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Questions tagged [visible-light]

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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Looking for something to reflect ultraviolet light at extremely low wavelengths

I am looking for some sort of mirror that will reflect ultraviolet light at extremely small wavelengths (200-250 nm). The main purpose of it is to amplify the ultraviolet light and cause it to spread. ...
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2answers
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Why do thermal currents affect light but wind does not?

I notice if I put heat under a laser beam it will cause the beam to shimmer. The heated air is causing a disturbance in the air which affects the light. Yet, I can blast a stream of air from a ...
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1answer
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Curved Light stream?

I was wondering, a while ago, i asked if there is a way to bend light someway, which I got the answer is index of refraction. In this question I wish to know if this mention when applied with a dense ...
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0answers
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What is the difference between acoustic photon and acoustic phonon?

In the book Biomedical Photonics Handbook, 3 Volume Set edited by Tuan Vo-Dinh, it is written : Brillouin Scattering is caused by the interaction of the photon with the acoustic phonon. As the result ...
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1answer
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What is the colour of a yellow flower which is kept in sunlight watched through a red filter paper? [on hold]

Which will be the colour of the flower; can you see through it finally?
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6answers
85 views

Would A Perfectly White Room Always Be Lit Up?

I was thinking about this the other day, and I still can't find an answer. Theoretically, let's say there's a room and all the walls are painted perfectly white, meaning it will reflect 100% of all ...
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2answers
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Difference in spectrum of green laser and green LED

In an experiment I conducted I used a spectrometer to find the spectrum of green laser and green led. this is what I found: LED spectrum: Laser spectrum: why is the spectral width of the LED is ...
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0answers
40 views

Time and distance at the speed of light [on hold]

Considering a photon (or anything else moving at the speed of light) in it's own frame of reference. I'm having a discussion with someone and I'm trying to work out whether the time in that frame is ...
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3answers
101 views

What is the length of null geodesic?

There are many questions about this but none of them adresses my concrete question. If it is indeed true that for light we have $ds^2 = 0$ does that mean that in 4d spacetime total "distance" is zero ...
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Light Through Plastic Homework Help [on hold]

I am doing a piece of homework from Isaac Physics, and I have encountered this question: A beam of light travelling through air is incident upon a sheet of clear plastic of thickness 𝑑=2.80cm and ...
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2answers
56 views

Did diffraction bend this light more than 90 degrees?

Earlier I asked whether diffraction could bend light more than 90 degrees. earlier question Lambda gave me an answer. He stuck a razor blade into a piece of wood, and he shone a green laser at it, ...
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2answers
69 views

How does mirror reflect light (according to quantum mechanics)? [duplicate]

We all know that light is reflected from mirror but my question is that what happens at Quantum level when the process of reflection is happening? does the photon first get absorbed and then re-...
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1answer
106 views

What if a spaceship going half the speed of light turned on its headlights in both directions?

If the spaceship, travelling at c/2 were to turn on only its forward facing headlights, then after one second (relative to us, the stationary external observers) we would see that the ship has moved ...
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3answers
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Why does light go in the path where time is minimum and not maximum?

On deriving Snell's Law from Fermat's Principle there is a part where $\frac{ds}{dt}=0$ where $s$ is the distance gone by light. But the principle states that light takes the path where it takes ...
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2answers
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Are there any materials which are transparent only to some wavelengths of visible light? [closed]

So glass allows visible light through, but blocks UV light. Are there any materials which only allow certain wavelengths of visible light through? If so, what are the uses of this?
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2answers
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Do you feel the radiated heat of an explosion before you see it?

Do the infra-red rays reach us before the visible light does. I understand they have different wavelength but I don't know much else. Please answer the question if the explosion was in air and if it ...
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1answer
50 views

Is there an Heisenberg uncertainty relation for light polarisation?

While reading some questions about the polarisation of a photon, I was wondering about its quantum mechanical representation as a classical vector in the electromagnetic field operator : \begin{...
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1answer
52 views

Intensity of fringes in a Double Slit experiment

I have learnt that the intensity of fringes in a double slit experiment depends on the following formula: $$I = 4i\cos^2(\delta/2)$$ But it turn out that the intensity of th consecutive fringe ...
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2answers
37 views

Does the Sun cause star to appear in the sky on two different positions?

So, I was reading A brief history of time and it was talking about the sun bending the light of a star causing it to appear on a different place from where it actually was located. I was wondering if ...
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4answers
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What determines the color of the light emitted in a Tokamak?

We see images of Tokamak plasma with all sorts of colours from red to purple. Why do we see any light at all, since the plasma should be so hot to have dissociated all its electrons? It is all from ...
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2answers
81 views

Can diffraction bend light more than ninety degrees?

Is it possible for light to be diffracted more than ninety degrees? When light diffracts through a narrow slit or pinhole, it travels in all forward directions. The width of the slit determines how ...
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1answer
41 views

What causes these diamonds in water droplets on a screen?

It was raining yesterday and the screen of my iPad ended up covered in varying sized water droplets. As you can see, the smallest water droplets look transparent, and then as the size increases the ...
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2answers
29 views

Does diffraction happen from small slit width than its wavelength? [duplicate]

I always learnt in school that diffraction and interference happens if the slit width is of the order of wavelength. But what if the slit width is less than that of wavelength. Does diffraction ...
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2answers
31 views

Young Double Slit Experiment Formula - Nodal Lines

Some sources use the formula $\frac{X_n}{L}= (\frac{(n-\frac{1}{2})λ}{d})$, while other sources use $\frac{X_n}{L}= (\frac{(n+\frac{1}{2})λ}{d})$ when talking about destructive interference. Why is ...
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3answers
69 views

Does glass convert light wavelength?

