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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Can mirrors reflect destructive lasers or do they absorb the energy and would get destroyed themselves?
There is much talk of using lasers to bring down drones. That talk is followed by talk of protecting the drones by surfacing them with mirrors.
Would that work or does light falling on a mirror ...
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$r_1+r_2= A$ in prisms
In class we derived a result which said that the sum of the 2 angles of refraction in a triangular prism $r_1+r_2$ is equal to the angle of the prism $A$. The proof goes like this
Over here, it is ...
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Specular and diffused reflections
reflectivity of a mirror is very high but on a microscopic level no mirror is perfectly smooth so all the reflections must be diffused and we should not see any perfect reflection so how do we see ...
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What is this vector notation? For linear retardance calculation
Consider:
I found this formula in https://doi.org/10.1364/BOE.426653 (NLM), a paper titled: Stokes polarization imaging applied for monitoring dynamic tissue optical clearing.
The formula is for ...
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What's wrong with this One-Way Speed of Light experiment? [duplicate]
I can't tell what's wrong with it.
Imagine the wheels of a car, jack the car, put a sensor on one wheel, a laser on another, start rotating, with enough speed the sensor will start to detect the laser ...
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Why is there only one angle of incidence that gives minimum deviation in prism?
On plotting the angle of deviation vs the angle of incidence for a prism, we find that the graph dips only at one point. It is this result that is later used to prove that for minimum deviation to ...
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Explanation about black holes
As a newbie I was reading the book "The Theory of Everything", and came about these two paragraphs which I just don't understand:
I had already discussed with Roger Penrose the idea of ...
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How do i calculate change of momentum when I send a photon in the direction of travel
Say a spaceship is traveling at a certain velocity v (>>c) and it emits light from the nose of my spaceship in the direction of travel. The speed of light is finite and hence there should be a ...
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Poisson spot amplitude
The equation
$$
U(P) \propto \int_0^{2\pi} \int_0^{\infty} g(\rho,\theta) \exp\left[ \frac{i\pi}{\lambda}\left(\frac{1}{z_0} + \frac{1}{z_1}\right) \rho^2 \right] \rho \, d\rho \, d\theta
$$
or the ...
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Optics: How does lens prescription work for near vs. far distance?
I don't have any physics background aside from intro physics so apologies if my question sounds very shallow.
If lens power is based on focal length, but our eyes adjust its focal length based on the ...
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Why do the 'colors' of liquids in differently sized glass cylinders appear similar despite varying absorption rates?
For some liquids, such as cooking oil, I have observed that when filling two glass cylinders (with lids) of different diameters (e.g., one with a 5 cm diameter and another with a 10 cm diameter) with ...
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How does light absorption work for solids and liquids?
I've studied in my physics class, absorption and emission spectra for gases or more "spread out" molecules like what is done in atomic absorption spectroscopy (learnt that one in chemistry). ...
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How many photons in a light ray from the Sun to Earth?
Just trying to get an order-of-magnitude estimate - I feel like there must be a number, as photons are discrete entities, but the only way I thought about solving this question was to divide the Earth ...
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Why do objects appear more obvious in a dark room when we indirectly look at them?
I am currently in my room and it's dark (of course not an absolute darkness as you know yourself).
When I look directly at the ceiling lamp which has been turned-off for half an hour, I can't see it. ...
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Why does the inner wall of a smooth glass have seemingly rings when viewed from above?
I was looking at my glass and I found these rings. Are they reflection of the upper circle of the glass?
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Why does pouring water have a slightly different color when viewed from above?
I have noticed when I view a hose pouring water the color of water slightly changes when looking from above compared to when looking from the front.
Also, the same thing applies when you pour water ...
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Why lights create this kind of concentric patterns?
Inspired by a youtube video, i was trying to do the double slit experiment at home using a single hair and saw the interference pattern.
Then i wondered what would happens with many hairs and when i ...
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Why do colored lights produce colored shadows?
I found in this site that if we use a set of colored lights we'll have colored shadows. But why is that?
As far as I know a shadow is where there is no light. So why isn't the shadow that is produced ...
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How would red (frequency) shift work for sound waves on the surface of a balloon?
Imagine an expanding balloon with a source of vibrations, in the fabric of the balloon, on one side (pole), and a microphone on the other side (pole). We would expect the sound to be 'red shifted' ...
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Characteristics of melanin based semiconductors built from polydopamine
I am curious to know if the relatively newly developed melanin-based semiconductor materials made with polydopachrome have been able to create films or crystals which visually reflect blue, purple or ...
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Predict color of dye under a certain wavelength of light?
I am picking fluorescent dyes to be put under a UV of known wavelength and would like to be able to predict approximately what color the dyes will appear under the light. I can request ...
