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
114 views

Is it possible to apply force to a light particle?

I know, the universal speed limit is the speed of light $c$. So, is it possible to apply more force to a light particle? What would happen to it if we could?
2
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1answer
102 views

If the effects of gravity cannot travel faster than the “c”, does this mean we are only gravitationally bound by masses in our observable universe?

I'm 17 and fascinated by the differences and omissions Newton made in his equations of motion. However it makes sense that gravity can't travel faster than light because of the force-carrying ...
0
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1answer
34 views

What is the fraction of the incident intensity passing through polarized sheets?

Unpolarized light is incident on a set of three polarizing sheets as shown in the figure at right. The polarizing directions of the sheets make angles 10°, 55° and 85° to the vertical. What fraction ...
5
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1answer
925 views

Why is the shadow of a wind turbine a bit slow at first then very quickly, etc. and not equivalent to the wings?

When I stand at a wind turbine and look at the shadow on the ground, the shadow is a bit slow at first then very quickly, etc. Very strange.
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0answers
6 views

Velocity Selective Coherent Population Trapping and recoil limit on temperature

I have read that it is possible to go under recoil temperature limit using VSCPT (Velocity Selective Coherent Population Trapping) and that this method is based on atoms trapping in quantum state in ...
1
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1answer
35 views

photon absorption by atoms causes heat?

I have came up with a weird doubt: photon absorption by atoms causes heat? I mean, I was always told that if the photon's frequency is the magic one, the atoms absorbs the photon and goes to an ...
0
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0answers
50 views

Speed of light, comparison of two light waves travelling side by side

okay so.here is setup of my question...say we have two observers A and A'..A is fixed to origin of coordinate axis x,y while A' is inside a hollow box (shown as rectangle MNRP) whose one side MN has ...
0
votes
1answer
27 views

Semiconductors light emission

Suppose a pure semiconductor, with a direct gap. If I apply a constant voltage to it the electrons will jump to the conduction band. So when I turn it off will it emite light?, because the electrons ...
35
votes
4answers
4k views

Do rainbows have ultraviolet bands and infrared bands?

We have seen that rainbows looks so colorful as we are only able to see only the visible light. But Do they also have ultraviolet bands and infra-red bands, that we are unable to see? I know someone ...
0
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0answers
21 views

Why does a circle of light form around a wire when a laser is pointed at it? [duplicate]

Referencing this video: https://www.youtube.com/watch?v=9Q_4SNbpBfo Why does a circle of light form? I've seen previous Phys.SE posts on this topic relating the answer to reflection, but I have ...
3
votes
2answers
58 views

Decoherence of a Coherent Beam

If retarding films (i.e. wave plates) can retard the electric components of light (based on the films thickness) without affecting it's direction, couldn't I use a retarding film of randomly varying ...
0
votes
2answers
70 views

Why do two beams of light pass through one another without interacting?

Why is it that if I have two torches, each shining rays in perpendicular directions at perpendicular screens, such that the beams cross, then the images on the respective screens are independent of ...
2
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0answers
21 views

Odd order of colour fringes around cloud

The other day I took this photograph of a thundercloud that moved between myself and the sun. Around the edge of the cloud there were some coloured fringes that I first took to be a variant on a ...
2
votes
2answers
39 views

How is the backlight in a LCD monitor dispersed equally?

How is the backlight in a LCD monitor dispersed equally? I mean are there any layers that disperse the light?
1
vote
2answers
68 views

Would passing horizontally polarized light through a varying width vertical slit allow you to measure the positional (x) amplitude of light? [duplicate]

I have found closely related questions on StackExchange, but (surprisingly) not this exact question. Seems some answers say individual photons do not have amplitude, only when traveling with other ...
0
votes
0answers
25 views

Why the underside of an object isn't a different colour after light reflects off a different coloured surface

If you were to place a blue plate in front of a green background and shine a light at the blue plate. The light that hits the blue plate would reflect the blue wavelength and when the reflected ...
1
vote
0answers
11 views

Polarization in LCDs why the light need to be polorized twice? [closed]

In Lcd Screens there is a prcess called polarization. Two question about it: 1. Why is it needed to pass the light through two polarizers ? 2. How des a pixel devide the light to three sub pixel and ...
0
votes
1answer
63 views

Is Lorentz transformation applicable of light itself?

