror actually reflects the wave? ...
27
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1answer
6k views

How are photons “consumed”?

I have very little background in physics, so I apologize if this question is painfully naive. Consider the following thought experiment: an observer is in a closed room whose walls, floor, and ...
42
votes
7answers
35k views

What is the difference between a white object and a mirror?

I was taught that something which reflects all the colors of light is white. The function of a mirror is the same, it also reflects all light. What's the difference? Update: But what if the white ...
6
votes
1answer
6k views

How does a one-sided glass work?

How does a one-sided glass work? If seen from the outer side, we can see through thinking it is transparent, while if seen from the inside, the glass acts as a mirror. How?
22
votes
5answers
1k views

What longest time ever was achieved at holding light in a closed volume?

For what longest possible time it was possible to hold light in a closed volume with mirrored walls? I would be most interested for results with empty volume but results with solid-state volume may ...
9
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3answers
1k views

When light reflects off a mirror, does the wave function collapse?

This question is specific to the Copenhagen interpretation, which states that the wave function collapses on interaction. If we have a beam of light reflected off a mirror, whether you see this light ...
15
votes
2answers
8k views

How does reflection work?

In Newton's model of light as being composed of particles, it's easy to imagine reflection as being the rebounding of individual corpuscles off a surface. However, since light can also behave like a ...
24
votes
3answers
8k views

Does light reflect if incident at exactly the critical angle?

A lot of textbooks and exam boards claim that light incident at exactly the critical angle is transmitted along the media boundary (i.e. at right-angles to the normal), but this seems to violate the ...
3
votes
2answers
3k views

The Goos Hanchen shift mechanism

When the light is totally reflected in the interface between dense and less-dense medium, we know that the reflected beam will shift a little. Currently I have known the reflection coef r, will be a ...
21
votes
2answers
10k 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 ...
7
votes
5answers
14k 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 ...
316
votes
25answers
112k views

Why are mirror images flipped horizontally but not vertically?

Why is it that when you look in the mirror left and right directions appear flipped, but not the up and down?
69
votes
1answer
40k views

Why does a window become a mirror at night?

In day, when you look in the room through the window out, you can clearly see what happens outside. At night when it's dark outside but there's light inside you can look in the window but it becomes a ...
13
votes
1answer
3k views

Would the inside of a black hole be like a giant mirror?

As any light reflected or emitted from objects inside a black hole (if it is possible to be there) does not leave the event horizon and comes back inside, would it be like seeing yourself? What I ...
5
votes
1answer
2k 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 ...
1
vote
2answers
4k views

What temperature is achieved in focus point by 5000 flat 1x1cm mirrors onto a satellite dish?

There is this video ("R5800 Solar Death Ray") where teenager built a 5000 mirror device which concetrates the solar rays which is showing the potency of the mosaic method of concentrating sunlight ...
2
votes
4answers
11k views

Does light accelerate or slow down during reflection?

After all, it does change direction when reflection occurs. So shouldn't it also accelerate? And since the acceleration cannot increase the speed of light, mustn't it slow down?
12
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2answers
22k views

Two mirrors facing each other

What happens when you place two mirrors facing each other? Is it possible to have an infinite amount of reflections?
21
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5answers
16k views

Why is the surface of the Moon white?

Why is the surface of the Moon white? Rather, what makes the surface white?
16
votes
1answer
2k views

Why is not everything 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 ...
29
votes
3answers
7k views

Why is the light reflected at the same angle from mirror?

From the school physics I know that the material objects bounce from the plane surface at the same angle, losing some kinetic energy. In the same school I was taught that the light (and waves in ...
7
votes
2answers
6k views

What IS reflection?

How does quantum electrodynamics actually explain HOW reflection occurs on a microscopic scale? Note that Feynman's QED lecture series/book is not sufficient, as he only assumes that light DOES ...
140
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2answers
15k views

Why does a mirror split my laser beam?

Last night my daughter was asking why a mirror "always does that" (referring to reflecting a spot of light). To help her figure it out, I grabbed my green laser pointer so she could see the light ...
8
votes
4answers
131k views

Why do diamonds shine?

I have always wondered why diamonds shine. Can anyone tell me why?
16
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4answers
2k views

Is there a limit to the resolving power of a mirror telescope?

