Questions tagged [reflection]

This tag is for questions relating to reflection, the change in direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it originated. A familiar example of reflection comes from water waves; as the waves travel they reflect off objects that are floating in the water, and also reflect off the walls of the container holding the water.

When a wave reaches the interface between two different media, typically some of the wave will bounce back into the original medium. This process is known as reflection.
A familiar example of reflection is optical reflection in mirrors, where light waves reflect off a smooth surface.
The law of reflection says that for specular reflection the angle at which the wave is incident on the surface equals the angle at which it is reflected.
Light reflects from a smooth surface at the same angle as it hits the surface. For a smooth surface, reflected light rays travel in the same direction. This is called specular reflection. For a rough surface, reflected light rays scatter in all directions. This is called diffuse reflection.

1847 questions
375
votes
29 answers

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?
153
votes
2 answers

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 traveling from the source and reflecting off the…
Wayne Werner
  • 1,522
  • 2
  • 10
  • 13
94
votes
4 answers

Why does a yellow object turn white under a yellow light? Shouldn't it turn yellow instead?

Recently I was eating a yellow rice for lunch in a restaurant with only yellow lights. But the rice looked white! I was intrigued by this because I always thought it should look yellow since the yellow pigment reflects only yellow light, but the…
79
votes
1 answer

Why does soaking a fabric make it more transparent?

It's a well-known fact that when one soaks a thin piece of fabric, it will often become more transparent than it was before. What is the reason behind this? I can't put glass behind the fabric and increase its transparency. (Also, just in case this…
Isky Mathews
  • 1,965
79
votes
3 answers

Why does my beveled mirror make triplicate "ghosts"?

Here is a picture of my power adapter. You can see in has one green LED lit when charging. Now here is a picture of my mirror with beveled edges. When I view the power adapter in the mirror, I see three (3) projections of the LED: the original,…
istrasci
  • 1,033
77
votes
1 answer

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 mirror. Why?
Alon Gubkin
  • 873
  • 1
  • 6
  • 6
72
votes
9 answers

Why can't we see images reflected on a piece of paper?

Why can't you see a reflected image on a piece of paper? Say you put a pen in front of the paper, even when light rays are coming from other sources, hitting the pen, reflecting back, and hitting the paper, there is no reflection. What's wrong with…
katana_0
  • 1,195
61
votes
6 answers

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 it but everywhere the result is just used.The…
54
votes
4 answers

What wavelengths of light does a banana reflect?

I do know that there are at least two types of yellow light: a light of a single wavelength of ~580 nm and a combination of green light and red light. (Technically, there could be more yellow light.) And the following two figures are making me…
52
votes
2 answers

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 yellow component, then where do they take energy for…
Dims
  • 1,752
  • 14
  • 27
51
votes
3 answers

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's law, for example, in that case? Split by…
51
votes
7 answers

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 object is purely plain and does not scatter light?…
SMUsamaShah
  • 5,507
50
votes
4 answers

How can an object absorb so many wavelengths, if their energies must match an energy level transition of an electron?

I believe I have a misunderstanding of some principles, but I have not, even through quite a bit of research, been able to understand this problem. My current understanding of transmission, reflection and absorption is as follows: transmission…
48
votes
5 answers

What causes this pattern of sunlight reflected off a table leg?

My friend noticed an interference-like pattern around the table leg. However, we do know that interference patterns of sunlight produces rainbow colours. What seems to be happening here?
45
votes
12 answers

Why don't we hear sound reflecting from buildings, mirrors, etcetera?

We can see buildings, doors, cars etc. as light falls on it gets reflected to us. but why doesn't the same thing happen with sound? I mean why don't we hear sound reflecting that much?
Subhranil Sinha
  • 923
  • 1
  • 10
  • 20
1
2 3
99 100