I've just studied Einstein's Special Theory of Relativity and have followed most part of it. I was just wondering that whether the equations of Lorentz transformation are applicable on light? i.e. can ...
0
votes
1answer
74 views

Is it possible to produce coherent light with a thermal source? [closed]

Coherent light means monochromatic light and alle waves have the same phase difference. This is given for laser, where the resonator is a potential box and the outgoing waves have the same phase ...
0
votes
2answers
55 views

Frames of reference and why are they different

Here is a quote from "The Elegant Universe" by Brian Greene. Imagine two countries that have been at war are sitting down to sign a treaty ending hostilities while traveling aboard a train that is ...
2
votes
1answer
36 views

Filming light in slo mo

So I was thinking of a cool video I could make when I thought of filming a video of me turning on a light. I thought that if you film yourself turning on a light and slo mo that video enough times ...
1
vote
1answer
21 views

Relation between temperature and black body radiation

How can one derive the amount of light as well as the shortest wavelength of the emitted light from the temperature of an object due to black body radiation? Shouldn't the amount of light emitted ...
2
votes
1answer
88 views

If atoms are mostly empty space, why doesn't light pass through everything?

Atoms are mostly empty space, and although I now understand why matter doesn't pass through other matter, why don't photons pass through the empty space of the atoms? Is it the same sort of idea as ...
1
vote
1answer
30 views

Do the mediums decrease or increase the speed of light? (source to target) [duplicate]

If sun is the source of light then is it possible that the speed of light might increase depending on the mediums its going through or its not possible.
3
votes
0answers
52 views

Fastest path of light [duplicate]

Fermat's principle of least time says that light always takes the fastest path to any point. So how can light know which is the fastest path without taking all the paths first?
-2
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1answer
78 views

Are we working in the double slit argumentation with destructive interference arguments?

Stimulating water with two long straight bars one could produce linear waves. Having the right distance between the bars and the correct frequency of the steady system we get in the middle between the ...
21
votes
3answers
3k views

Why isn't the color of a molecule a combination of the colors of its component atoms?

I was watching a documentary on youtube regarding Quantum Physics when it introduced the wavelengths of light emitted. Did a bit more research over the internet and I believe I understand the gist of ...
1
vote
1answer
75 views

How do I convert lux to lumens

Overview... I'm a novice in the very basics of light physics and calculation between various units. I'm sure this is a very simple problem to those who know the process. And, before we continue, this ...
12
votes
2answers
3k views

Is true black possible?

Black is the absence of light because it absorbs light, but when we create black paint or black objects, light is always reflected, either in all directions in matte or smoothly in shiny black ...
6
votes
0answers
110 views

Why can I turn light red or blue by holding my finger up to it?

This is a difficult phenomenon to explain. Imagine you have an opaque object partially covering a very bright light source, for example, an object held up against the sky. The left hand diagram is ...
2
votes
1answer
35 views

A half covered lens

Let's say there's an object in front of a convex lens. I have a piece of paper behind the lens at the right location such that it will the lens will form an image on the paper. The object is ...
0
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0answers
43 views

Relativity - Diffraction Of Light

Following thought experiment. Inside a rocket, right in the middle, we place two lasers pointing in opposite directions. Both emitting the same wavelength. The Left wall of the rocket is L1 while ...
1
vote
1answer
42 views

Is redshift possible if relative speed is 0?

Since we are in a galaxy that is moving 1M mph, and the speed of light is constant, is redshift affected by whether you are facing toward or away from the direction the galaxy is moving? Suppose you ...
0
votes
2answers
104 views

Could time dilation bend the path of a photon? Does time dilation have a refractive index?

