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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What is the definition of a Projection? [on hold]

This may be a stupid question. But here it is... Can the scenarios below be reffered to as projections? 1) A projector projects an image onto a white screen. 2) A LCD display forms an image on a ...
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11 views

Is there a noun for a material that absorbs, scatters and luminesces?

I know Luminophore is used for molecules or nanocrystals which absorbs and emit light, and Scatterer is used for materials which scatter light (elastically or inelastically). I suppose it would be ...
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47 views

Why violet light bends the most? [duplicate]

I have read about refraction through a triangular prism,rainbow formation and other natural phenomena.They all told about the strong bending of violet light . I know that it has a shorter wavelength ...
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Affect of walking upto and beyond lightspeed [closed]

Setup: a giant planet rotating at the speed of light(L) + 1m/s at its equator (E) Assume at E ± 1m the speed of rotation is L Also, at both the South and North Pole the rotation is 0m/s such that ...
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39 views

Classical (non-quantum) explanation for the transparency of glass?

Is there a classical explanation for the transparency of glass? How did physicists explain the transparency of glass before quantum mechanics?
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The effect of velocity on dispersion of light

It is stated that red light bends less than blue light as white light is dispersed through a glass prism. I understand that red light travels faster within the glass because of its higher wavelength, ...
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1answer
54 views

Why does the soap bubble shine with the colours of the rainbow?

Is it because of refraction of light in water? a mixture of UV rays in sunlight? polarization of reflected light? interference of light reflected from external and internal film surface? or maybe ...
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1answer
11 views

What effect will moving one light source closer to the screen have on the diffraction pattern of two coherent light sources?

Say that you have two coherent light sources to begin with, each the same distance away from a screen, but then, you move one of the light sources closer to the screen by a fraction of the wavelength ...
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Very Basic Diffraction Question [closed]

"A white light shines vertically down on a horizontal CD ROM disc. The disc is viewed by a teacher whose eye is a horizontal distance 0.50 m from the disc and 0.35 m vertically above its ...
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1answer
34 views

On seeing and especially in the dark

Our retina detects the change in the electromagnetic field due to the jiggling of the atoms surrounding us as I understand the seeing process. In the total absence of a light "source", however, why ...
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2answers
28 views

Light Polarizer for Photons

This is maybe a noob question. I read that if unpolarized light is passed through a polarizer that only allows vertical polarization, then if this light is passed through a diagonal polarizer, only ...
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What is the average energy of visible light photons, of what we perceive to be white light? (i.e. visible spectrum of 5500K radiation)

Visible light is anything between 1.65eV and 3.10eV, so the answer is somewhere between these values. Naively we could average this to 2.375 eV, but that would not be actual average of full spectrum ...
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Why is the road hard to see when it’s wet?

Ok, pretend it’s night time and I’m driving down the road with my headlights on. If the road is wet, it’s harder to see; that’s a given. But why? I’d assume it’s because less of the light from my ...
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Why do objects reflect laser light?

Why do non-red objects reflect red laser light? The color of things explained as "Objects reflect in the color that we see them, and absorb other colors." But if to illuminate, say, a yellow thing ...
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2answers
36 views

Is their a way to protect screens from being recorded? [closed]

This idea might sound stupid but... Is there a way a screen would be impossible to record using a prism? I’m not talking recorded by a software but recorded from a camera… If you put a prism layer in ...
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1answer
33 views

Vision bluriness

I don’t know much about vision so I hope one of you guys could clarify me… When people who have vision problems look at an object without their glasses, they’ll see this object with a certain level ...
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Reverse engineering visible color spectrum with night vision glasses

Here's the context from a discussion I was having with a friend. Let's say I have a picture on my phone. Would it be possible to watch this picture on my phone with night vision glasses who usually ...
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Self-illumination vs lumimance

I'm using a graphics format reading library. There are three luminance modes for materials available, which I'm trying to wrap my head around: Self-illumination, which I interpret to mean "glow", as ...
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2answers
67 views

Spectral colours

If we shine a prism with white light we get the light spectrum.I am interested what will happen if we block all the formed spectral components but the yellow light and let the yellow pass through ...
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1answer
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Why is the sky near the Earth limb warm-colored, even far from the sun?

I've seen many sunset pictures with explanations. The sun is red, the areas adjacent to it is orange, then yellow... because redder lights bend less, and the air is thick at that angle. Far enough ...
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1answer
25 views

Why does a photomultiplier tube (PMT) traditionally present better signal-to-noise ratio (SNR) than an avalanche photodiode (APD)?

Empirically, a photomultiplier tube (PMT) is said to present better signal-to-noise ratio (SNR) than an avalanche photodiode (APD). Some materials say that it is attributed to the higher gain and ...
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4answers
89 views

Do photons emitted by grow lights really lose energy over the distance of a few feet?

I have watched videos where they test grow lights PAR(Photosynthetically active radiation) values at different distances. It seems to me that at the speed light is moving, a foot or two should not ...
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1answer
38 views

How does the eye see a real image?

If we look at a convex mirror diagram, it produces a real inverted image at the bottom. Let's say a person's eye is above the object. How do the reflected rays reach the eye? since it's a concave ...
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Newton's explanation for interference [duplicate]

If Isaac Newton believed that light is a particle, then how did he explain the interference phenomena?
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1answer
45 views

In femtosecond Raskar photography of a light pulse, why is the light pulse not length contracted?

If length contraction is a physical phenomenon, as many (not including myself) believe, then at a trillion frames per second, Raskar photography should be able to pick up the length contraction of an ...
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Is every kind of energy quantised?

