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.

Filter by
Sorted by
Tagged with
3
votes
0answers
35 views

Doppler effect of light

Doppler effect for light is created for relative motion . But shouldn't light always approach us at the same velocity 'c' regardless of the relative speed ?Then how does Doppler effect work ?
0
votes
1answer
76 views

What causes objects to appear “black”?

To my understanding, the reason objects appear of a certain color is because it is the color (in visible light) that is absorbed least by the electrons in the material's atoms, and the rest is ...
0
votes
0answers
27 views

Dispersion of Light Passing Through Prism [on hold]

Why is light absorbed and reemitted when passing through a prism? How does this relate to dispersion due to a prism, in which higher frequencies are refracted at greater angles?
0
votes
0answers
33 views

How do materials absorb light

I'm curious how light is absorbed in materials. From what I understand, when an electron absorbs a photon, it gets excited to an energy level that is higher than the level it's in and the energy ...
2
votes
0answers
52 views

Physics behind rays of light in the photographs taken in the darkness

What is the physics behind these rays of light visible in the photographs of objects that emit light? What justifies their shape and amount of rays? Very well known effect in a sense, but I did not ...
0
votes
1answer
28 views

What happens to frequency during dispersion?

I'm a bit confused about what happens to frequency during the dispersion of white light passing through a prism. I understand that when a light wave is travelling in one medium, velocity is constant ...
1
vote
1answer
80 views

What would a lens-less world look like to us? [closed]

The images we perceive through our eyes are formed by focusing the incoming light with the eye's cornea and lens. The information is "captured" by the retina and then transmitted to our brains through ...
1
vote
0answers
15 views

Optimal paint for UV fluorescence?

If we assume that a light source with 365 nm is the optimal source for how strongly we perceive UV light when it hits a UV fluorescent surface, what would be the optimal colour to paint such a surface ...
0
votes
1answer
30 views

Optical Logic Gates using Polarisers

I am trying to build an optical logic circuit using the horizontal or vertical orientations of light as the two binary states and laser as the source. Before I ask you my question I wanted to first ...
0
votes
0answers
45 views

How to explain this thumb experiment?

Close your thumb to your eyes and align your eyes, thumb and moon. Then focus your eyes on your thumb and watch the moon behind your thumb. You will find that the moon becomes small! Remove your thumb ...
32
votes
8answers
8k views

Why aren't rainbows blurred-out into nothing after they are produced?

I understand how a prism works and how a single raindrop can scatter white light into a rainbow, but it seems to me that in normal atmospheric conditions, we should not be able to see rainbows. When ...
0
votes
0answers
24 views

What about X-ray production supports the particle nature of light? [on hold]

Apparently the production of X-rays supports the particle nature of light, but how?
0
votes
1answer
37 views

Is all light of the same intensity?

In an experiment like the Young's Double Slit, if you shine any different wavelength of light, will the maxima peaks be of the same height? How is the intensity of light changed?
1
vote
0answers
68 views

When two photons annihilate each other through destructive interference, where does the energy go? [duplicate]

When two photons annihilate each other through destructive interference, where does the energy go? Perhaps this is only answered by ‘wave type’ questions and answers? Does the conservation of energy ...
3
votes
1answer
57 views

How much heat do colors absorb?

A common grade school experiment is to compare how hot different materials get in direct sunlight. See examples here, here and here for example. The premise is generally two identical objects of ...
0
votes
2answers
17 views

Is there a way to precisely measure or infer the color of a material from a distance (~2m)?

I've recently started working on a graphics/SLAM project. I've encountered a problem that requires the measurement or inference of the color / spectral reflectance (and ideally albedo) of points on ...
1
vote
2answers
61 views

Can an observer perceive a single source of light as multiple sources because of curved spacetime?

Is it possible that some of the stars and galaxies we observe here on Earth are actually replicates of other stars and galaxies we are observing from different angles because of curved spacetime? Let'...
0
votes
0answers
271 views

What is the most likely cause for this strange lighting at sunset?

