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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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Trouble understanding difference Stokes and Anti-stokes

First, I have been trouble by so many Scattering and absorption event descriptions that stall my understanding of differentiating between each. I understand that Stokes is an absorption event. Two ...
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0answers
13 views

Radiation pressure on a reflecting cone

I know how to calculate radiation pressure for a reflecting and an absorbing sphere. But I am struggling to do the same for a reflecting cone. What is the radiation pressure experienced by a ...
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0answers
50 views

If time stops at the speed of light, how do photons vibrate in waves [duplicate]

I understand photons travel at light speed because they have no mass therefore they travel at the fastest possible speed, and at the speed of light time stops. If time is frozen at light speed how do ...
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2answers
53 views

How can Line of Sight work?

How can a mobile phone work inside a closed room with no openings if Line of Sight requires no obstacles between the receiver and transmitters? I know you may think it's not a Physics question but ...
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0answers
30 views

If a massless observer is going at the speed of light, what speed will it measure of a light beam going parallel to it in the same direction? [duplicate]

I got a different answer for this.Can someone please tell me if this is correct. https://www.quora.com/If-a-massless-observer-is-going-at-the-speed-of-light-what-speed-will-it-measure-of-a-light-beam-...
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1answer
44 views

Can a light source transpose another light source?

Scenario: Having very little physics background (high school), and having forgot most of it, sometimes I catch myself thinking about some weird stuff. Today's though was: given a stationary light ...
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1answer
39 views

Why doesn't shining light on a wire induce current in it?

If you accelerate magnet along a wire, an emf is induced in a wire because changing magnetic field induces changing electric field and thus electrons in wires are forced to form a current. So why ...
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2answers
43 views

Why does the intensity of light decrease as you move away from a particular point (described in question)?

I am trying to understand why the intensity of a light wave spreads out along a "back wall" which is near a light source (assume of a narrow bandwidth, ie. red LED). From our experience the answer is ...
2
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0answers
42 views

Could you actually see the event horizon of a Black Hole?

For years I thought to myself that surely you'd be able to see the event horizon of a Black Hole when looking at it against the surrounding light. I thought that it would be similar to this: Where ...
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0answers
14 views

Intensity of light entering a camera [on hold]

I read that the intensity of light entering a camera is proportional to the area of the aperture. But, the intensity of an electromagnetic wave like light is (1/2)e(E^2)c where e is the permittivity ...
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2answers
30 views

Why is the downward transition of electrons in a three level pumping scheme of laser non radiative?

Laser produces coherant monochromatic waves by stimulated emission of radiation. In the three level pumping scheme of laser the downward transition of electrons from E3 to E2 is spontaneous and from ...
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0answers
24 views

Difference in composition between solar energy and energy from a light bulb [on hold]

Can we use energy from a light bulb to power a solar cell? Why or why not?
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2answers
89 views

Does light have a non-zero mass? [duplicate]

I heard that the light has zero mass. But I searched in internet, some people say light has mass and some people said doesn't. I am not sure what is the right answer. And also I heard that the reason ...
2
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1answer
23 views

Is diffuse reflection same as Rayleigh scattering?

Is there a fundamental difference in their definitions?
2
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1answer
47 views

How does polaroid filter work at the atomic level? [duplicate]

I know it works by blocking electric or magnetic component of wave while allowing other but what happens at the atomic level , do the atoms absorb the electric component e.g by excitation of electrons ...
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0answers
30 views

Looking back in Time [duplicate]

Speed of light is a constant and every object reflects light to a certain extent. So the question goes - Theoretically, light reflected by Earth, say 200 years ago, would travel 100 light years and, ...
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4answers
89 views

Can Fourier transform be applied to light, as a way to find the individual elements of a color?

The Fourier transform can help one discern the individual frequencies of a sound. Every sound can be decomposed into sine waves. Knowing that light is a wave, that it "has" a frequency, is it ...
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2answers
30 views

Which field Passes Through the Polarization Film? Why Isn’t the Perpendicular Field Stopped?

When one EM field is aligned so that it can pass through a polarizing lens the other field (E or B) is 90 degrees out. Is only one of the EM fields affected by a polarizing lens or film? How is it ...
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2answers
66 views

If a massless observer is going at the speed of light, what speed will it measure of a light beam going parallel to it? [duplicate]

If a massless observer is going at the speed of light, what speed will it measure of a light beam going parallel to it?
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0answers
17 views

How does law of reflection work at the atomic level? [duplicate]

I read that when light strikes an object some of the frequencies of light are absorbed while others are reflected back this is explained in more detail by physics classroom: Visible Light ...
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2answers
62 views

what wavelength is white light made of?

Some sources say that white light = R+O+Y+G+B+I+V while others = R + B + G my question is do they divide the wavelength range (400-700nm) when they talk about RBG eg 400-500 = ...
31
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3answers
4k views

Why mixing of colors in paint is black, but mixing of light is white? [duplicate]

Mixing of different wavelengths of light results in white, but why is that when paint with different colors are mix results in black?
4
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3answers
170 views

Shouldn't “speed of light” really be “speed of electromagnetic waves”?

Since all electromagnetic waves travel at the speed of light ... shouldn't its name be Speed of Electromagnetic wave?
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2answers
15k views

In nuclear bomb explosions, witness describe their hands becoming transparent. How does that happen?

Witnesses of nuclear explosions have described their hands becoming transparent, and that they could see the bones. For example, see here. How does that happen?
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1answer
28 views

Principal focus question

On my notes İ have written that the definition of principle focus is : the point on the principal axes where rays appear to diverge or rays actually converge. However İ was looking at this diagram of ...
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3answers
642 views

Is the focal length of a mirror always shorter than the radius of curvature?