Like, if you grabbed the asteroid 16 Psyche and hammered it out into a disc of 1 mm thick iron foil and curved it into a telescope mirror with 2.4x the radius of the Sun, could you resolve details on ...
6
votes
1answer
342 views

Photons and perfect mirror

A perfect mirror means, that all the photons which collided with the mirror will be reflected in the same amount, with the same energy and with the same - except sign - angle. Will the mirror get an ...
2
votes
3answers
262 views

How does color (or reflection in general) work?

I'm confused, does the absorption and emission determine the color of something? Or does that only happen when something is emitting energy? When light hits an object, the photons get absorbed, then ...
5
votes
2answers
913 views

Principle of Reflection on atomic level

This well-observed phenomenon has, besides several others, always been a fascination to me. We are well aware of several theories, experiments, and practical applications of this well-known phenomenon,...
4
votes
2answers
940 views

Magnifying power of concave mirrors

Does anybody here know how magnifying power is defined for a concave mirror? I see these labels "5×" or "3×" on mirrors being sold as shaving mirrors or make-up mirrors. How is this defined? I know ...
17
votes
2answers
2k views

Why are so many different types of objects white, yet appear gray when they are wet?

There are many things with different textures that appear white – salt, beer foam, paper, shaving cream, snow, talcum powder, white paint, etc. The most common answer is all of the frequencies must be ...
16
votes
5answers
7k views

Are infinite reflections between two mirrors really infinite?

As written in the title it's a somewhat rhetoric question, so let me be more clear. Let's say I have two mirrors facing each other. They are perfectly aligned and perfectly reflective. I'm looking ...
14
votes
3answers
8k 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,...
9
votes
7answers
13k views

Why can we only “see” reflected light? [duplicate]

This is a question thats been bothering me a while. I don't even know if it makes sense or not (like if it is a physics question or becoming a philosophical one). But here it goes. The crux of my ...
6
votes
5answers
631 views

Trapping a lightray

Given a solid whose interior is a hollow sphere with perfectly reflecting mirrors. A small hole is drilled in the sphere and a photon is sent in at some angle. Will it always eventually exit through ...
3
votes
7answers
15k 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 ...
19
votes
3answers
5k views

Why is sound reflected and not transmitted through a wall?

We know that speed of sound is higher in a denser medium. So when a sound wave strikes a wall, why does it echo instead of passing through it with a speed faster than the speed of sound in air?
9
votes
3answers
12k views

Why there is a $180^{\circ}$ phase shift for a transverse wave and no phase shift for a longitudinal waves upon reflection from a rigid wall?

Why is it that when a transverse wave is reflected from a 'rigid' surface, it undergoes a phase change of $\pi$ radians, whereas when a longitudinal wave is reflected from a rigid surface, it does not ...
5
votes
3answers
4k views

Sign convention for mirror and lens formulas

I have just started learning optics at school and my teacher derived the lens and mirror formulas. While doing so, she applied the sign convention for $u$, $v$ and $f$ and arrived at the final ...
1
vote
2answers
791 views

Do photons bounce at mirrors? [duplicate]

I am referring to the simple mirror. How can a photon be reflected and what does that mean? Does it instantaneously reverse direction (in the case of 180 degree bounce), does it loose energy? What ...
7
votes
3answers
6k views

Does a reflection still transfer momentum to an mirror?

I have been recently wondering, if I take a powerful enough energy source (photon) and I have an perfect mirror exactly in front of it and assume an "emitter" shot the light towards the mirror. As ...
4
votes
2answers
811 views

Why is rainbow always circular?

From the article that I read on physics classroom website on rainbow, rainbow is formed with red on the top and violet on the bottom because violet refracts more, and has a smaller angle of deviation ...
3
votes
2answers
693 views

A mirror in the sky to look at past Earth

Earth reflects light from Sun into Space; are there any "mirror like" objects which reflect back to Earth this light? Has anyone been able to use this method to recover some information on how was the ...
2
votes
1answer
726 views

Diffraction by blazed grating via reflection: why is the reflection angle diffrent depending on $\lambda$?

Consider a blazed grating as the one in picture. It is possible to obtain a diffraction of a beam of light as in a trasmission grating (diffraction of reflection grating) and different wavelenghts ...
2
votes
3answers
957 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 ...
14
votes
4answers
9k 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 ...
50
votes
2answers
7k views

Why are gold mirrors yellow?

Why are golden mirrors yellow? Do they add a yellow component to the spectrum or absorb non-yellow components? If they absorb, then why are they used in telescopes being imperfect? If they add a ...