I heard that when sunlight enters house through windows, it gets converted into longer wavelengths and gets trapped inside. So does the glass have anything to do with this or is this about heated ...
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2answers
48 views

Where does laser reflection (1) come from?

I have the above experiment setup where a triangulation-based laser scanner projects a laser (line) towards a transparent glass material. I then took a picture using my phone (indicated in the above ...
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1answer
43 views

Why is the thin prism always in the position of minimum deviation? [on hold]

Our textbook says that a thin prism (a prism of angle less than 10°) is always in the position of minimum deviation, but doesn't provide any explanation as to why that it is. What would happen if I ...
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2answers
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Why are green screens green? [closed]

How/why do green screens work? What's so special about the color green that lets us seamlessly replace the background with another image and keep the human intact? Are there other colors that work ...
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0answers
21 views

Dual nature of light [duplicate]

Light behaves as both particle as well as wave according to dual nature of matter. But if light behaves as wave then which type of wave - longitudinal waves or transverse waves?
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1answer
17 views

Why we see water like effects (reflection) at some distance from the driving seat on a motorway in sunny weather? [duplicate]

When we are driving on motorway in sunny afternoon we can observe a mirror like reflection on the road at some distance why is it so. !!?
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3answers
80 views

Why do we see virtually inverted image on concave side of spoon?

As we know that a virtual image is always erect then why do we see a virtual inverted image in the concave side of a spoon.
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1answer
66 views

Why don't we see inverted image while wearing spectacles? [closed]

We know that the lens in our eyes forms an inverted image on retina and brain reverses it to give the correct image. But when one wears specs the image would get reversed twice so we should see things ...
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2answers
2k views

Can light be compressed?

What if we take a cylindrical vessel with an inside surface completely reflecting and attach a piston such that it is also reflecting. What will happen to light if we compress it like this?
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5answers
7k views

Why can we distinguish different pitches in a chord but not different hues of light?

In music, when two or more pitches are played together at the same time, they form a chord. If each pitch has a corresponding wave frequency (a pure, or fundamental, tone), the pitches played together ...
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1answer
25 views

Blue LED light source

is it possible to change the color of a blue LED light source? Can the blue be filtered out to make white or some other color?
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2answers
57 views

Double slit experiment- light intensity

The standard explanation for the interference pattern is one of constructive and destructive interference between the light waves from the two slits. But, am I right in thinking that light intensity ...
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3answers
50 views

energy of a photon for a complex wave

If I use a plane wave of light given by $$E=E_o \sin(\omega t+\phi)$$ for photoelectric effect, then the energy of photon associated is given by $h\nu$ where $\nu=\frac{\omega}{2\pi}$ But suppose ...
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1answer
63 views

Are holograms in midair physically possible? [duplicate]

Is it possible for holograms, as in 3D projections of light in midair, to exist? Consider this image. If a projector, placed in the same position as the gray circle in the first image, were to ...
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1answer
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Influence of monochromator entrance slit width on spectral bandwidth

I am working with a Czerny–Turner monchromator (a Bentham TMc300, to be precise), with adjustable entrance and exit slits. I started by acquiring the signal with the slits completely opened, and I got ...
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1answer
60 views

Measuring speed of light [closed]

I have an interesting thought: could we use recursion between two mirrors to measure speed of light? It seems to be not really hard experiment. How could we do it? I'm not sure about how the picture ...
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1answer
57 views

Light reflection from a charged surface

Will we see differences (in intensity or spectrum) of visible light reflection from surface of positively versus negatively charged metal plate (or any non-conducting materials)? Are there data about ...
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0answers
32 views

YDSE - coherence of light from slits and width of slits

In Young's double slit experiment, 2 slits act as coherent sources. Why is coherence lost when the width of the slits is greater than half of the fringe width, i.e, if slit width is greater than the ...
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1answer
43 views

Can we see stars in day time by making use of a blue notch-filter?

Given on a clear sunny day, the only light that is blocking the star light is the scattered blue light of atmosphere. If we make use of a notch filter, which blocks only the blue light, can we get ...
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1answer
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Does a mirror reflecting a mirror's image go darker than the original mirror image or remain constant? Is there a constant ratio of decreasing light?

I noticed before that mirrors don't adequately reflect the light level of the room. My question was if there were two same caliber mirrors, one reflecting image of the first one, would it go darker ...
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1answer
32 views

Rayleigh Scattering and Red Giants

Rayleigh scattering is responsible for the color of the sky. Consider a planet with an atmospheric composition similar to Earth's but orbiting a red giant. Suppose further that the planet is in the ...
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1answer
34 views

How the intensity of light is related to the light wavelength?

Light can be seen as a wave or a particle. Light as a wave is well described by Maxwell's theory. Light energy relates to its wavelength and momentum too. However, if we treat light as a particle what ...
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How practical is a universal anti-fisheye lens (rectilinear)?

Is there a (practical) rectilinear lens that will "undo" a fisheye lens of webcam/phone size? To explain "practical", consider that there are clip-on lenses for phone cameras: wide angle, macro, and ...
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3answers
54 views

Circularly Polarized Light Through a Linear Polarizer

When a circularly polarized light is incident on a linear polarizer, shouldn't the transmission of said light be dependent on the momentary orientation of the polarization at the instance of incident? ...