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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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1answer
48 views

Can we measure the speed of light in one direction?

I'm sorry if this is a dumb question. Recently I was learning that it's impossible for us to measure the speed of light in one direction. We can only measure it in two directions and we assume that it'...
0
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0answers
12 views

What's the difference between twisted light and light of circular polarization?

Circular polarization: https://en.wikipedia.org/wiki/Circular_polarization Orbital angular momentum of light: https://en.wikipedia.org/wiki/Orbital_angular_momentum_of_light From point of view, ...
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2answers
45 views

Is snow falling too fast or too reflective to produce rainbow?

Imagine millions of water molecules suspending in the air starts to turn into snow, I like to know the exact reason why we cannot have snow bow, is it due to the speed of each snow falling very fast ...
0
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1answer
56 views

Does the worldline of light depend on the frequency?

My Question is: If 2 rays of light are emitted with different frequencies from the same spacetime point, does an observer see them in the same worldline? I know that the worldline of light behaves ...
2
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1answer
20 views

White Light Interferometry [on hold]

I have arrived at a way to produce Arago’s spot with a quality white led flashlight. How would I go about writing a small educational paper on this? And, most of what I have seen on the web uses ...
0
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1answer
34 views

Is there a way to make an “unseeable monitor” without modifying a computer's hardware? [on hold]

What happens if you remove the polarization filter from a computer monitor? shows how to make an "unseeable" monitor from a LCD monitor, i.e. one that requires special glasses to view. I was wondering ...
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1answer
29 views

Why not anything like spontaneous absorption?

I understand that the idea of emission or absorption cannot be incorporated in the framework of non-relativistic QM. We need QFT or relativistic QM to explain the creation and annihilation of ...
1
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1answer
107 views

Why are my interference patterns completely out of phase?

DIY physics enthusiast here doing a double slit eraser experiment at home with a laser pointer, double slit diaphragm, and few linear polarizers (horizontal at one slit, vertical at the other, +/-45 ...
3
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1answer
38 views

How can we see incoherent light at all if waves interact? [duplicate]

If we assume that a monochromatic source of light produces waves with uniformly distributed phase differences then the sum of all those waves should be zero and thus also the intensity?
0
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1answer
4 views

Opacity of ionized/non-ionized gases

In which state is matter more opaque to radiation? I'm talking about gaseous vs plasma. I know that opacity is a function of frequency in general, but I thought that, since a non-ionized gas has more ...
1
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1answer
21 views

Does the distance between the slits, in the double slit experiment, affect the pattern displayed?

Does the distance between the slits affect the pattern displayed? I want a pattern where light parts and dark parts are equal, and I don't want the light parts to be bigger than dark parts.
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0answers
43 views

Predicting the Frequencies of Visible Light [closed]

Why can't the Standard Model predict the frequency range of visible light; which must rather be inferred from measures of wavelength? Given that QFT is a gauge theory in which, since the fields are ...
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0answers
22 views

unusual questions regarding controlling polarized light with LCD shutters

1) Is it correct to assume that if a light is already polarized one of the polarizers on the LCD shutter itself is not required to be present to selectively block it? 2) Is it correct to assume that ...
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2answers
43 views

Can an invisible neutron star exist? [duplicate]

Basically a neutron/quark star that approaches it's Schwarzschild radius but doesn't surpass it. Its gravitational force is great enough to not let light escape from it, but not great enough to become ...
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4answers
68 views

Can light radiation pressure change its own path

Well i have seen that light creates radiation pressure Can two light waves coming from two different direction change each others path?
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2answers
78 views

Will any charge oscillating in space create an EM wave?

Would it be correct to say that any charge oscillating in space (regardless of the spacial amplitude) at a given frequency will emit an EM wave of the same frequency? related: What change in an EM ...
0
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1answer
24 views

Why does certain clear plastic have an inner glow?

