Tag Info

121

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 ...

44

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 ...

33

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 ...

22

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 ...

14

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 ...

13

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.

12

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 ...

11

See http://en.wikipedia.org/wiki/Polarized_3D_glasses. Most likely you have a pair of circularly polarized glasses. The mirror reverses the circular polarization. EDIT: http://en.wikipedia.org/wiki/Circular_polarization does it better than I would be likely to achieve in less than an hour or two. Or Hyperphysics, ...

11

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 ...

11

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 ...

10

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 ...

10

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

10

Other answers are correct except that they forget to mention why white objects behave differently than mirrors. Well, generic white objects have very rough bumpy surfaces. This causes scattering. On the other hand, mirror has a very even and polished surface so that the simple law for specular reflection of incoming rays holds. Of course, you can also ...

10

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 ...

10

The question is not just about the question whether Superman's image represents a "real piece of information". It's clearly not actual matter located at the appropriate point in space. Instead, the image is a virtual place defined by certain criteria. But the fact that the image isn't quite material doesn't mean that you should switch back to Newtonian ...

10

I think the answer to this mostly has to do with psychology and not physics. When we estimate the size of something we use surrounding objects as a reference. Here is a photo of me in a non-magnifying mirror: After that I turned the mirror around to the magnifying side and tried to take an identical photo at an identical distance: Notice my hand over ...

9

The set-up you are describing is essentially an optical cavity, and you are asking what is the longest lifetime which has been achieved in such a cavity. In this paper (also described here), S. Kuhr et. al. describe a supraconducting cavity with a 130 ms lifetime. It is essentially 2 curved mirrors face to face. It works in microwaves (51 GHz), which has a ...

9

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 ...

8

First, I just want to remind readers that it is NOT true that "more glancing angle always means more reflection". For p-polarized light, as the angle goes away from the normal, it gets less and less reflective, then at the Brewster angle it's not reflective at all, and then beyond the Brewster angle it becomes more reflective again: Nevertheless, it's ...

8

This question cannot really be answered because you cannot travel at the speed of light. See Accelerating particles to the speed of light If you were massless, you would always travel at the speed of light. However, in that case you would not perceive the passing of time. In relativity, the time that passes for an observer depends on the proper time. The ...

7

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 ...

7

In addition to Fresnel equations, and in response to your question regarding the "... relation between the amplitude of the transmitted/reflected rays and the original ray": $$T_{\parallel}=\frac{2n_{1}\cos\theta_{i}}{n_{2}\cos\theta_{i}+n_{1}\cos\theta_{t}}A_{\parallel}$$ ...

7

Sticking to 2D for simplicity, the transformation matrices for reflections in the x = 0 and y = 0 lines are: $$R_x = \left( \begin{matrix} -1 & 0 \\ 0 & 1 \end{matrix} \right)$$ $$R_y = \left( \begin{matrix} 1 & 0 \\ 0 & -1 \end{matrix} \right)$$ Any combination of these transformations can be given by $R_x^m R_y^n$ where $m$ and $n$ ...

6

This was intended as a comment, but for the sake of clarity, I'd better use an answer. Regarding to the case $\mu \neq 1$, we can start using the following set of equations, which are derived from the Maxwell equations and after applying boundary conditions that demand that across the boundary the tangential components of $E$ and $H$ should be continuous. ...

6

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 ...

6

Think about where a point above, below, left, and right of your point of view are in the reflection. Your head is still on top, your feet still on the bottom in the mirror. Likewise, your left hand is still to the left and your right hand to the right. It seems flipped because, to look behind you, you are used to turning around (which swaps left/right), ...

6

Dear Rootosaurus, when you're looking at an image of a chair behind you in a flat mirror, then you're observing the so-called virtual image of the chair. If the mirror's surface is located in the $x=0$ plane and the coordinate of the real chair is at $(x,y,z)$, then the virtual image of the chair is at $(-x,y,z)$. However, the light rays coming from the ...

6

When mirrors give distorted images like that, it's usually because they're slightly curved. A "fun house mirror" is a typical (though extreme) example of this effect. So to get a realistic image, all you need to do is find a mirror that is as flat as possible. The placement of the mirror doesn't have any effect on whether the image is distorted, although it ...

6

Some theoretical answers were provided, but here's a practical answer from an astronomer's point of view. (First off, the resolving power is given by diameter, not surface area. So we will talk about diameter here.) For visible light, the practical resolving power of a 100mm diameter mirror is 1 arcsec. A 200mm mirror: 0.5 arcsec. And so on. This is the ...

6

The phenomenon you're looking for is called total internal reflection. You could also have a look at this link for more information. To draw a comparison with glass : In glass (for the most part) when you incident light onto it, it gets refracted on one surface, and gets refracted again at the other surface and leaves the material. This doesn't always ...

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