Questions tagged [optical-materials]
282 questions
118
votes
6 answers
Why is glass transparent?
Once I asked this question from my teacher and he replied "Because it passes light.". "And why does it pass light?" I asked and he said, "Because it is transparent.".
The same question again, Why glass is transparent? Why does light pass through it,…
SMUsamaShah
- 5,507
37
votes
4 answers
Why are the edges of a broken glass almost opaque?
Unfortunately I broke my specs today which I used in this question.
But I observed that the edges are completely different then the entire part of the lens. The middle portion of the lens was completely transparent but the edges appeared opaque (and…
Ankit
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32
votes
3 answers
If we repeatedly divide a colorful solid in half, at what point will the color disappear?
Suppose I have some colorful solid, which I cut into two halves (both are identical). Take the first and cut it into two parts, and then repeat this again and again. I know that a single atom doesn't have a color. So there will be a point at which…
Himanshu
- 12,211
29
votes
7 answers
Why don't opaque objects reflect light?
My sister was doing a quiz and I tried to point her in the right direction by giving her scenarios to imagine. One of the questions in the quiz was:
Which of the following objects do not reflect light:
Polished metal
Mirror
Undisturbed…
Glowingbluejuicebox
- 1,309
21
votes
4 answers
Why are no metals green or blue?
Copper is orange; gold is yellow; silver, platinum and lead are white (chromatically speaking).
Why are there no metals that are blue or green?
Why do the colours of cold metals follow, more or less, the same red-orange-yellow-white sequence that…
Sod Almighty
- 327
20
votes
2 answers
Why is diamond transparent while graphite is not?
Diamond and graphite are both made of the same atom, carbon. Diamond has a tetrahedron structure while graphite has a flat hexagonal structure. Why is diamond transparent while graphite is not (at least not with more than a couple of layers)?
Marijn
- 3,408
19
votes
1 answer
How can the refractive index be below 1 in a dielectric?
Upon checking the optical properties of different dielectrics, I found the interesting case of $Al_2O_3$. It seems to be reported with a refractive index below 1 in the infrared range of $10 - 12~\mu m$, for example by Kischkat, Boidin and Querry.…
DK2AX
- 4,860
11
votes
2 answers
What percentage of light gets scattered by a mirror?
Sunlight strikes a mirror at a 45 degree angle. The vast majority of light will be reflected about the normal. Some light will be absorbed by the mirror. Some light will be transmitted through the mirror. And some light will be scattered in all…
causative
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11
votes
1 answer
How do non-mechanical solid-state optical switches work?
I am currently looking for a fiber-optical switch (FOS) in order to be able to change the light source of a spectrometer. As this will be used in harsh conditions, I was hoping to find a FOS with no moving parts.
Today I came across this, which…
huhnmonster
- 213
9
votes
2 answers
Is the visible light spectrum from "red-hot glass" at least close to Blackbody Radiation?
Briefly, for visibly transparent materials like glass, you can see through then even while they are glowing red hot. Most glasses have plenty of absorption in the IR, so there is plenty of absorption and re-emission going on. But once a visible…
uhoh
- 6,089
8
votes
2 answers
What are the current experimental limits on the polarizability of the vacuum?
Many (all?) materials are polarizable at some level; meaning that when we apply an electric field across the material, there is an induced dipole moment
$$
\vec{p}=\alpha(\omega)\vec{E},
$$
where $\alpha(\omega)$ is the polarizability of the…
Chris Mueller
- 7,233
7
votes
2 answers
Slowing down light in an opaque crystal for a whole minute
I just read about a team of physicists at the University of Darmstadt, Germany, that managed to completely slow down a beam of light that traveled through an opaque crystal (article here).
How is it possible for a beam of light come to a complete…
Reds
- 758
7
votes
1 answer
What is the energy loss in total internal reflection?
In total internal reflection light inside a dense medium reflects from the boundary to a less dense medium. Since by Snell's law there is no allowed refracted ray, all energy continues along the reflected ray. In the wave picture there is an…
Anders Sandberg
- 34,657
6
votes
2 answers
Could a transparent frequency-altering material be possible?
I would imagine a material that is transparent but a electromagnetic wave going out will have a lower frequency than when going in (and maintaining it's direction). You could build glasses to see UV-light with that.
Has an effect like that been…
Walter
- 63
6
votes
2 answers
Why can't ultraviolet light pass through glass?
What factor determine whether a body behaves like a transparent object for EM waves of a particular frequency?
user621951
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