A type of plastic used in packaging for tamper resistant seals appears to have (what I can best describe as) a purplish inner glow under sunlight, and perhaps other bright light. In the image below, ...
2
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1answer
42 views

Does polarized light reflect in the same polarization?

If vertically polarized light hits a linear polarizer aligned at a 45 degree angle from the polarization of the light, my understanding is 50% of the light will pass through and have its polarization ...
0
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1answer
46 views

How does reflective Heads Up Display (HUD) film work?

I've been seeing this reflective HUD film more and more. It seems to let you look through it, but reflects the brighter parts of a display. The end result is similar to a video game where you get a ...
2
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1answer
37 views

How is the diffraction (or interference) pattern in this photo explained?

I noticed the above photo on a website (https://www.aapt.org/Programs/contests/pc09full.cfm?Meeting=SM09&Category=Natural&Placing=44). How the pattern can be explained bothers me for some time....
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0answers
7 views

Relation between critical angle between media different in optical density and their refractive indices?

The law states that: Sine the critical angle between two media = relative refractive index between 1st & 2nd media = absolute refractive index of 2nd medium/absolute refractive index of 1st medium ...
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1answer
35 views

Is frequency of Electromagnetic wave it's intrinsic property?

I was solving a simple refraction problem where the wavelength and velocity of the sodium light needed to be calculated after refracting through glass from air. Now after calculation I found the ...
1
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1answer
45 views

Does it give sense to speak about field distribution of a single photon?

A Point source of light has radial symmetry. If the source gets attenuated so that only a single photon is leaving each hour, can I still argue, that the field of the single photon is radial but the ...
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0answers
23 views

When light hits my glasses, each lens shows different color

So I was holding my glasses in a certain angle, and the light source is directly above it. When looking through one lens, I see purple straight 'lines', and through the other lens the lines are teal....
3
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0answers
45 views

While flying over Rome we noticed that during sunset, there was a green color between the red and blue of the sunset sky. What causes it?

The picture has only been trimmed and not edited. The green is visible when the red or orange tapers off into the blue. Is this different from what causes the green flash? We were flying from Rome.
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0answers
34 views

Is light a 3-dimensional wave?And how is that measured?

I'm assuming the answer to the first question is yes, if I'm wrong, this will be an easy one to clean up. Forgive me is this is a stupid question. When thinking of light waves or particles as waves, I ...
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0answers
43 views

Creating light with combining $E$ and $H$ fields

We know that light is an electromagnetic wave. So if we take electric field $E$ and magnetic field $H$, combine them perpendicular to each other, and make them oscillate harmoniously, would it create ...
6
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1answer
194 views

To what extent is the heat in the focal point due to visible light?

When focusing sunlight on a piece of paper, e.g. with magnifying glass, the paper will be charred and might eventually even burn (assuming low cloudiness). To what extent is the heat a result of the ...
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1answer
32 views

Reflection in a lake

Suppose there is lake. And a cloud is at a height h above it. The reflection of the cloud will be at the same depth in the lake as the height of the cloud or at the surface of the lake or at the base ...
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0answers
47 views

Difference between color and effective temperature

What is the difference between color temperature and effective temperature of a star? I have gone through the pages at wikipedia, but I still do not understand that. Can anyone please help?
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2answers
31 views

What happens if separation between slits is greater than separation between slits and screen in YDSE experiment?

I was studying Young's double slit experiment (YDSE) in which it was derived that the formula for path difference ($\delta x$) is : $$\delta x = \frac{y \cdot d}{D}$$ Where $y$ is the vertical ...
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0answers
40 views

Can light concentrated through convex lens be “cooled down?”

I've just been assigned this biology design project where I'm being tasked to create a device for maximizing "sunlight exposure" of crops and am unsure of this particular question, for the design of ...
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4answers
105 views

What change in an EM field is required to create an EM wave?

From here To generate a long wavelength requires an aerial of roughly one wavelength in size. and here One of the difficulties posed when broadcasting in the ELF frequency range is antenna ...
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2answers
42 views

How does scattering of light happen in atmosphere?