Is the focal length always shorter than the radius of curvature? If so, is there a reason for that? This is to help me when drawing ray diagrams. I am asking for spherical and plane mirrors. I ...
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2answers
39 views

Working principle of an optical stretcher

I understand that while using an optical stretcher experimental apparatus we attach a small dielectric ball to the specimen of study which can either be a DNA molecule, a Biological cell or any ...
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0answers
90 views

Are there proofs of the existence of photons that do not require light to be absorbed by atoms? [duplicate]

So far all the light quantum experiments I've read about, require light to be absorbed by atoms (detectors). Could it be argued that is that atom energy levels and frequency response are indeed ...
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1answer
30 views

Why does light bend towards the normal when passing through a denser medium?

When light passes from a medium with less refractive index to a medium with higher refractive index, it bends towards the normal. But why normal . Of course we can take an example of a car moving from ...
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2answers
59 views

Does anti-blue coating work less effective on high power lens?

I purchased a spectacle from an online website with anti-blue coating. The features of this product is mention here. Once I receive it, I started using the product without testing the anti-blue ...
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1answer
59 views

What type of mirage is this?

I am very new to the world of mirages and would like some information as to the type of mirage in this picture which I took this morning. It is the cargo ship African Kalmia which passed my location ...
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0answers
26 views

How bright is the area around a black hole over its lifetime?

I love Vsauce So naturally I began to think what anybody normal person (I have no friends) would think in this situation. Can light orbit a black hole. Apparently it can and its called a photon-...
5
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3answers
124 views

Are galaxies really structured the way they look in pictures?

Are real galaxies really structured the way they are in pictures online? I'm wondering this because if the speed limit of the universe is light speed, which means stuff we see on the sky or detected ...
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1answer
32 views

Question about Optical tweezers working principle

Why do particles on the periphery of the laser beam in optical tweezers apparatus drift to the center of the beam? What force pattern causes this pull to the center?
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3answers
582 views

If Maxwell's equations relate fields at the same point, how can waves propagate between different points?

There are lots of posts about EM wave model of photons, but I haven't read one that covers the more specific question I am focusing on here. Here How does energy transfer between B and E in an EM ...
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1answer
29 views

What is the mechanism by which light induce polarity in tiny particles?

I understand that the electric field in light induces polarity in tiny microparticles for example. Can someone explain the mechanism of how the vibrating electric field in light induces a dipole ...
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3answers
38 views

Rotor why not opaque?

Helicopter rotors spin at around 300RPM. Now for the naked eye they look like transparent, like if the rotors were not even there. https://www.quora.com/Why-do-we-see-individual-helicopter-rotor-...
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2answers
54 views

Momentum of a Quantum Wave

When single photons are repeatedly fired through a double slit apparatus, eventually an interference pattern emerges on the detector, suggesting that each individual photon actually propagates as a ...
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1answer
28 views

Polarization vision through a colour vision analogy

I'm writing to understand how polarization vision would work through the analogy of colour vision. I'm reading the research paper "Functional Similarities between Polarization Vision and Colour ...
12
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5answers
2k views

Applying the Heisenberg uncertainty principle to photons [duplicate]

The speed of light is a universal constant, so we definitely know the speed of the photons. If we know the speed, then we should not have any information about their location, because of Heisenberg's ...
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1answer
26 views

What's so interesting about the acceptance cone in fiber optics?

I'm reading about fiber optics and the concept of the acceptance cone. I understand the concept, if you shine light into the fiber in an angle higher than the acceptance angle, the light won't be ...
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4answers
117 views

Uncertainty Principle and the Momentum of Light

My admittedly limited understanding of the Schrodinger equation / uncertainty principle implies that as we narrow the range of possible values for the momentum of a photon, we necessarily increase the ...
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3answers
43 views

Reason for black and white colour

We always say that an object is black to a person's eyes if it absorbs all incident light or doesn't reflect anything, and white if it doesn't absorb and reflects all. My question is which specific ...
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1answer
40 views

When does the exchange of energy take place in the Quantum Eraser experiment?

I found this PBS video regarding the delayed choice / quantum eraser experiment, which, like all the others I've seen, states that the interference pattern generated by the photons that pass through a ...
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3answers
65 views

electron, photon and light [closed]

If electron and photon name theories, and not things directly visible, what exactly does light name in physics? What does a measuring apparatus measure in visible or everyday terms with respect to the ...
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2answers
76 views

Why is polarised light so bright? if polarizing lens are made to dim the light

I'm trying to learn about the physics of polarisation, which feels like an uphill battle. I've just read the notes from this page: https://www.microscopyu.com/techniques/polarized-light/introduction-...
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0answers
11 views

Laser light radiation interactions with biological tissues?

I was wondering what are the interaction between light generated by a laser source and biological tissues (e.g. human skin) in terms of geometric optics. I suppose from my studies that a part of the ...
55
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6answers
8k views

How does light combine to make new colours?

In computer science, we reference colours using the RGB system and TVs have pixels which consist of groups of red, green and blue lines which turn on and off to create colours. But how does this work?...
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3answers
56 views

Black Body radiation curve - Does it depend only on temperature.? [duplicate]

Couple of questions on Black body radiations 1. Blackbody emits a continuous spectrum. But blackbody is an idealized body. Do normal objects like a bulb or a table emit a continuous spectrum too.? 2. ...
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2answers
49 views

Black body radiation and spectra lines

My understanding was that all objects emit light of continuous spectrum when hot ( black body radiation) but then you see discreet wavelengths in spectra lines and I am confused. I know I am making a ...