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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Why path of light is not visible in vaccum?

When light is directed towards our eyes we detect the source and locate it. In Huygen's principle it is said that every point on wavefront acts as source of secondary waves which again travel in all ...
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Does conservation of energy across “worlds” explain probabilistic filtering of photons?

We can set up a light filter and a light source such that angling the filter may block out some/all of the light. For example, with a certain filter angle we might see that $30\%$ of the original ...
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Why can't light travel three days into the future then transmit that information back to us prior to us arriving at that position? [closed]

Example: If a football game between the Pittsburgh Steelers @ Tennessee Titans will happen in 3 days Sunday 10/25/2020 at 1pm, why can't light leave today 10/22/2020 and go to where the Earth will be ...
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How do virtual images make any sense?

If the light meets behind the mirror, without really meeting, how is it even supposed to be interpreted. If two light rays never meet because they are diverging but they meet behind the mirror-which ...
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Horizontal stripes in a Prism Spectometer

While conducting an experiment in the lab, I used both analogical and digital spectometers to look into the spectrums of different light bulbs, one of which was a halogen bulb, which produces a ...
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How do wavelengths add-up?

If I have 3 LED lights of following colors and wavengths: Red 650 nm Blue 450 nm Green 550 nm All three are placed side by side and turned ON.. then what will be the wavelength of the combined light ...
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Can a beam of light, coherent or otherwise, conduct electricity, as does flame

Can a beam of light, coherent or otherwise, conduct electricity.
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How we feel (perceive) exact size of object through our eyes?

Light after getting reflected from objects gets focused on retina by our lens. The images formed on retina is small, which is then sensed by our brain and depending on distance we feel size of that ...
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3answers
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How electromagnetic wave was related to visible light? [closed]

The presentation I see in the textbooks goes something like this, Maxwell realized changing electric fields produce changing magnetic field and vice versa. Therefore, at least intuitively, one can ...
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What is the cause of these black spots on my chair? [closed]

Before voting to close this question please read the note section. I saw something really weird a week ago on my plastic armchair. There were a large number of black spots on my chair and I don't know ...
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Why do two different methods to calculate the path difference yield different results?

HCV Concepts(Physics) 17.26 Note that $\Delta$ means triangle Consider a point source of light S, which sends two rays of light of wavelength $\lambda$ (order of magnitude $10^{-7}$ m) - one to point ...
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If image formed by a plane mirror is virtual, then how are we able to capture that in a camera?

What I have learnt in school is that, we are able to see images behind a mirror(virtual image) because our brain assumes that the diverging rays that our eyes see, are coming from a point behind the ...
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Newtonian deflection of light and energy conservation

I was looking at some calculations of the deflection of light by the sun. However, there is something that I cannot understand. They usually express a relation $$r = \dfrac{p}{1+e\cos(\theta)} \qquad (...
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Can light take a (faster) detour?

I was taught that light tends to take the 'fastest' route. However, this made me wonder about the following scenario: Suppose the start and end point (source and observer) are at the edge of a large ...
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Polarization vector of chiral light

I was curious about the following point: let's say we have a left circularly polarized light wavepacket travelling from left to right. We will call its polarization vector $\epsilon_{L}$ while the ...
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1answer
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What is the reason for the appearance of absorption lines in the spectrum of light coming from the sun?

If your answer was that the sun's atmosphere absorbs some photons, I don't think so. Because the atom, after absorbing a photon, it seeks stability and emits an electron in a short time compared to ...
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How does an object's shadow pattern depend on size of light source?

A friend of mine unintentionally did an optics experiment. Basically, she wanted to cover her bedside lamp with a pattern of small holes, although she wanted the light projected from the bedside lamp ...
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Does light have a mass? [closed]

Could you please argue with work and gravity? Or however you like. I just don't get it. Thanks. A physics professor talked about if light had a mass, it should do work ($W=N\cdot m = \frac{kg\cdot m}{...
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In what way can I see the rotating hub and the bullet that has just been fired clearly with the naked eye?

In what way can I see the rotating hub and the bullet that has just been fired clearly with the naked eye? Some people say that you can place a shutter in front of your eyes, and then adjust the ...
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How is wavelength of light related to observability?

One of the things I learned from Heisenberg's Uncertainty Principle is that when you try to observe the position of a microscopic particle, you have to use a light of smaller wavelength (which implies ...
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1answer
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When (visible) light waves get reflected, why are the incident ray, reflected ray and normal coplanar?

I was told that when a wave of visible light is reflected (or refracted) then the incident ray, the normal to the reflective surface (or interface of two optical media) and the reflected and refracted ...
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1answer
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Looking for ideal calibration standards for UV / visible fluorescence

I am attempting to measure the fluorescence timing distribution (how much light is emitted over time from initial excitation) of a substance and I would like to use a solid calibrated sample (some ...
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Why does the solar corona appear white?

Look at this photo taken in France during the 1999 solar eclipse which I found on Wikipedia. Why does the corona appear white? It has a temperature of about $10^6\,$K so you would think that it would ...
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How does light, which is an electromagnetic wave, carry information?

We see an object when light from a source strikes the object and then reaches our eyes. How does light, which is an electromagnetic wave, gets encoded with the information about the object? Do the ...
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1answer
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How do we know that human eye reacts on frequency of visible light rather than on some other parameter? [duplicate]

This is a very basic question in optics: why the mathematical language we use corresponds to what we actually see. There are (at least) two ways to think of a decomposition of a visible light. One way ...
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Considering the history of microwave Background radiation, was it ever in visible range? When will it fall to be able to heat water like in our oven?