I know that the scattering of light decreases as inversely proportional to the 4th power of wavelength. But what happens at the atomic level? Does the photon get absorbed and re-emitted? Does the ...
67
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13answers
20k views

If visible light has more energy than microwaves, why isn't visible light dangerous?

Light waves are a type of electromagnetic wave and they fall between 400-700 nm long. Microwaves are less energetic but seem to be more dangerous than visible light. Is visible light dangerous at all ...
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2answers
23 views

Gravitational Lensing: Up, Down or Sideways

I have been reading about Eddington and his measurement of 1.75 arc seconds in 1919. What I am wondering is why was the measurement lateral? I picture a beam of star light entering a curvature of ...
1
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1answer
61 views

Why do cones require more light than rods?

The title says it. In our eyes, why do cones require more light than rods? Like is it because of the energy needed to change the state of the existing atoms, the molecules or what leads to the need of ...
19
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5answers
4k views

If perfect blackness violates the Uncertainty Principle, how isn't dark matter a violation?

In a recent tweet, Dr. Michio Kaku stated that perfect blackness would violate the Heisenberg Uncertainty Principle, i.e. every object must emit some radiation. I have two questions regarding this ...
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0answers
18 views

Superradiant scattering in ergosphere?

In a black hole there is a region of space where only energy can escape, the ergosphere. I read superradiant scattering can allow lights to gain energy much like gravity assist, what is the different ...
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2answers
50 views

What is the max amount of photons per second of the rods and cones in our eyes?

The title says it all. I just cannot find any information about this - I have tried for so long now. Therefore, I figured that I could reach out to some clever guys in this forum for help instead:) ...
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0answers
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Feynman’s Treatment of an Opaque Wall

First time poster. I’ve been reading Feynman’s Lectures on Physics, and I’ve just finished reading his treatment on diffraction. Feynman described a method of thinking about an opaque wall that was ...
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1answer
33 views

Missing link re: how does kelvin relate to temperature when talking about color temperature?

I am an electrician at a commercial electrical company. There is an in-house training program that posits the datum that when talking about the designations of color temperature for lights (for ...
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0answers
39 views

Do red lasers shoot longer than green ones?

I am aware of the fact that our eyes are most sensible to green color and therefore green lasers seem stronger than other colors when being scattered through the air. However, since red wavelength are ...
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2answers
65 views

Photons, light and electricity

Light is ultimately composed of photons. Photons are also force carriers of the electrical force. When an electric motor is turning it is photons which are turning it. What is the relation between ...
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1answer
87 views

Does light know the future? [duplicate]

As I understand it, if light is traveling at the speed of light, then from it's point of view space is fully compressed in its direction of travel. Does that mean that from it's point of view, light ...
2
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3answers
91 views

Does light get acceleration due to gravity? [duplicate]

When an object, say a ball, is attracted by the black hole it gets acceleration due to gravity. Suppose light is moving towards the black hole vertical to it... then does it gain acceleration due to ...
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1answer
63 views

Energy spacetime warping

If energy warps spacetime, then does light warp spacetime? And if special relativity says that things near the speed of light increase in relativistic mass, then does light have a relativistic mass? ...
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0answers
19 views

How does brightness affect color? [duplicate]

How does brightness affect the color of light? For instance, the sun might be yellow because of the blue scattering when the light travels through the atmosphere - but if you look at it, it seems ...
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2answers
40 views

How much light is needed to quality as possible dark matter candidate?

I know when scientists study dark matter they have already excluded light because of it's negligible effect on the galaxy and of course we are able to observe it directly, I am curious just how much ...
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2answers
108 views

Why does the sun always have some whiteness? [duplicate]

So the atmosphere scatters light on its way to earth, making the color of our sky. For example, when the sky is blue on a clear, sunny day, the sunlight appears somewhat yellow because the blue light ...