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 is diffraction at a maximum when slit is of order of wavelength? [duplicate]

Diffraction is maximised when the slit is of the order of the wavelength of the wave being diffracted. Why does this happen? Is there a visual way to show this (animation or picture)?
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What has a greater effect on diffraction - increasing wavelength or reducing slit width? [closed]

Diffraction from a slit increases when wavelength increases or slit becomes narrower. Which one would have a greater effect though - changing wavelength or decreasing slit width? Looking for an ...
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How exactly do we know light is precisely the EM radiation in the form of transverse wave?

What experiment proves light is a transverse electromagnetic wave consisting of both electric and magnetic fields? Can we somehow produce visible light by some kind of antenna or other mechanism that ...
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Why is central fringe twice the width of all others in single slit experiment? [duplicate]

The interference pattern shown on screen after a single slit diffraction experiment shows the central fringe is twice the width of all other fringes. Why does this happen? Looking for an intuitive ...
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1answer
218 views

Intensity graph for laser double-slit experiment?

For incoherent light sources, they are passed through a single slit first. The interference pattern of the single slit then modulates the intensity of the double slits' interference pattern. But what ...
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1answer
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Why does intensity decrease from the centre fringe in slit experiments?

This happens in double slit, single slit and grating experiments with light. Looking for an intuitive answer.
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Intuitive explanation why wavelength and slit width affects fringe width in single slit experiment?

I know the formula that shows that wavelength and the fringes' widths are directly proportional in a single slit experiment, but is there an intuitive explanation for this? What about an intuitive ...
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2answers
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Intuitive explanation for slit separation affecting fringe separation?

I know the formula which proves fringe separation is inversely proportional to slit separation in the double slits, but is there an intuitive explanation to show that as slit separation increases, ...
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Why does the single slit in Young's Double slit experiment need to be narrow? [duplicate]

I've read in many places that it's to do with illuminating both double slits by diffraction, even though the interference pattern on the screen would be an overlap of different interference patterns. ...
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Hydrogen discharge tube emission spectrum different from emission during burning

In "How is it possible some substances burn with an invisible flame" it is stated that light emitted from burning hydrogen is almost invisible, more precisely: You say that hydrogen flames are ...
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High velocity sparkler

A "sparkler" (hand-held) firework is designed to emit light and sparks. Best seen in the dark, one can whirl it quickly to create a continuous loop. If one could increase the whirling speed ...
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Does recombination of light in a glass slab happens in the same way like in Newton's inverted prism experiment?

I know that refraction is due to different speeds of different wavelengths of light. So, How can those colors recombine to form a beam of white light (since different colors have different speeds)? ...
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Does most matter emit and/or reflect visible EM radiation more than EM of other frequencies

When reading this SE Q&A: Would visible light still be in a separate classification if we saw "colors" in a different wavelength? I started to wonder if we evolved to see the visible ...
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Would visible light still be in a separate classification if we saw “colors” in a different wavelength? [duplicate]

Basically im asking if there's anything special about visible light other than the fact that we use it to see colors. If we saw in another wavelength, would it still be possible to see colors like we ...
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If different wavelengths of light have different speeds, how can they move together as a white light in air?

My question is with respect to Newton's experiment of using two identical glass prisms [in which one is inverted with respect to the first one]. When he allowed all the colors of the spectrum to pass ...
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1answer
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How two light sources with identaical illuminance can have different luminance?

My question is regarding a slide from a lecture we had about photometric units. Namely, after being introduced to the luminous flux ($lm$), illuminance ($lx := \frac{lm}{m^2}$) and luminance ($\frac{...
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Any scientific basis behind Thoreau's Stacked Shadows?

In Walden Henry David Thoreau states, Sometimes, when the ice was covered with shallow puddles, I saw a double shadow of myself, one standing on the head of the other, one on the ice, the other on ...
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Calculate irradiation from a LED lamp

I am working with cell culture and I want to irradiate a 96-well plate with a single color led lamp (let's say the peak is at 450nm). It's just a test, so a rough estimation would do. I've been ...
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Why does an image seem smaller through a pinhole when viewing with human eye

I was chewing gum when I took the Trident gum wrapper and rolled it into an open cylinder with a diameter of about 1.5mm (give or take 0.15mm). When I look through the gum wrapper (I have to put it ...
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Magnetism and light [duplicate]

We know that magnetic field lines tend to form a closed loop! we also know that light is a electromagnetic wave so it has an associated magnetic field with it, at any instant $t$ the $ B = B_{0} \sin (...
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3answers
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Why do black bodies in thermal equilibrium with their surroundings only emit in non-visible regions of the electromagnetic spectrum?

This question is a follow on from my previous question; Under what conditions can a body be approximated as a black body?. This question is also about one specific part of an answer given to this ...
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Does the distance between light sources and detectors influence the result of beam splitting experiments?

I have this experimental setup in mind: Here, the paths between L (light source) and D1/D2 (detectors) have exactly the same lengths. Normally, this would give a 50% chance of photon detection at ...
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Which of the following phenomena are responsible for rainbows?

