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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2answers
27 views

How do you convert RGB lux into a singular value?

I'm trying to understand the output from an RGBW optical sensor. According to the specification for the sensor this outputs lux. I was hoping someone could explain how the 3 RGB lux values relate to ...
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1answer
30 views

What would the rainbow look like if we could see the full EM spectrum? [duplicate]

Would the rainbow look different if we could see the full EM spectrum (or at least a lot more of it)? Would the width of a rainbow be bigger and would all wave lengths of light be in a rainbow?
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1answer
24 views

Light / TEM wave in a hollow waveguide

I'm cramming for my EMF exam, and a question came up: Light in free space is an example for a TEM wave, isn't it? (Maybe thats already my mistake) And we learned that in a hollow waveguide only TE ...
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2answers
79 views

“X-rays”, “gamma rays”, “sun rays”… But electromagnetic waves are NOT rays and DO NOT consist of rays?

In a separate question I'm struggling to figure out the nature of EM waves. But it's a vast topic and I'm trying to narrow it down to small specific questions. It turns out that all electromagnetic ...
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0answers
31 views

Point View and the relativity of everything, also regarding seemingly neutral pen and paper formulas - also, the nonexistence of black holes [on hold]

I am just a programmer with a love for math/physics and ... science fiction, haha! Anyway, to state it right in the beginning: This question is related to the following postulation (of mine, but ...
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1answer
39 views

Why do night sky appear red when it is cloudy?

Since childhood, I have seen that whenever at night, the sky is cloudy, the sky becomes red. But, clouds are grayish, so it is expected that the sky becomes more darker. But no, it is not! Why does ...
2
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1answer
30 views

Determining path of light through a nanolens

In the case of light passing through stacked liquids, we can use a ray approximation of the path of light to determine the path taken through each layer of liquid using Snell's law. From all the ...
2
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1answer
74 views

How can radiation be a transverse wave? Does light really resemble a rope? How can a 3D field be a medium for non-spatial 1D waves? Need mental model

I understand longitudinal waves. For example, I've got a clear mental modal of air waves: a slice of air becomes overcompressed, then the slice next to it becomes overcompressed and the first slice ...
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3answers
65 views

Path of light as it travels between two black holes

What would happen to light passing through a narrow space between the event horizons of two equal-mass black holes? Would it deviate or follow a straight path?
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3answers
35 views

Diffuse laser light in a surface

Im building a laser target. It consists of a box, with a black plexiglass circle in the center of one of its sides, and a larger white circle around it. The black for the inside shots, and the white ...
3
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1answer
95 views

Why do we use the index of refraction for yellow light?

When we do problems with optics and refraction, we’re usually given a set of indices of refraction to work with; for example, the index of refraction in air is about 1.00, the index of refraction in ...
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1answer
50 views

Do parallel rays reflecting at a mirror not intersect at one point? [closed]

Let's take a concave mirror with $CP$ as its principal axis. Let's assume that a parallel ray $p$ to $CP$ reflects at $A$ to pass through the focal point $F$. Then, $\angle CAF=\angle ACF$, which ...
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1answer
38 views

Brightness of light sources

I would like to know what determines the brightness of light.I'm confused,After hours of reading i got these definitions mixed up i need to link them together : Light intensity Brightness of light ...
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0answers
27 views

How to actually determine the Index of Refraction of an object in different colors of light?

I would like some guidance as to how the IOR of an object is determined in different colored lights. Taking for example diamond, I know that the base IOR is 2.417, and the respective wavelengths of ...
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0answers
21 views

Variations in electric field of a light speed charged particle

From the question " Is there a travelling speed of for electric field? If yes, what is it?" I get to know electric field propagates at speed of light. What if a charged particle which creates this ...
1
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1answer
36 views

Is crystal diffraction actually diffraction?

It seems like a very common model that is taught in schools for crystal diffraction is that there is an incident plane wave of light on a crystal lattice, and each atom in the lattice scatters the ...
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0answers
18 views

Propagation of force thought experiment [duplicate]

Imagine you have a million rigid spheres lined up edge to edge in a way that they can only move in one direction. now imagine that there is a wall at one end of this alignment. If you were to push at ...
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1answer
34 views

Is there a formula to calculate the deviated angle of a ray passing through a prism?

I'm assuming the angle of incidence to be the number of degrees from a perpendicular line on the side of a prism the ray starts passing through... I'm trying to figure out the angle the ray would be ...
2
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0answers
49 views

Spectroscopy from a classical light wave or photon only?

In chemistry we mostly regard light/electromagnetic radiation as a beam of particles or photons. This is a very useful model to explain molecular excitations and ionisations from quantum interactions. ...
1
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1answer
36 views

Can you use infra-red goggles (or similar principle) to see through mist and fog?

As per title really... fog is obviously quite opaque to visible light yet transparent to radio waves. What is the range of frequencies at which fog is opaque, and is either end of this range at a ...
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0answers
22 views

Does light follow magnetic flux lines? [duplicate]

Will light naturally tend to align itself to magnetic flux lines?
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2answers
80 views

Why do sea waves seem to be standing still when you look from the window of an airplane?

Looking from the window of a passenger plane even at moderate altitude such that one can still recognize individual waves and even something like white foam, and small boats close to the cost line, it ...
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1answer
67 views

Can electrons reflect light?

Lately, I have been watching sparks while connecting my electronic devices and I can notice that electricity is kind of blue, and theoretically it's blue because it reflects blue wavelengths?? And ...
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2answers
80 views

How can light enter a black hole if it cannot get out?

