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167
votes
17answers
53k 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?
42
votes
1answer
5k 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 ...
24
votes
7answers
4k 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 ...
16
votes
4answers
2k views

Why can't my eye see itself in the mirror through polarizing 3D-glasses?

I found a pair of polarizing "3D glasses" lying around, and tried to look at myself in the mirror while wearing them. To my utter confusion, when closing the left eye and only looking through the ...
16
votes
2answers
3k 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 ...
14
votes
2answers
499 views

Would you see a rainbow from refraction when the sun is in front of you?

I know how rainbows are formed, and why. Usually it is said that the Sun must be behind the observer, in order for its light to be totally reflected inside the droplet and then reach the observer. ...
14
votes
1answer
448 views

Why does the spotlight reflected off of a rectangular mirror tend to become circular?

Background and setup When I was 12 I used to like a girl, we were almost neighbors and it was essential that our parents don't find out. So whenever one of us wanted to call the other they'd signal ...
14
votes
1answer
1k views

Why does my watch act like a mirror under water?

I have a digital watch, rated to go underwater to $100 \rm m$. When it is underwater it can be read normally, up until you reach a certain angle, then suddenly, it becomes almost like a mirror, ...
14
votes
4answers
659 views

Thought experiment regarding an object approaching a mirror

Here's a thought experiment I came up with in class today when my mind drifted (I however highly doubt I'm the first to think about this since it is pretty rudimentary) : Let's say superman ...
13
votes
4answers
8k 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 ...
12
votes
5answers
531 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 ...
12
votes
3answers
538 views

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

Like, if you flattened out Ceres to a 1 mm iron foil telescope mirror with 20x the surface area of the Sun, could you resolve details on the surface of an exoplanet? Could you make it arbitrarily ...
11
votes
2answers
410 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 ...
9
votes
6answers
2k views

How come an anti-reflective coating makes glass *more* transparent?

The book I'm reading about optics says that an anti-reflective film applied on glass* makes the glass more transparent, because the air→film and film→glass reflected waves (originated from a paraxial ...
8
votes
1answer
779 views

Glass that only allows light of specific amplitude to pass through it

Is there a type of glass, mirror or lens that allows only lights of amplitude equal to or greater than a fixed value to pass/reflect through them?
8
votes
3answers
2k views

Why does your reflection stay the same size when you move further away from the mirror?

This was an experiment I saw in my son's workbook. It said to mark out the top of your forehead and the bottom of your chin on a mirror using a whiteboard marker. Then slowly move backwards, and ...
8
votes
1answer
2k 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?
8
votes
4answers
2k 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 ...
8
votes
2answers
276 views

Do mirrors have a “resolution” quality to them?

I would like to know if mirrors have a quality of "resolution" to them like a regular photograph might, or like a JPEG does. For example, if you looked to closely, or magnified a photograph, you ...
7
votes
2answers
3k 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 ...
6
votes
5answers
364 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 ...
6
votes
1answer
734 views

Polarization and mirrors

When a light beam reaches a dielectric surface, the incident and reflected beams have different intensities depending on polarization. For the so-called Brewster's angle, the reflected light is ...
6
votes
1answer
354 views

Wavefront RMS errors, mirror surface roughness and Gaussian beam scattering

What I'm interested is in the scattered power of Gaussian beams reflected from mirrors with a given surface RMS. Usually the surface RMS $\sigma_{s}$ of a mirror translates in an error for the ...
5
votes
3answers
6k views

What is the color of a mirror?

A mirror couldn't be white, as then you wouldn't be able to see your reflection so clearly. It wouldn't be transparent, as that then won't reflect. So what color is it?
5
votes
3answers
2k views

How can I determine transmission/reflection coefficients for light?

When light rays reflect off a boundary between two materials with different indices of refraction, a lot of the sources I've seen (recently) don't discuss the relation between the amplitude (or ...
5
votes
2answers
217 views

About photons and mirrors

If a photon hits a 'perfect' mirror (with no environment interference) would the mirror move a bit?
5
votes
5answers
377 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 ...
5
votes
2answers
666 views

Distance of objects in car mirrors

We've all seen that label on our passenger side mirrors that says, "Objects in mirror are closer than they appear." Why is this? Further, why does it only apply to the passenger side mirror, and not ...
5
votes
5answers
886 views

Why does light reflect more intensely when it hits a surface at a large angle?

