Questions related to the perception and measurement of light (primarily in the visible range), its mathematical description, the reproduction of colors by different means, color combinations, etc. Please use the tag [electromagnetic-radiation] if you want to refer to the general form of light.

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2
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2answers
42 views

Space station illuminated by the Earth

Let's say that we have a space station orbiting the Earth around the equator at a speed of 360 degrees per 24 hours, always being roughly on the line between the centers of the Earth and the sun. From ...
1
vote
0answers
40 views

Will the flash light accelerate in space? [duplicate]

As we know from school physics course light has pressure. So my question is will flash light accelerate in space in the direction opposite to light emission? If not, then will flash light with ...
0
votes
2answers
92 views

At which times does light act as a wave and at which times does it act as a particle? [duplicate]

Is light a "particle", that exists as a photon or as a "wave", the usual electromagnetic wave. If it's both when does it exist as a "particle" or a "wave"????
15
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4answers
3k views

Why can't I see the blue color scattered by the lower atmosphere of the earth?

I understand that the blue colour of the sky is because of the scattering of blue light by molecules in earth's atmosphere. The scattering appears to be happening from molecules that are far above in ...
2
votes
0answers
43 views

How does refraction work? [closed]

https://www.youtube.com/watch?v=YW8KuMtVpug&feature=iv&src_vid=CiHN0ZWE5bk&annotation_id=annotation_187211 Start the above video at 8:15. How does the phase velocity affect the apparent ...
28
votes
3answers
4k views

Why aren't all objects transparent?

I know that for an object to be transparent, visible light must go through it undisturbed. In other words, if the light energy is sufficiently high to excite one of the electrons in the material, ...
0
votes
0answers
45 views

What is the formula for light emission from a point source in scattering media?

I'm trying to model the light output emitting from a point source somewhere in R3, and impinging on a fiber optic at distance r, that may be angled relative to the point source at some angle $\theta$. ...
0
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0answers
28 views

Modeling total absorption using absorbance of multiple visual layers

I have a question involving light absorbance versus absorption. It applies to a stack of different photoreceptor types. I understand the difference between absorbance, which is basically equal to ...
0
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0answers
30 views

If we had a radio antenna produce visible light? [duplicate]

If we had a radio antenna produce visible light would it degrade the quality of the antenna due to the light production. How fast would be the degradation?
0
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0answers
35 views

What is the exact meaning (distribution) of unpolarized light?

Are there statistical properties to unpolarized light? For example, is the polarization of individual particles in an unpolarized beam has a normal distribution or a uniform distribution etc. of ...
2
votes
1answer
52 views

Veterans Day Memorial in the U.S

For the ones who know about it: How many more times will the Veterans Day Memorial stones' holes "align" perfectly? Some info from this site: At precisely 11:11 a.m. each Veterans Day (Nov. ...
-1
votes
2answers
42 views

Would it be possible to have light that is a cross between a laser and a none laser light? [closed]

Normally light moves through all three dimensions which is why it's intensity at any particular point depends on the inverse of the distance squared. For practical purposes we can say that laser ...
0
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2answers
76 views

Light wave particle duality

I have studied about the dual nature of light and all the experiments that proved light was a wave and sometimes a particle, and I am comfortable with the concept that it can be both. However, I have ...
0
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0answers
34 views

Does nature of light depends on its Time of Interaction?

I was trying to understand how to "feel" about light. I have formed a notion which I couldn't find anywhere. So please tell if I am correct. Also please give theoretical explanations if possible (and ...
1
vote
1answer
103 views

Calculating the color temperature and intensity of skylight with an algorithm

I think it will be possible to calculate the natural sky light intensity and color balance (CCT) based on time of day/year, GPS location. Has anyone seen a formula/algorithm for this? I would like to ...
0
votes
0answers
54 views

Index of refraction for travelling EM wave problem

Let $n_1$ be the index of refraction of the first medium and $n_2$ be the index of the second medium. When $n_2>n_1$, then for an incident angle of $90^{\circ}$ we get a refracted light at a ...
3
votes
1answer
207 views