Which of the following phenomena of light are responsible for the formation of a rainbow? 1) reflection, refraction, dispersion 2) refraction, dispersion, total internal reflection 3) ...
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Difference between primary and secondary rainbow

A secondary rainbow is dimmer than a primary rainbow. A primary rainbow is seen as a result of two refractions and one total internal reflection. A secondary rainbow is seen as a result of two ...
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Opposing Laser Beams Turns One Laser Off

When I send two separate laser beams directly into each other one of the beams goes completely out. These are inexpensive 5mv red diode lasers. What’s happening inside the laser to make it “turn off”? ...
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3answers
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How can this circle light cast a triangle shadow? [closed]

A friend of mine sat in the lobby of a local hospital and noticed that the circular ceiling lamp cast a triangle-shaped field of light / shadow (depending on how you look at it I guess). How is this ...
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What is the Origin of the chromaticity matrix used here?

I found the method to convert RGB values to XY coordinates using chromaticity matrix like this R, B, G -> R', B', G' -> X, Y Image of matrix: https://www.dropbox.com/s/89ys0tizskyv8eu/equations.png?...
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5answers
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Confused about what a wave is [closed]

When a wave of something, let's say light or some electromagnetic wave is given, I am confused because I do not understand if shape of a wave represents projectile of it or some value that possess at ...
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Optimizing hue of diving camera lenses

The goal is to understand the optimal hue of a diving camera lens based on ocean depth (and other factors). Solely judging by products offered in the market currently, I'm able to get a rough idea. ...
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What if there are two paths of least time? [duplicate]

I’m reading Fermat’s principle of least time from the Feynman lectures. And the following question popped. Suppose we have a medium whose the refractive index is a (continuous) function of the ...
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2answers
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Is A Photon A Wave Or Does It Emit/Create A Wave?

In my search for more clarification about photons being a wave or particle, I found a response here Photon's create waves that said that photons don't become a wave but rather create a wave. This ...
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Photons and visual light

So far as I understand photons are particles of energy that are produced when an electron moves down an orbit. That emitted photon bounces off of objects and because of the evolution of our eyes we ...
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Understanding wave particle with respect to time? [duplicate]

I am trying to understand how one photon corresponds to EM wave in time domain. If I hypothetically try to detect the EM wave at a particular position in space where a photon passes. How long will I ...
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Why Speed of light in vacuum remains constant? [duplicate]

I know that the speed of light remains constant irrespective of whether the light source is moving or not. But it's very difficult for my brain to visualize it. Light has dual characteristics, i.e. of ...
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Do photons actually slow down in a medium, or is the speed decrease just apparent? [duplicate]

Some places I've read flat out say light actually slows down in a medium, some say the speed decresae is just apparent but not real and that the photons still travel at the constant speed of light. I'...
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How is water athermanous?

My textbook says that water is an athermanous substance i.e. the type of substance which does not transmit any incident heat radiations. But how is that true since water is transparent, light that is ...
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1answer
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LED flicker vs human perception

I have read this question: https://mechanics.stackexchange.com/questions/43070/why-do-the-headlights-of-supercars-looking-flashing-on-video where cdunn says: So when you slow it down, you're ...
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How to picture wave nature of light? [duplicate]

I am about to start learning about light, having some knowledge of electromagnetic waves. I know an accelerated charge produces changing electric field which produces a changing magnetic field and ...
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1answer
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Lunar surface brightness

If the Moon is visible against a clear blue sky with a lux value of around 30,000 does it stand to reason that the lunar surface must be brighter than that?
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How can hydrogen spectrum be monomode (focusing on the lowest emission band)?

Consider you have an hydrogen atom. This atom can emit light under spontaneous emission for example, but the light it will emit will only be at some very specific frequencies: https://en.wikipedia.org/...
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Why don't appear all objects to be white?

When you shine light on an atom, it absorbs some of the wavelenghts; the rest determine its color. However, as far as I've understood, the absorbed wavelenghts exite the electrones moving them to a ...
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Dual Nature of Light Explanation Please [duplicate]

I am a high school student and I have studied that light has dual nature, i.e. wave nature and particle nature. So, how can any matter can posses two different behavior at the same time. Can we ...
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Are there elastic materials that are transparent to infrared light?

I am working on a device that I want to be encased in an elastic membrane to allow for articulation and water resistance. This means that all sensors must be inside the membrane. The membrane must ...
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1answer
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Why do atoms become unstable on higher energy levels?

In spectroscopy, atoms absorp light of specific wavelenghts that move the electrons to higher energy levels. The atom becomes unstable at some point and re-emits these wavelenghts to get to its ...
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1answer
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Emission lines vs the color of an object

As far as I've understood, the color of an object depends on which wavelenghts from the more or less "white" sun light it reflects and absorbs. I think that an atom can only absorb the light that has ...
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1answer
78 views

Photon travelling in a loop

I am wondering how my concept of light is flawed. Am I right in supposing that when I look at a star the light that I see is only the specific photons which enter my eyes? That means I never see the ...
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1answer
93 views

Human colour perception – summary needed

I am a graphic designer and I really want to have knowledge about human colour perception but the longer I am looking for and the more I read the harder this topic seems to be. Physics is not my ...
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1answer
48 views

Weight gain of prism due to light passing through

When a beam of light passes through a prism parallel to the base of the prism, the light slows down and hence its wavelength decreases. This, in turn, increases its momentum. Does this change in ...
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Shadows cast by Venus

How and why would a shadow on earth cast by Venus differ from one cast by the Sun or Moon? My thinking is that the shadow would be much fainter because less light is being blocked. Also, I think it ...
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What is responsible for colour of sky seen from ground vs space?

If short wavelength of light such as blue and violet scatters more by air molecules in our atmosphere at noon time along the equator but our eyes can only see the blue sky due to biology, then what ...

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