I mean, what is happening at a microscopic level to cause this behavior? Here's what I got from Wikipedia: On Reflection (physics)#Reflection of light it says that "solving Maxwell's equations for a ...
5
votes
2answers
3k views

Reflection of transverse and longitudinal waves

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
1k 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 ...
5
votes
1answer
51 views

Capture reflecting image

Suppose you have following installation: ...
5
votes
2answers
445 views

Why does a glass window reflect white objects white from an atomic scatterers’ viewpoint?

Related: Is a white object always white? If you are standing in front of a glass window during the day, you can see your dim white t-shirt’s reflection in the window. The reflection is dim because ...
5
votes
1answer
172 views

How is it possible for an Ultrasound device to correctly interpret a negative density change in tissue?

I understand the principles of Ultrasound Imaging, and the mathematics behind sonar velocity, impedance, and reflection. I also understand that an Ultrasound device recieves an echo produced by ...
5
votes
1answer
954 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 ...
5
votes
1answer
270 views

Special Relativity & Mirror Reflection

If you move at $5$ $ms^-$$^1$ towards a plane mirror, your reflection moves $10$ $ms^-$$^1$ towards you. But what happens if you're moving much faster, say $0.8c$? Would your reflection move at ...
5
votes
1answer
1k views

How does the aluminium foil do the thermal and WiFi isolation?

Aluminium foil is widely used for thermal isolation. As far as I know it reflects the thermal infrared radiation. Also I've seen a lot of guides about strengthening WiFi signal by putting the ...
5
votes
1answer
134 views

Reflectivity of a glowing-hot metal surface

When a polished piece of metal (or steel in particular) is heated to incandescence, how do its reflective properties change? Given a mirror-like surface, would the object temporarily cease to act ...
4
votes
5answers
1k views

Focusing Light with Flat Mirrors

What is the best way to focus (sun)light using flat mirrors? My goal is to start a fire. Cutting the mirrors is easy.
4
votes
2answers
1k views

How do mirrors work?

Apparently, light is just a certain wavelength, or "the visible spectrum" of electromagnetic waves. If I recall correctly, my physics teacher explained to me that electromagnetic waves are basically ...
4
votes
1answer
444 views

Why can't I see far when I look in a mirror?

I'm myopic. It's a fact. I understand exactly how it works because Internet told me light rays encounter themeselves too soon in my eyes... that is why I can't see far objects even if I see near ...
4
votes
1answer
168 views

Why does the light at the bottom of the pool form this awesome pattern?

Take a look at the following picture: Why does the light at the bottom of the water form this pattern? I have also seen the same phenomenon in all the swimming pools I've ever visited, of whatever ...
4
votes
1answer
132 views

Light entering in a 0° angle, is there any reflection?

Is there any reflection of light that enters a new medium at a 0° angle, if the electric field is such, that it is completely in the plane of the double layer?
4
votes
2answers
349 views

How long do reflections take?

How long does it take for a photon to be reflected? Starting with the photon being absorbed by some atom to the point it's reemitted? And what's the same point with pressure waves, like sound?
4
votes
1answer
490 views

The Interactions of Light and Matter

So basically, I was trying to find a good answer to the question of how light interacts matter. Namely on the quantum level what causes matter to appear transparent, reflective, opaque, etc I came ...
4
votes
3answers
531 views

Virtual images in (plane) mirrors?

The following image is taken from teaching physics lecture Was man aus virtuellen Bildern lernen kann (in German): Now the cited paper claims that the left hand side is the correct picture to ...
4
votes
1answer
126 views

How does light pass through rough glass?

Light incident on a rough surface will be diffuse after passing it. Angular intensity depends on the grinding of the glass surface. I'm trying to find information about the scattering indicatrix of ...
4
votes
1answer
84 views

Why does static electricity not make a charged body reflective?

If mirrors work by deflecting photons by free electrons in surface layer of mirror, so it could be possible to take a glass pane and provide it with extra free electrons by giving it massive static ...
4
votes
1answer
882 views

Why do some materials reflect (metals) and other materials reflect and refract (glass) from the quantum perspective?

Recently I was asked to explain the difference between reflection and total internal reflection from a purely conceptual standpoint (no math). Let me explain what I already know. Reflection and ...