Refraction: Energy flow, tunneling and Evanescent EM waves

In the full internal reflection case where we have a refracted evanescent wave, If another object is nearby, then we could have wave tunneling phenomenon(frustrated total internal reflection). I am ...
0
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2answers
70 views

Confusion in difraction experiments

I had a confusion in the diffraction experiment about which I was taught in school. According to the formula we Derived The width of the central maxima decreases on decreasing width of slit and vice ...
0
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2answers
43 views

Photons reflecting off matter

When photons reflect off matter, do they always lose momentum to the object? If they lose momentum to the object, that means they lose energy, and so their frequency should decrease. However, when we ...
0
votes
1answer
84 views

light effects of electric current

In german high school textbooks and curriculua, the distinction of following main sorts of effects of electric current is usual: magnetic, heat, light and chemical. My question is, whether the glow ...
7
votes
2answers
1k views

How can a slowed light ray bend?

If light is traveling through air, it slows down and ends up bending. But how? If I'm running straight, and I get slowed down, shouldn't I still be running straight?
6
votes
2answers
231 views

Why can we see the earth from outer space if the sky is blue?

As far as I know, the sky is blue because as light from the sun enters the atmosphere composed primarily of wavelengths of visible light. However, as the light happens across molecules of oxygen and ...
0
votes
1answer
34 views

Is an iPad screen an Optical Prism?

One day, I noticed that sometimes, when there is an iPad right below a light, such as a chandelier, when viewed from an angle, one can see what looks like a spectra of colors. Is the iPad screen ...
0
votes
2answers
84 views

Humans and color at night [closed]

Why we can't see colors at night?
1
vote
1answer
93 views

Why do 3d movies have a red and blue “double image”? [closed]

My question is why do 3d movies have a red and blue"double image" that is basically just a few inches to the right and left of the real image. And how does this help us see the image as "3d". Does it ...
0
votes
1answer
54 views

How can a material be conductive and transparent at the same time?

Transparent conducting films for example. On one hand, the band structure of transparent materials must have a large enough HOMO-LUMO separation. On the other hand, conducting (metallic) materials ...
0
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0answers
15 views

Can measuring the refraction index in an object measure the strength of the quantum gravity between atoms of the object? [duplicate]

Is measuring the refraction index of an object a way of measuring the strength of the gravitational force between the atoms of the object (measuring quantum gravity)? From reading Snell's law of ...
0
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0answers
30 views

What is the pure form of energy? [duplicate]

What is the pure form of energy? Einstein in his energy mass equation derivation said that electromagnetic radiation is pure form of energy.
0
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1answer
38 views

How long will the light exist inside the sphere?

Ok, so let's say we have a very thick, but hollow, metal sphere. The inside of the sphere has a radius of 100 meters. The sphere also has a door that can be opened and closed and when closed makes an ...
0
votes
2answers
84 views

Photoelectric effect and energy of light

I have a doubt about photoelectric effect and the nature of light in general. From what I understood, in order to ionize a piece of some material, I need an electromagnetic wave with a frequence ...
0
votes
1answer
74 views

Can more than one photon be in the same space as another photon?

I have heard light described as a particle that travels in a wave. I have heard that waves are unique in that two waves can take up the same space as they are travelling, either through constructive ...
1
vote
1answer
54 views

Why is blue darker than yellow in an analog black and white photograph?

Blue is perceived darker than yellow by the human eye, because of biological principles within the eye. I can understand that therefore, when making a picture black&white in software like Adobe ...
0
votes
1answer
19 views

Which coefficients are needed to numerically obtain transmission spectrum?