The main question I am getting at is, does time dilation have a refractive index? What I mean is, if I were to shoot a laser past a black hole, would the laser's path "bend" strictly from time ...
2
votes
1answer
43 views

My glasses seem to be polarizing the light when they want. What is happening?

When I put the glasses on and I look at my computer monitor and I turn in a certain angle everything becomes black. When I do it on my laptop screen though I need a different angle. Finally when I ...
1
vote
2answers
65 views

Do rainbow shows spectral lines?

A spectral line is the electromagnetic radiation emitted when the electron jumps from higher orbital to a lower orbital of an atom. Water mainly consists of two elements namely hydrogen and oxygen, ...
0
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1answer
52 views

Converging light

Imagine that we emit a light pulse. As is the nature of light, it will expand. However, light is affected by gravitational fields and light has its own. Therefore, will the light converge given ...
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0answers
17 views

About atomic transitions

I accomplished my homework but it opened a whole pandora's box of things I do not quite understand, so I would appreciate help. In x direction linearly polarized light excites atom transition from ...
3
votes
3answers
67 views

Principle of Sufficient Reason on light travelling in straight line

I was reading a book Laws and Symmetry by Bas C. Van Fraassen I found that there is an argument for arguing that light travel in straight line: Leibniz's reconstruction of these arguments goes ...
1
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2answers
92 views

Speed of light and perception

So I'm reading a book called "The Elegant Universe" and here is a part of it Imagine two countries that have been at war are sitting down to sign a treaty ending hostilities while traveling aboard a ...
0
votes
1answer
37 views

Can high-power LEDs remotely control a whole room? [closed]

Let's say I have 4 appliances in rectangular based room of about 60 square meters with white walls. The appliances are using infrared receivers with a filter of 38 kHz. Would it be possible to apply ...
2
votes
2answers
84 views

Is light a particle with EMF or does it travel in wave? [duplicate]

Is light a particle which has a electromagnetic field around it OR does the particle itself travels in a wave like motion? IS it just the EM field which moves in a wavy motion like ripples? (Please ...
1
vote
1answer
14 views

Do electric sinusidal waves rotate 45 degrees too when light pass through a hollow cylindrical magnet or just the sinusoidal magnetic waves do that?

Do electric sinusoidal waves rotate 45 degrees too when light pass through a hollow cylindrical magnet or just the sinusoidal magnetic waves do that?
0
votes
1answer
28 views

Saturation current vs frequency

In the photocurrent experiment, if the intensity of light is kept constant, but the frequency is slightly increased, what's the effect on the saturation current? I think saturation current should ...
1
vote
1answer
54 views

Can a one-way mirror effect be reversed?

I understand to get the effect of the one-way, one side needs to have light to produce the mirror, leaving the darkened side with the ability to see through. I would like to know if there is a way to ...
0
votes
0answers
25 views

How can three consecutive polarizing filters let any light through? [duplicate]

Say I have three sheets of Polaroid in series. I also have an unpolarized light source. Let the first sheet of Polaroid be set up vertically so that only waves oscillating in the vertical direction ...
3
votes
1answer
59 views

Why does light “expand”?

The "opening" for light to travel out of a flashlight is circular. Why does the light shine on the objects the flashlight is pointed at over a much larger surface area than the surface area of the ...
2
votes
1answer
40 views

Why does sunlight cause colors to fade?

If you leave something outside, its colors seem to inevitably fade or bleach due to exposure. Is this due to UV absorption? What sort of mechanism causes this - is it that man-made dyes deform on a ...
2
votes
1answer
67 views

Pinhole Camera Problem!

I was reading slides of a university course and in one of the slides it says 1 Eyes/cameras can’t have VERY small holes because that limits the amount of entering light 2 and diffracts/bends ...
0
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1answer
76 views

Determining the path of a light ray

Let's consider a ray in the plane $xy$. Let the refractive index be defined in any point of the plane with the function $n(x,y)$. In time $t=0$ the ray is located in coordinates $(x_0, y_0)$ and its ...