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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1answer
238 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 ...
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2answers
74 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
46 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 ...
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1answer
101 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
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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
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2answers
306 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 ...
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1answer
38 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 ...
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2answers
89 views

Humans and color at night [closed]

Why we can't see colors at night?
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1answer
110 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 ...
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1answer
57 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 ...
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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 ...
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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 ...
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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
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1answer
75 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
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1answer
63 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
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1answer
20 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
89 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
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1answer
85 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
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2answers
292 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 ...
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2answers
299 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 ...
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0answers
42 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
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1answer
29 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 ...
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3answers
216 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
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0answers
53 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
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1answer
106 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
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2answers
127 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 ...
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0answers
15 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: $n(\lambda)=c_0+c_1/(\lambda-\lambda_0)+c_2/(...
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1answer
99 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
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1answer
32 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 ...
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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 ...
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votes
2answers
418 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
36 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 ...
-2
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1answer
87 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?
3
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1answer
80 views

Why can't we see better with an antenna?

Or alternatively: Why don't antennas look like telescopes? If visible light and radio transmissions are the same thing, why is there such a difference in the equipment we use for augmenting it?
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0answers
17 views

Can waves change their roll axis?

If I roll a laser emitter 90 degrees on its roll axis, will the "up" and "down" motion of the laser-light wave also roll with orientation to the emitter so that to me it is now osculating "side" to "...
0
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1answer
194 views

Angle of minimum deviation

A prism of angle $60^\circ$ deviates a ray of light through $40^\circ$ for two angles of incidence which differ by $11^\circ$. What is the refractive index of the glass of the prism? If we are given ...
0
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1answer
103 views

burning candle flame disturbed by unseen force .What could this force be?

If a burning candle were placed in a enclosed glass box with a sufficient amount of oxygen to stay ignited, What outside source could interact with the flame causing a disturbance?
0
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1answer
28 views

Is there a limited light waves emission rate?

Is there? I mean, say, the sun emits light waves towards us and those waves travel through vacuum at the speed of light, or c. But does the sun emit those waves in ...
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2answers
69 views

Will light continue traveling after the source has stopped producing light? [closed]

Will light continue traveling after the source has stopped producing light?
0
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1answer
43 views

How did Cavendish measure the deviation of light from the Sun?

On today's date in 1731 was born Henry Cavendish. He is mainly know for his Chemistry research, however, while I was reading his biography I've noticed that he also calculated the bending of light due ...
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2answers
89 views

Is it possible for two strong lenses to cancel each other effects?

Is it possible for a lens system for 2 strong lenses to cancel each other, so it looks almost the same as a common glass, while at the same time making an object in between them appear big and distant?...
0
votes
1answer
103 views

How can travelling at light speed affect light itself? [duplicate]

~Hypothetical Scenario: Your driving in a car (with the headlights on high beam) and you gradually get faster until you reach the speed of light. Raised Assumptions: You can see in and out of the ...
0
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0answers
34 views

Why can we treat (most) metals classically at room temperature?

When we consider how light and metals interact with each other at room temperature, the Drude model, which is a classical theory, is usually and successfully used. My lecturer explained something ...
0
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2answers
102 views

How does thin film interference work?

So thin film interference is when light is half-reflected half-refracted then the reflected and refracted wave interfere with each other to produce another color. What I don't understand is that the ...
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3answers
79 views

How does color (or reflection in general) work?

I'm confused, does the absorption and emission determine the color of something? Or does that only happen when something is emitting energy? When light hits an object, the photons get absorbed, then ...
0
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2answers
48 views

Diffraction of light

If $l_1$ and $l_2$ are parallel how can they both can hit same spot? Why their difference in path length is $l_2 - l_1 = d \sin \theta$ instead of 0?
1
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1answer
52 views

clouds reflective property

I am a private pilot and see some beautiful clouds in all forms and patterns up in the sky. I wonder what causes some of the clouds to be so shiny, reflecting such an intense light that it's hard to ...
0
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1answer
46 views

Interactions of light with the air

This is an interesting thought which I had when driving home today looking in my wing mirrors. If you are driving a car and looking in your, say, right wing mirror, you see an image of the car ...
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3answers
2k views

Why does water reflect light?

Why does water reflect light? What is actually happening when light is reflected by water? We know why metals reflect light; water, however, is not metal, but it still reflects light and we can see ...