Yesterday's sunset was a little bit weird in several countries (Saudi Arabia, Egypt, Kuwait). Here's a video & picture, in case it wasn't clear enough it felt as if everything was being lit by a ...
0
votes
1answer
46 views

How do I explain the below phenomenon I am seeing along the edges of my eyeglass lenses?

I am near-sighted. Here is the phenomenon: I stand in front of a light source that is situated on the ceiling so that it reflects off my eyeglass lenses and appears circular. It is a white light ...
0
votes
1answer
27 views

Formula for blurring out a grid of holes

Place a camera lens with focal length f_l mm and camera sensor size w mm and h mm behind an ...
1
vote
2answers
33 views

Why doesn't the energy of an incident photon impact the angle of reflection?

Note that I am not asking why the angle of reflection is what it is. That is a different question. I am asking why the energy of the incident photon does not affect the interaction in question at all,...
0
votes
0answers
40 views

Why do out-of-focus light sources disappear from view backwards?

If you defocus your eyes and look at a source of light – say a street lamp – and then slowly move an opaque object in front of it, the light disappears 'backwards'. (Note: this effect is most apparent ...
-2
votes
1answer
48 views

What is the frequency of white light? [duplicate]

We can see white LED light after a combination of red, green & blue LED together. Then what is the frequency of white light? Whether it lies between 380 Hz - 700 Hz? There has to be a frequency ...
1
vote
0answers
27 views

How to find distance given candela values on a coordinate system?

Consider this diagram: Let's say that some lamp at 1.5D, 2R has a luminous intensity of 35,000 cd. I want to find the maximum distance at which this lamp can put 5 lux on the road. I understand ...
0
votes
0answers
27 views

World line of a photon from a distant galaxy in the $\Lambda$CDM model

The title is pretty much explaining the question: I am used to the graphs of Einstein-De Sitter model horizons: But then I don't understand 1) Are we using this kind of diagrams also now to ...
0
votes
1answer
22 views

Change the color of a LED Display (Make it appear different)

I want to know if it is possible to make a red L.E.D. display appear a different color, at least theoretically, but ultimately for a D.I.Y project. Based on answers to this question (How do color ...
0
votes
0answers
24 views

How is the optical conductivity for a single photon related to normal conductivity?

Planck argued that light energy is carried by photons. The electric optical conductivity for an electromagnetic wave is classically derived. How does this conductivity look like for single photons?
0
votes
0answers
22 views

Electromagnetic waves & observer effect [duplicate]

So I’ve been doing some research & realised that they done the double slit experiment with large molecules and the molecule behaved as a wave , so does this mean that all matter is really just a ...
1
vote
1answer
36 views

Relativistic beaming/ Aberration effect derivation

I'm researching applications of relativistic beaming and I want to derive a formula for the aberration effect but I am stuck (I am off by a factor of 1/c). Here's what I have: Consider a star in its ...
0
votes
0answers
32 views

Energy absorbed by a medium if X-rays pass through it

Obviously light-matter interactions are extremely complicated, but I’m trying to get a general estimate. Say I have a beam of X-rays, passing through a medium - say water - of a finite thickness and ...
0
votes
2answers
66 views

Snell's law and Fermat's principle

I have read this sentence on a book about the Snell's law of refraction, referring on a ray that passes from air ($n_1=1$) to glass ($n_2=1.55$): "Snell's equation can be derived from Fermat's ...
-3
votes
1answer
57 views

Bending a Laser Beam [closed]

We can bend a Laser beam by varying the refraction coefficient of the air. We can bend a Laser beam by dispersing into the air small particles that have the same effect on the Laser Beam and small ...
0
votes
3answers
70 views

Do waves of light overlap?

