# Tag Info

173

Here's a video of physicist Richard Feynman discussing this question. Imagine a blue dot and a red dot. They are in front of you, and the blue dot is on the right. Behind them is a mirror, and you can see their image in the mirror. The image of the blue dot is still on the right in the mirror. What's different is that in the mirror, there's also a ...

52

Any translucent surface both reflects and refracts light. By refraction, I mean that it bends the light a bit, but lets it through to the other side. Now, reflection for such surfaces is much less than refraction (unless there's total internal reflection, but thats irrelevant for glass+air). Edit: According to @JohnRennie (see comments), only 5% of the light ...

48

Because they don't flip left with right (or up with down), they flip the 3D space you're standing in "inside out", so far from the mirror becomes far away inside the mirror and vice versa. A hand 1 meter from the mirror seems like it's 1 meter on the other side of the mirror but in the same spot with regards to left/right so nothing is flipped. Wiggle your ...

32

This common confusion stems from our familiarity with photographs. We forget that we rotate them to face ourselves. Take a picture of yourself and hold it up in front of you. Probably you are holding it so that you can see your image. If so, you "flipped" the image of yourself when you rotated it 180 degrees around the vertical axis. When you look to the ...

30

The difference is the direction the light is emitted in. Mirrors 'bounce' light in a predictable direction, white objects scatter light.

29

The highest resolution 3d printers I know of are around 1600dpi, which is a resolution of about 15$\mu m$. Telescope mirrors have to be smooth to fractions of a wavelength of light, so the resolution of current printers is nowhere near good enough. Whether 3D printers could one day be good enough is a different question, but given that the improvement in ...

26

Telescope mirrors and other mirrors used by scientists telescopes regularly do use a silver coating. See for instance here. However, aluminum coating are the norm (certainly for the large primary mirrors deployed in telescopes) because of durability reasons. I quote from the text linked to above: The challenge with using silver as a coating material is ...

22

You are right. Rainbows can occur all over the sky. However the traditional one and two internal reflections of the primary and secondary bows send light back towards the sun and hence their bows appear opposite the sun and centered on the antisolar point. The reflection of the main light makes these bows stand out. And only the light that enters a droplet ...

19

The simple answer is that the two devices work in completely different ways. Solar cookers, as well as so called solar thermal collector focus the light of the sun and heat somethings (a pot in a cooker, some oil or ceramics) and the heat is then transferred somewhere, where it generates electricity, usually by some steam engine. So, the more heat, the ...

19

It's easier with images... The mirror doesn't flip left and right as you can see in the upper image. The so-called flip occurs when somebody in the real world rotates 180 degrees about the vertical axis to see you face to face, as can be seen in the lower image. Regards Hans

19

See the Wiki article on Polarized 3D glasses. Most likely, you have a pair of circularly polarized glasses. The mirror reverses the circular polarization. The article on Circular polarization does it better than I would be likely to achieve in less than an hour or two. Or Hyperphysics, or Google.

18

Take a picture and look at it. Now turn the picture to face the mirror. Question one: who flipped the picture? Answer: you did. Now, face the picture back to you, and walk to the nearest refrigerator. Turn the picture to face the refrigerator. Wow! Refrigerators flip images too! Don't believe me? Take your flipped page and hold it up to a bright light. The ...

18

A white object reflects the light in all the directions, independently of the original direction. It is called a diffuse reflection. If you shine a beam of light onto a white surface, it is scattered in all the directions. On the other hand, a mirror reflect the light symmetrically to the input direction, with no scattering. This is what allows us to see ...

17

Light cannot move outwards inside the event horizon. I would guess you're thinking that an outgoing light ray might leave you in the outgoing direction, then slow to a halt and return - hence you would see yourself. However this doesn't happen. The light leaving you moves inwards not outwards, but since you fall inwards faster than the light does, the light ...

16

Johannes makes a good point about durability. As a footnote, I'll add that aluminum has another nice property over silver, at least as far as your plot shows: constant reflectance over the visible spectrum. Look at the slopes of the lines from $400\ \mathrm{nm}$ to $700\ \mathrm{nm}$ - silver varies from $80\%$ to $95\%$ reflectance, while aluminum stays ...

