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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Could something theoretically observe the first light in the Universe?

Light travels at 299,792,458 meters a second. If you look at something that is 299,792,458 meters away, you're observing light from 1 second in the past. If an observer's distance from a light source ...
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Explaining light distribution trough a gap using waves and Huygens principle

According Huygens principle when a light wave goes trough a gap that is so narrow that only one wavelet can pass, it would spread out in all directions like in this image: (image from https://en....
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Reasons for mechanical wave inversion? [duplicate]

General idea (with strings): When a wave in a string in transmitted through 2 different media, a part of it is inverted and a part transmitted. 'Rules:' If a wave enters a region where the wave ...
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Peculiar Question: Can Sound travel through particles of Light?

It is a thought Experiment. Imagine a box that is lined on the inside with 100% perfect mirrors. Shine some light into that box and seal the box. The light will bounce back and forth between the ...
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If both violet light and red light was incident on the center of a semi circular block, and refracted, would they have the same refraction angle?

As the violet and red light have the same speed in air, with the incident angle being less than the critical, with the violet light and the red light coinciding on each other, (like on top of each ...
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What is the color of viral particles?

I read today on twitter that because COVID-19 particle is very small (<100nm) and visible light wavelength is larger (>250nm) the virus has no "colour". I know that some molecular bonds vibrate at ...
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How to calculate amount of reflected light from a retro reflective tape at a distance

If retro-reflective tape is reported to be 1000 cd/lux/sq m reflective at some angle, how much of initial light can be measured at some arbitrary distance? That is if I shine a 5mW laser beam at the ...
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4answers
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Electrons emitting photons. Real life example?

In highschool we are taught about Bohr's atom model and how electrons emit light/ photons when transitioning from a higher energy orbit to a lower energy orbit. First question Where does this ...
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Two positions of the convex lens for a fixed object-screen separation

Explain why, for a fixed separation between the object and the screen(i.e., d + d' is fixed) there are two positions of the lens at which the images formed on the screen are in focus (clear images or ...
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How can I make sense of the way (screen) colors are generated? [duplicate]

OK here is some common knowledge I have from the net: a computer screen has 3 constituent colors of red, green, blue. To make all spectra of stuffs it just combines them. We also know that red is ...
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What happens to light (waves) when it falls into a room?

For my project that includes to design an ideal window for studios and housing i need to know the science behind what happens to light that falls into a room. I know that the light rays, to some ...
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Why doesn't the orange light filter appear bluish if it transmitts orange and reflects or absorbs all other frequencies?

I was going through the absorption and reflection phenomenon of light and this question struck my mind as I was walking through the light filters. Why does orange filter not appear bluish if it ...
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Easiest way to achieve low divergence beam coming out fiber

So I have a green (I plan to swap it with 940nm IR) LED shining the other end of an optical fiber and I want to produce a 5mm spot at 5cm. The conventional way to achieve this would be with a lens but ...
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What kind of information does light carry so that brain can “see” shapes and distances of objects? [duplicate]

I know that we actually see with our brain in a way that eyes only absorb the incident light upon them and they transform some sort of information to the brain and the actual "seeing" is done by the ...
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How can a picture of a virus be taken when they are not even 300 nm (wavelength of blue light) long?

We cannot take photos of protons because they are not at least the size of the wavelength that registers into visible light. I see photos of Coronavirus in the news everywhere where there is a clear ...
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How to use convex lens to magnify image without inverting

From my knowledge, convex lenses magnify and invert light rays that pass through it. So is it possible to use a second convex lens to make the magnified inverted image into a magnified upright image?
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Conduction band energy level under illumination

I am new to the field and my apologies if its trivial question. Consider a semiconductor having valence and conduction band at certain energy level. When it is illuminated with photons having ...
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Bubbles (water) are transparent, then how can they produce white light in mass amounts?

Bubbles (water) are usually translucent, and transparent too. In the field of optics, transparency (also called pellucidity or diaphaneity) is the physical property of allowing light to pass ...
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Why does an overlap of atomic orbitals in a solid cause a continuous emission spectrum? [duplicate]

A given explanation for a light bulb's continuous spectrum of emitted light was that energy levels in solids overlap, therefore all energy changes can occur. How can these changes occur? If an ...
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1answer
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Order of coloured bands of light: red, blue, green, orange, red, violet, green, and violet

I am currently studying the textbook Modern Optical Engineering, fourth edition, by Warren Smith. Chapter 1 presents the following diagram and explanation when discussion interference and diffraction: ...
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1answer
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Why is the two-term form for the Cauchy equation sufficient?

The general Cauchy equation for the relationship between refractive index and wavelength is given by, $$n = A + \frac{B}{\lambda^{2}}+\frac{C}{\lambda^{4}}+...,$$ but this is often approximated to $$...
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Must a rainbow's observer also be able to observe the sun?

I think I may recall sometimes a rainbow going away when a cloud comes between myself and the sun. I know that the appearance of the rainbow is location dependent. But do we need the sun, rainbow, ...
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how much information can beam of light can have in unit area? Can it have entire Earth's image? [closed]

Can one have a big lense in distant Galaxy where he can see everything (like humans walking and so on..) that happening in Earth? (Though there is a delay that's not important)
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Radiant Intensity

Radiant intensity is power per unit area and area being perpendicular to propagation of energy. Moreover, intensity varies inversely with square of distance. My question is if a beam of light is ...
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Is there any relation between turn on voltage of LED and the colour emitted?