Hopefully I can phrase this question so that it can be understood and not appear to be entirely uneducated. From what I understand when light hits an object it reflects that light toward you. Let's ...
1
vote
4answers
144 views

Is there 100% pure white? [duplicate]

Is it possible to have an object 100% pure white without sky blue or sun color tinting the pure whiteness of the photons reflecting/deflecting off an object? Are there any lights that can produce pure ...
3
votes
4answers
142 views

How can light be made up of particles?

In order to explain photoelectric effect, Einstein suggested that light is made up of photons, but I don't understand how could this have made sense when you know that light is an electromagnetic ...
0
votes
0answers
5 views

Why are Raman lidars and Rayleigh-Mie lidars operated at those specific wavelengths for aerosol study?

A study of several Atmospheric lidar stations around India shows that in order to study properties of aerosols, all Rayliegh-Mie lidars are operated at 532 nm, and Raman lidars are operated at 355, ...
2
votes
1answer
47 views

How do LCDs vary light intensity?

What exactly happens when an electric field is applied? Say we're dealing with a TN LCD, in a 'normally white' mode. With no voltage applied, the orthogonal grated plates cause the director of the LC ...
0
votes
3answers
52 views

How are images in a telescope finite rather than just a point? [duplicate]

I understand that light passed through the objective lens of the telescope produce an image that is real and inverted, and have a height which is measured as the distance between the focal point and ...
1
vote
0answers
38 views

Relativistic Aberration Formula Derivation: looking for a hint

The literature on relativistic beaming / doppler beaming is scarce, so I hope the community can shed some "light" on this topic. I want to derive a formula for the phenomenon known as relativistic ...
0
votes
3answers
46 views

Would fast oscillating charged object emit light?

If I were able to mechanically oscillate an electrically charged object at frequencies of 430-580 THz, would the object emit light?
0
votes
3answers
63 views

How far can light (packets of photons) travel on earth or atmosphere?

How far can light travel on earth or in the atmosphere? Or, if I want to be more specific, how far can one photon travel until it disintegrates? I assume gravitational pull and other effects cause ...
1
vote
2answers
89 views

Why does violet light bend the most? [duplicate]

When white light passes through a prism, refraction occurs and it splits into its seven constituent colours. If the spectrum is obtained on a screen violet light appears much more bent than red light. ...
0
votes
4answers
111 views

Line of vision - If I cannot see someone, is it possible that they can see me?

Imagine I'm on a rooftop of a building. If I am lying down behind a wall and cannot see someone standing on another building- no matter which direction I look, is it possible that they can see me?
1
vote
0answers
31 views

Possibility of Star Wars style holograms [closed]

We’ve all probably seen those neat little hologram projectors in franchises like Star Wars, are holograms on the level we see them in Star Wars possible? If so, what are some approaches to this type ...
0
votes
1answer
21 views

Can iridescence be produced with a monochromatic light source?

An iridescent substance appears to change color based upon the angle of observation, and I assume this is because the substance reflects different frequencies of light at different angles. My ...
1
vote
3answers
109 views

COSMIC ACCELERATION

Please forgive a probably naïve question from a lay person. I understand that galaxies are all moving away from us in every direction we look. And for any given distance the speed is the same. And ...
-1
votes
1answer
48 views

What do we really mean by the word “light”? [closed]

Does the term "light" refer to any electromagnetic wave or just the visible spectrum?
0
votes
2answers
32 views

Angles of Refraction,Internal reflection and incidence

First ill ask my question in brief and then ill elaborate it below... Theoretically is it that internal reflection occurs within a solid sphere(which is considered to be the denser medium) if and ...
0
votes
2answers
31 views

What do you see when you are inside a transparent conducting material?

Lets say that there exists a transparent conducting material. Lets carve a cavity in the meat of the conductor big enough for a person to stay in. There exists an external electric field. But, We ...
1
vote
2answers
101 views

Are all the photons we observe from the sun disappearing beyond the horizon only reflected ones?

On a boat in the ocean at the equator (earth rotating 28km) watching the sun dip below the horizon (4.7k away) do we see any photons that were emitted directly from the sun (8 minutes ago) or are they ...