I know this is been asked on this site before but I felt unsatisfied by its one answer. I’m familiar with the concept of quantisation, I keep reading that “energy is quantised” but what do they mean ...
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1answer
128 views

In quantum mechanics, which concept caters for light rays?

If photon wavefunctions are omnidirectional and don't have a definite size, how comes those from the Sun don't all collapse on Mercury and some do actually reach Earth ? I understand that ...
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4answers
119 views

How exactly is white light a combination of several wavelengths? [duplicate]

I have read that light is an electromagnetic wave. Every ray of light has a specific wavelength. The colour perceived by any observer is dependent upon the wavelength of the incident light. What I ...
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1answer
24 views

Refracting an image through 2 prisms

my question might be quite simple for some of you but I don't have any idea what the result of such an experiment would be... If you would take an image emitting light such as a video from a screen ...
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2answers
115 views

Why does gradually increasing refractive index coating reduce reflection?

Why does gradually increasing refractive index coating reduce reflection? EDIT: As @Michael Seifert nicely describes in his answer, reflection only occurs if there is an abrupt change in refractive ...
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1answer
39 views

Does the curvature of light around a “centre star” in gravitational lensing affect the age at which we view the object being “lensed”

It occurred to me that during gravitational lensing, the light curves around a given object, creating a curved path. Because the path of light is curved, and thus, longer than a straight path, would ...
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1answer
47 views

Can someone explain why optical rotation occurs?

Optical rotation occurs when carbon atom is surrounded by different groups. But how does that affect the direction of light? And why does it happen only for plane polarised light? My thought - if ...
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1answer
81 views

Understanding radiation of objects

I am trying to understand Greenhouse effect. I have heard that during the day the earth absorbs heat from the sun and during the night it looses heat in the form of infrared radiation. Does earth ...
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1answer
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Focal plane of ideal thin lenses and spherical mirrors

Recently I was studying about optical instruments and in my book I came across a point which stated that When non axial parallel rays are incident on an ideal spherical mirror at a small angle or a ...
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55 views

Calculating Laser Beam Intensity Absorbtion

This question pertains to the ability to calculate the laser beam intensity , at a particular point in time when using lasers for the purposes of Cutting and Engraving Materials. The parameters at ...
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2answers
60 views

Does light have mass? Why? [duplicate]

I've been wondering whether light has mass. Yet given the wave-particle duality of light, the statement seems to be affirmative. With that, how to calculate it?
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90 views

Effect of metal disks on diffraction of light [closed]

Recently, I started to go deeper into physics. I don't speak English well, so I'm sorry. This experiment was carried out in Hungary 25 years ago. The measurement results were not accepted by the ...
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2answers
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How are radio waves different from the rest of the EMR spectrum?

Radio waves are generated by connecting high frequency AC electricity to an antenna (e.g. a dipole antenna), and we can control the frequency by the frequency of the AC. The frequency of other EMR (e....
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3answers
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Is this test question/answer about light absorption accurate? [closed]

A blue object appears black when illuminated with which color of light? A. Green B. Yellow C. Cyan D. Blue E. None of the above Answer: B. Yellow Justification: A blue object ...
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How to shift light to a longer wavelength / lower frequency energy level so that it becomes a different “color”?

I need to shift light from a certain wavelength/frequency to another, lower, level. For example, green light down to yellow or orange. I want to reduce the energy level of the transmitted light, for ...
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2answers
103 views

Question about zooming out with optical lens

I need some help. I am working on a project and I am wondering if it is possible to make an object to look 100 times far away than it is actually using lens (or more than one lens). The lens (or ...
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How does reflection work at a quantum level? [duplicate]

Thinking of light in corpuscular form, how does the bouncing of a photon off a reflective surface work? Is it the same photon bouncing off, or is it absorbed and re-emitted? If it's bouncing, does it ...
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2answers
101 views

Can light travel through a maze? [closed]

I want to manufacture a light proof enclosure. I need to understand: if I design a cap with a "U" section profile edge and the body with "T" or "U" section profile edge, will light be able to get ...
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Creating some sort of optical transistor

Is there a way to create an optical transistor that runs using a cheap laser and made using mirrors and lenses? My point of using that is to make an optical logic gates, but there is another problem ...
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6answers
240 views

How many quantum mechanisms are there to create Light?

I know light is created when an electron moves to a lower energy orbital in an atom. Is this original source of all light we see (sun / light bulbs / fire) or is there another way to produce light ...
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Estimating focal length using light

I am considering how to estimate the focal length of a dynamic lens (such as biological lenses) non-invasionally, i.e., without harming the animal. The mammal lens changes its shape depending on ...
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0answers
22 views

How does light pass through any glass? [duplicate]

This might be a very stupid question for Science students, but I had this doubt always, since childhood. I still don't understand even when I'm adult because I didn't read science in detail. When I ...
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1answer
37 views

Double slit diffraction and interference patterns

i'm a highschool physics student trying to understand diffraction and interference etc. I'm confused about this (in the context of the double slit experiment): if an underlying interference pattern ...
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1answer
39 views

Path difference that is between 0 and 0.5 or similar [closed]

A question in a new physics textbook we are using in school tasks readers with determining the path difference and them commenting on whether it would result in constructive or destructive ...
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4answers
132 views

At the Fundamental Level, are Radio Waves and Visible Light Produced in the Same Way?

I'm currently writing an essay, that aims to investigate claims that the radiation produced by radio towers (i.e. radio waves) is harmful to human health, using physics Ideas To approach this I've ...