I'm using Omnisim program. I would like to obtain transmission spectrum of certain material so I have created two polynomials: one representing real refraction coefficient and one representing ...
2
votes
2answers
87 views

Why can I always see a star? [duplicate]

Light moves along straight lines... Got it. So if the light from that faraway star is traveling in a straight line, and that beam is, considering the distaces involved, at best one or two photons ...
0
votes
1answer
64 views

Ultraviolet light in dark environments

I was looking into night vision equipment recently and found that some work with ultraviolet light. How much ultraviolet light is around at night? Is there enough ultraviolet light to see in the dark, ...
3
votes
2answers
284 views

Will high amplitude, low frequency light be capable of wrapping around a macroscopic object? [duplicate]

To me, as a macroscopic observer of light, it appears that light moves in straight lines. If I shine a light at object A and object B moves between me and object A, the light hits, i.e. gets blocked ...
1
vote
2answers
248 views

Can matter have 100% reflection?

Is it possible to have matter that reflects all the light and does not absorb light at all? If thats possible then we can store light inside it right? I think we can trap light inside that matter in ...
0
votes
0answers
41 views

Speed of Light with trains [duplicate]

Suppose that there is a train (train1) going at 100 km/h. The train is infinitely long. Suppose that there is an other train inside train1 (train2), which has a speed of 100 km/h also. So for a ...
0
votes
1answer
28 views

Finding the distance from the center of airy disc to first airy minimum?

This image is taken from the manual of photography, by Elizabeth Allen: How do I find it? The formula is supposed to tell me how to find this distance, but the formula requires R which depends on ...
1
vote
3answers
209 views

Can two 2500 K light bulbs replace one 5000 K bulb for growing plants indoors?

In an effort to assist an old Greek woman I find myself in need of greater minds. A 5000 Kelvin light bulb is required for her indoor fig plant. Can I get away with substituting two bulbs each in ...
2
votes
0answers
50 views

The properties of light photons [duplicate]

Please consider a closed room with light reflecting walls and in the centre of the room there is a Lighting Bulb. Now if I switch on the bulb, the room is obviously illuminated with light. When I ...
0
votes
1answer
80 views

What exactly is light? [duplicate]

What is light in terms of physics? Whenever looking for definition on the internet getting explanation or translation of my language, a common definition/explanation for light was Light is light. ...
2
votes
2answers
106 views

Why doesn't dielectric materials have coloured reflections like conductors?

I'm a 3D artist trying to learn the basic (or perhaps even intermediate) level of physics of photorealistic rendering. But most artist and tutorials on the internet have little to no clue of the ...
0
votes
0answers
14 views

What is A2L refractive index polynomial?

I'm working with a photonic modelling software and in the manual I saw that I can specify refractive index of modelled material with following polynomial: ...
0
votes
1answer
94 views

Would a camera that only takes light at 90 degrees work?

From what I understand cameras and biological eyes work in a similar fashion, they all take light in a cone and distances are perceived as the angle which the object takes up rather than it's physical ...
0
votes
1answer
30 views

When light is reflected, if some of the light is absorbed in the particle, does it change the particle?

Which color/frequency of the light is absorbed and which part is reflected? How is it determined which part will be absorbed? Does that depend on the particle? N.B: When I say particle, please keep ...
-1
votes
1answer
38 views

What are diferent reflection percentages of different colors?

I don't need any accurate answer. Suppose reflection percentage for white is 100% (which is not even true for mirrors) then what will it be like for different colours like violet, green and red etc of ...
-2
votes
2answers
323 views

Light and vision (why we can't see without light) [closed]

I have heard that light comes from object and we are able to see the image of that object. But I can't understand why we can't see without light and how we are able to see object but not in dark. MY ...
1
vote
1answer
35 views

What are some of the empirical proofs of electromagnetic polarization? [closed]

I am aware of how polarization follows from Maxwell's equations, and how it is possible in transverse waves in general. I also know that Huygens, in his great Treatise on Light, first discovered and ...
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votes
1answer
84 views

If photons do not have mass, why does light get attracted such that it cannot escape a black hole? [duplicate]

Does gravitational force of black hole attract the light? Or is it something else?