Please do provide assurance of what formula you used and that you did the calculations for the answer. Thanks. My back of letter calculation says that CMBR was never in visible range since it became ...
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How many images will I see if I am surrounded by 4 mirrors?

An image question got me today when I was reviewing image theory. With 1 mirror -- I see 1 image out of phase of myself. With 2 parallel mirrors, me being between them -- I see infinite images of ...
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Does the vanishing point of linear perspective occur when there's a 1-to-1 matching between the lights in the source, and the sensors of the observer?

Imagine we have a panel of lasers in a truly dark vacuum, together with a panel of sensors, facing each other, some distance apart. Further, imagine that the number of lasers within the light-panel is ...
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Single Slit Diffraction : Problem with the condition of diffraction

The condition for diffraction is that the effects of diffraction become more noticeable when the width of aperture is comparable to the wavelength, and from that we can say the spacing of fringes ...
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Photons confuse me [duplicate]

I'm not entirely sure if my question is valid or not but I'll ask it anyway. So my physics porf. told us the Photons are constantly in motion and they never come at rest and the sub-topics relating to ...
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1answer
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Specular Reflection of IR Light

I have started to use thermal imaging cameras more and more and realized that I can see the reflection of my self bouncing off of a glass window through the IR camera. When viewing it on my monitor, I ...
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Can we lock the light (photons) up inside a box? Why / Why not? [duplicate]

Imagine a box designed to make vacuum state inside. Is it possible for us to lock the photons up inside something completely enclosed?
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Why is blue light hardly produced in a filament light bulb even when the current through it is greatly increased?

We observe that as the current through the filament is increased, the filament gets hotter and brighter. Also the color of light changes from red to orange to yellow. It only gets till yellow-white, ...
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What is the difference between direct reflection and ambient reflection?

I am not in Physics major, and I wanted to know what is the difference between these two: direct light reflected for the first time (like an object reflecting the light coming from the sun). ambient ...
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How can light coming from the receding galaxies be stretched like matter?

Edwin Hubble discovered in 1929 that the universe in expanding and the light from the receding galaxies are red-shifted; their wavelengths become longer. How can light which is an electromagnetic ...
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$\rm Lux$ to $\rm W/m^2$ conversion?

For a physics project, I'm planning to investigate the relationship between the number of slits in a diffraction grating and the intensity of the central maxima. The light meter which I'm planning to ...
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What is the range of colors a lightning can produce?

What is different about the lightning to cause air to react in different colors? Rare in one thunderstorm but ball lightning has also been reported in different colors. How could one create a red or ...
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1answer
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Why is the colour of the texts written by inks appearing Yellowish and Purplish and not the printed one? [closed]

I was revising some of the concepts from my old copies and I noticed something really weird (might not be weird for others). The texts with black pen when seen from behind the page had some yellowish ...
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1answer
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Do gravitational lenses act as prisms?

Light creates gravity, and the greater the light's frequency, the greater this gravitational effect is. It stands to reason then that light of different colors would react slightly differently to ...
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1answer
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What does 'Normalized Solar Intensity' refer to in the diagram below

For the Value Axis (Normalized Solar Intensity) what does the value represent? Is it the Solar Irradiance rate normalized in a specific equation or is it something else?
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Is there such a thing as a white laser pointer? [duplicate]

I can't seem to find a white laser pointer for sale anywhere. Is it just me or is it somehow not possible to make it? I see only color laser pointers like red, green, blue, etc.
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Do gravitational waves change the color of light?

It stands to reason if gravity changes the color of light then the color will be affected by gravitational waves. My question is, when the waves pass, will the color change be permanent or will the ...
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Can a “lightsaber” be scientifically possible? [duplicate]

Can a lightsaber be made in real life? If yes, how can you make it? If no, why is it impossible to make it? I know there is another question on it, but I feel like I need better answers :)
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Diffraction of light (slit)

According to some books, diffraction occurs when there is an obstacle whose linear dimensions are comparable to the wavelength of light. This is true also for a hole or a slit through which the light ...
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Can a photon vibrate without any velocity or directional movement; Can it vibrate without moving? [closed]

I understand that light travels in a straight line unless gravity says otherwise. However, if it were theoretically possible to keep the energy in a photon without having any directional movement, ...
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Why fiber optic cables looks colorful?

I wanted to know why fiber optics look green or blue, isn't it that it uses total internal reflection, so light shall remain in it? I think may be it's not monochromatic.
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Spectra of cool cloud and hot clouds

So I’ve read that a hot gas cloud will emit light according the emission spectra of the atoms of the gas (I understand this in relation to energy levels). However, I then read that if we shine light ...
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Why does light bend at an angle when it passes through a prism?

i mean when the light go throw the prism it Deviates. At an angle and dissolves at the same time. Do prism atoms have anything to do with this? why it can't go directly in a straight line?
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Problem regarding the absorption spectrum of the sun

Some of the wavelengths of light that are emitted from the sun will be absorbed by atoms in the outer layer of the sun and also the atmosphere of the sun, and we see this as absorption lines in the ...
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That the laser hits the same point on the opposite side of the box implies it is moving faster than $c$?

In Greene's video: https://www.youtube.com/watch?v=2pV20KuDucs In the video Greene describes a fairly well-known thought experiment. A person is in a rectangular box floating in space with a laser ...

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