It is evident from the above V-I graph that longer the wavelength of the light emitted lower is the turn on voltage. I know that turn on voltage is voltage required to have significant current that ...
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Mirascope Holograms

So I just realised that 3d hologram fan projectors are now a thing, and the quality looks quite good (search Ashata 3d hologram fan projector). However, an inherent problem with them is that the image ...
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A question about supernova (explosion decay curve)

In the third paragraph of this article: http://www.astro.ucla.edu/~wright/tiredlit.htm It talks about supernova decay and how a 20 day decay would appear to be a 40 day decay at a distance that has ...
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Can white light have two spectral peaks?

I was looking at a graph on the receptive ranges of the 3 types of color sensitive photoreceptors in us humans, and I had the idea that if we place only two peaks at the right places, we'll be able to ...
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4answers
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How can an electromagnetic wave behave as a particle?

Light is an electromagnetic wave and it possess both properties of a particle and wave. Looking at the image I can imagine how it behaves like a wave. However, I'm not sure how it can behave like ...
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If we had a good enough eyesight would we be able to see atoms and the fuzziness of the quantum world?

If our eyes had enough precision and calibration to see hundreds of thousands smaller scales than we do, surely our brains would also need a major tuneup to process it. But could our classical body ...
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Factors affecting Diffraction

I know that the larger the wavelength, the more the diffraction. However, I have a few questions. Is the diffraction more when the wavelength is equal to the gap size, or when the wavelength is ...
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Why is the ocean darker when it is windy?

There are a lot of questions and answers on this site about ocean color, but none of them addresses my question. I have found this too: https://science.nasa.gov/earth-science/oceanography/living-...
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Why the rays do not continue in a straight line when passing through a prism?

How does the lightning that is not going through a rectangle know? a ray that passes through a rectangle, continues in a straight line What happens to a prism made of retangles of different lengths? ...
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Does intensity of light change during refraction?

As frequency of light do not changes during refraction does intensity of light also change during refraction
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Big Bang most outer edges [closed]

If we can experience or see the beginning of the universe - i.e. see the Big Bang through devices - then can we perceive or see the most forward edges of the big bang racing outward?
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What determines how transparent a material is?

Every time light hits a material, both reflection and refraction occurs. How does a material determine how much light gets reflected/ refracted e.g. glass vs silver? So far what I could find is light ...
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1answer
92 views

Does anyone know what this equipment is?

Im a teacher and found this equipment clearing out my science storage room. Any idea what it is used for? Thanks!
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What decides the color of a flame?

Flame color can in part be decided by metal emission spectrums, that I know. But supposedly, the color could also be affected by the heat of the combustion, black body radiation. I’m wondering how ...
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Why can't light pass certain materials but Magnetic and Electric fields can

If I shine some light on a wooden table it doesn't pass through. However, if I attach two magnets one above and the other one below the table they still experience a force that attracts or repels ...
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How can you draw the wavelength of a wave to show that when a slit is of the order of the wavelength diffraction is at a maximum?

I was looking for a diagram to show how when the wavelength of the wave is of the order of the slit width, then diffraction is maximised. The diagram is supposed to be an intuitive explanation for ...
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Is the discrepancy in universe expansion in the speed of expansion, the rate that the speed is changing or both?

Is there a simpler way to describe the latest discrepancies or problem with the expansion of the universe. Does the rate of expansion consistently get faster and faster? I was reading this and had ...
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How can you show with a diagram that diffraction is at a maximum when the slit width is equal to the wavelength?

Usually a diagram will be given like this But how can you show with a diagram that diffraction can be maximised when the slit width is of the order of the wave's wavelength?
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Which would keep you cooler? A black canopy tent or a white canopy tent?

I was outside recently at a function and they had two colours of canopy tent set up: black ones and white ones. I was wondering which one would be cooler to sit under. The white one would reflect the ...
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Flicking a ruler (Camera optics)

A while ago I found this post on reddit which showed a ruler vibrating differently depending on the light: https://www.reddit.com/r/blackmagicfuckery/comments/ccymjq/...
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Polychromatic propagation of EM wave

Say I have a continuous light source emitting a flat light spectrum $\hat G(\nu)$ centered at $\nu_o$ with bandwidth $\Delta \nu$ (i.e $\hat G(\nu)=rect((\nu-\nu_o)/\Delta \nu$) ) and want to see its ...
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A question about rayleigh scattering

Is it possible for a ordinary sphere, say 1 cm in size to experience rayleigh scattering when it encounters radio wave?
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Does light travel in curve lines in free space?

I read in https://www.sciencemag.org/news/2012/04/light-bends-itself that some scientists have found a method to make light travels in curve without any external influence using Airy Function. I'm ...
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Single-slit Fraunhofer diffraction within finite baffle/barrier

Many standard expositions of Fraunhofer diffraction from a single slit (such as here: https://en.wikipedia.org/wiki/Diffraction#Single-slit_diffraction) assume that the slit is situated in a baffle or ...
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1answer
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Why does “bulk” yellow ink look red?

A transparent blue inkjet cartridge looks deep blue, a red one looks deep red, but a yellow one looks red. Tea also looks yellowish when it's shallow and reddish otherwise. Red is another colour, a ...
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To calculate wavelength, is a double-slit experiment or diffraction grating experiment better?

Which one would give the most reliable results and why? Even though in grating experiments you don't have to judge where the centre of a fringe is, wouldn't there be less fringes/principal maxima to ...

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