16

First, lets separate the concepts; there is nothing that is "flipped" in the mirror image regarding one orientation more than others. the full group of transformations $O(3)$ includes transformations where $det(R) = -1$. You can consider the following transformations examples of this: 1) they have one random direction flipped in sign, or 2) for the special ...

16

In similar situations, one could observe the wave properties of light except that this is not the case here. The mirror could be imperfect except that it's usually very close to flat so this is not the reason, either. Your observation has another simple reason: the Sun isn't a point. It's round. That's why the light rays coming from the Sun are not exactly ...

15

A mirror, or a perfect mirror at least, is the same colour as a perfectly white sheet of paper. Both a perfect mirror and a perfectly white sheet of paper reflect all the light that hits them. The difference is that the paper scatters the light so what reaches your eye is a mixture of all the light hitting the paper, while the mirror reflects the light ...

15

Although the other answers are correct, I think they are missing the main point. Ordinarily, solar panels work regardless of their orientation. Their performance may be optimal when oriented directly toward the Sun, but if the Sun shines at 45°, 90°, or when it's cloudy, they still receive photons and still generate electricity. Focussing mirrors, ...

15

Yes, there are. Such materials are called "saturable absorbers," and are (or at least, have been) used as switches in some laser designs. The one I recall is a nickel acetate dye, although there are others. Basically, the molecules absorb single photons at the laser wavelength, but when the intensity is great enough that two photons are absorbed ...

14

The mirror gets proportionally smaller. The explanation is the similarity of triangles. The eye and the marks on the mirror form a triangle, while the eye and the two points on the image form another triangle. The two triangles are similar, with ratio 1/2, no matter the distance.

14

Here's how I explain it (this is pretty similar to most of the other answers). Assume the mirror is hanging vertically on a wall, and you're standing upright and facing it, looking at your own reflection. (Just to make the assumptions explicit.) And let's assume that you're facing north, and wearing a watch on your left wrist. The mirror doesn't flip ...

14

This is a general property of waves. If you have waves reflecting off a clamped point (like waves running on a string that you pinch hard at one point), the waves get phase inverted. The reason is the principle of superposition and the condition that the amplitude at the clamped point is zero. The sum of the reflected and transmitted wave must be the ...

13

What you are observing is total internal reflection. Snell's law tells you that, for a ray transmitting through a surface $n_{1}\sin\theta_{1} = n_{2}\sin\theta_{2}$, where $\theta$ represents the angle of reflection from the surface, $n$ represents the index of refraction of the substance in question, and the labels 1 and 2 represent the source medium and ...

13

It is overdefined geometry. By most optics ray tracing simulation software it will be treated as absorption. The intersection point belongs to two interfaces at once. Praxis differs Two separate mirrors are likely to produce scattered light, as mentioned by @Carl Witthoft E.g. Glas substrate, which is cemented at the interface to a second mirror. A light ...

12

The problem with most of the earth-moon pictures is that they show the Earth and moon very close together - which suggests that the moon is in the earth's shadow for almost half of the time. So in the picture linked to above - it looks like a full moon should be dark. The real picture is more like this

12

Cinema 3D glasses (at least those made by Read-D) are circular polarized. This has the advantage that the polarized light reflected from the screen doesn't depend on the angle between your eye and the screen and so you can move your head around while watching. But when you look in a mirror the rotation direction is reversed on reflection. The shutter ...

12

This question has a great pedigree! Supposedly it's what Einstein asked himself when he was first thinking about relativity. The answer is that you can't "ride on top of a light stream" -- that is, you can't go as fast as the speed of light. The speed of light is invariant -- same for all observers. So at any sub-light speed you can see yourself in a ...

12

This question reminds me of Zeno's paradoxes. It is assumed that the two mirror surfaces are absolutely parallel. In classical physics the electromagnetic waves that create the reflections are uniform and the energy loss due to the reflection ( depending on the material of the glass) will be what will make the reflections fainter and fainter , but the ...

11

Imagine a mirror placed on the floor. Your face, looking at it, will be pointed downwards; but the face "in the mirror" is "looking" up. The other answers here are great — I just wanted to make sure we discard the assumption that the mirror is placed on a wall!

Only top voted, non community-wiki answers of a minimum length are eligible