I have known for a very long time that light cannot exit a black hole. I can even understand some of the simpler reasonning about it, such as escape velocity, or space geometry inside the black hole. ...
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0answers
12 views

Electrons in a gas discharge tube

I'm having some difficulty understanding regarding electrons in gas discharge tubes. My understanding is the following: In a gas discharge tube the gas must be at low pressure in order to be ...
2
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1answer
37 views

White light to blue light

When white light falls on a blue colored translucent material and passes through it the light changes its color into blue.Similar phenomenon is observed when yellow light passes through red glass in a ...
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0answers
16 views

How does a hologram record the incident laser?

How does the hologram (the photographic plate) record the incident laser beams when they hit onto it, what happens inside the hologram so that it records these laser beams?
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3answers
58 views

Is sunlight truly white?

I recently purchased a book on nuclear astrophysics, with no goal of mastering the topic but merely to read in between exams and hopefully learn something, it is revealed that the sun is composed ...
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2answers
61 views

is there a way to capture scenes from past? [closed]

Is there a way to capture scenes from past for ex/ capturing someones sound which lived before long time ago.. if yes, how? and if no, why? Regards
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1answer
22 views

Reflection of light at a microscopic level [duplicate]

I always read that light is reflected by a mirror! My question is how does reflection takes place at microscopic level? Mirror is just atoms and electrons are revolving around the nucleus ! So where ...
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0answers
14 views

Single slit diffraction and fringe width

I know that intensity of the bright fringes will decrease on moving away from centre and width of the central fringe is 2 times that of the second fringe. Does the width of other bright fringes ...
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6answers
4k views

Can UV light make us invisible?

For an object to create different EM waves, it needs to increase the temperature, so what if we or some material could be so hot, that it would emit ultraviolet light, and thanks to that be invisible ...
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1answer
32 views

Circularly polarized light and polarizing filter

Does circularly polarized light pass through a linear polarizing filter, regardless of the orientation of such filter?
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1answer
37 views

Can infrared lasers still do damage to things if they are powerful enough?

So I get that infrared light is not visible to the human eye without some sort of device to assist in helping you see it, but I was just wondering how that plays into things like lasers. I know you ...
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0answers
23 views

YDSE and diffraction

In a single slit diffraction experiment we know that light bends around the edges. So can we treat Young's double slit experiment (YDSE) as a two slit diffraction since we're using two slits in that ...
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1answer
25 views

What wavelength of light is the term 'focal length' defined against? [closed]

Because different wavelengths of light are bent differently in a medium, the focal length ought to be different for each of them (which is why white light splits up into a rainbow). If I have a "25 mm ...
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2answers
56 views
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0answers
23 views

Does tracing paper over a solar panel count as hard shade or soft shade?

For my Physics IA I conducted an experiment to see how shade on solar panels affects the output power. I applied and secured one layer of tracing paper over the solar panels of my solar charger at a ...
2
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1answer
24 views

How does light filtration work?

How exactly do certain types of glass filter out light within specific frequencies/wavelengths? I'm wondering because I read somewhere that certain types of windows filter out certain parts of the ...
4
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1answer
51 views

What, if anything, makes primary colours distinct?

I've recently become interested in the primary colours; red, green and blue. In my capacity as a computer programmer I'm well aware of how these colours are used practically, and of how varying ...
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0answers
36 views

Can we control lightning?

Lightning has great energy that can even make some damages, so I was wondering if we could control it, and is it even possible to predict which thunder clouds will form lightning?
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1answer
57 views

Why mirrors form image and others don't?

In the case of mirror, I understand how a image is formed, If I replace plane mirror by wood or some other opaque material in the above image and position of object(bottle) and eye remain the same , ...
1
vote
1answer
37 views

Textbooks or papers that clearly explain second harmonic generation?

I'm having trouble learning about Second Harmonic Generation. I've found a bunch of sources, but they all seem to expect a fairly advanced level of knowledge about it. For example, in the wiki section ...
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2answers
59 views

reflection of light and the uncertainty principle

I've heard that light reflects the same angle that it falls and so if we know the position of photon (the spot where it hits the surface) and the direction of where it shall go - that's violation of ...
4
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2answers
308 views

Computations using light

I recently found out about analog computers. They really intrigue me. I've seen a few videos on how mechanical computers work. I also know that there are electric analog computers too (I have no clue ...
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2answers
63 views

Why lasers and not light? [closed]

Some laser applications consist simply concentrating light into a small spot (e.g., image projection, welding, cutting, etc.). Why are lasers used instead of a simpler light source?
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1answer
56 views

Why we don't observe spherical rainbow?

We have seen or heard of rainBOW and circular rainbow but not any other shape probably due to the shape of water droplets. My question is why can't we see a spherical rainbow?
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2answers
59 views

Photoelectric effect and light coming in chunks

I was watching a lecture on introduction to quantum mechanics.While explaining the photoelectric effect,the lecturer mentioned that we must think of light as coming in chunks with each chunk having ...
4
votes
5answers
204 views

What about a surface determines its color?

Light falls on a surface. Some wavelengths get absorbed. The other are reflected. The reflected ones are the colors that we perceive to be of the surface. What is the property that determines, what ...
3
votes
1answer
37 views

Why do we use Mie scattering to describe light scattering off large objects?

I'm an undergraduate sutudent who has recently come across Rayleigh and Mie scattering and I'm trying to understand them a little better. As I understand it Rayligh scattering is used only when the ...