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Is it possible to make real DIY microscope with several lens?
I have alot of small double convex 7 mm lenses and i have very small lens 4mm
And i have plano concave lenses all of them is small
I tried to combining them to get a magnified image and it worked when ...
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Density of photons in an expanding image?
This is a question from an interested amateur. Math welcome (as I or another may investigate it some day) but don't expect me to understand it in your answer.
Consider a star emitting light. In ...
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(A10) If light is an EM wave, can it interfere with electrons in a live wire, leading to a change in the wire's current?
Here's my question: If light is an electro-magnetic wave, with oscillating magnetic and electric fields, wouldn't light interfere with the free electrons flowing (slowly) in a wire, as the electric ...
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What does the sky look like from the moon?
From pictures taken on the moon, it appears that there are no stars visible in the sky, but I do not know if this is an effect due to cameras.
What is the actual appearance of the sky on the moon?
...
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Position of central maxima when source is not in line with the slit
If the source is placed at S1, the central maxima would be at the centre of the screen (in line with the slit).
However, if the source is shifted to S2, would this mean that the central maximum shifts ...
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Prism: full spectrum including UV + IR
When shining a white light source through a prism, one will see the spectrum of it—so a lot of colors depending on the type of light source.
However, I would also like to see the invisible part of the ...
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Why does a blackbody object emit light if it only absorbs light?
I have learned that a blackbody object only absorbs light and thus does not reflect any light. The blackbody object will, however, emit light, and none of this light is due to reflection. Where does ...
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Seeking Visualization Tools for Hypothetical Black Hole Concept
I have a idea I'd like to explore: If a black hole can bend light due to its immense gravitational attraction, could we imagine an 'inverted black hole'? In this hypothetical scenario, this object ...
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Apparent violation of laws of reflection for an inertial observer [duplicate]
I am actually having an introductory course in Special Relativity in which I was looking at the Michelson Morley experiment. And I have this silly confusion.
The setup for the Michelson Morley ...
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Why is the visible light spectrum different to a hue wheel?
The following problem has bugged me for a while, ever since I noticed it. On the Visible Spectrum Wikipedia, the following is the visible spectrum:
Now, in Photoshop, or really any colour picker, the ...
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Why rainbow colors are as they are? [duplicate]
There are handful of questions related to rainbow formation here already, but after looking into them, I feel that I must ask yet another one.
I did a little research on the subject, and most of the ...
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Where can I find tabulated data for reflectance per wavelength (for Cu, Ag, Fe etc)?
I'm looking for a tabulated data for reflectance per wavelength for various materials for the visible light range. I found only images so far. Are there any spreadsheets with the raw numbers?
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A friend of mine seems to believe that E=mgc. He believes that gravity and light are the same. That gravity is just photons not moving. Silly I’m sure [closed]
I don’t know how to frame the question because I lack understanding of physics. But it doesn’t make sense to me when he says E=mc2 is wrong or incomplete and that his formula of E=mgc is the ...
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Does refraction depend on the colour of light?
Consider passing red and yellow lights separately through the same interfaces and with the same angles of incidence.
Light of which colour will be refracted more?
This question was given to me. All I ...
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Why specifically is looking through a telescope at the sun more dangerous than the naked eye?
At first this seems like a stupid question: "Have you never used a magnifying glass on a sunny day?!"
But any lens will only ever make the focused image as intense as the target or weaker. ...
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Is there a physically-based model for atmospheric perspective color?
In the picture below, mountains farther away blends into the color of sky, this is "atmospheric perspective", caused by atmospheric scattering. This effect is also called "fog".
...
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If photons are massless, how are they reflected and blocked by something that has mass? Shouldn't they pass right through any object?
If photons are massless, how do they get reflected, blocked when something comes in its way? Shouldn't the particle just pass right through any object?
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Expansion and visibility of particles because of diffusion
A cloud forms as a point source containing a fixed quantity of
particles and then expands according to the diffusion equation. Let's
analyze how the visible size of the cloud changes with time. When ...
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Why does light interact with normal matter but not with other light?
Why does light interact with normal matter but not with other light?
Assumptions:
Light does not interact with other light at all.
Light does interact with other matter, i.e reflection/refraction.
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Why does the dust in the sky make the light shine more or in other words it is visible from far away?
Why does the dust in the sky make the light shine more or in other words it is visible from far away?
This image shows how light is scattered in dust particles]1
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Relativity on a massive bridge
Suppose there is a ridiculously large bridge, fixed at either end (light seconds long at least). The bridge is constantly under the influence of gravity. If the ends are severed simultaneously, the ...
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What is reason behind the curve shape of Rainbow 🌈? [duplicate]
We see rainbow 🌈 during rain but what excites me more that why always rainbow 🌈 are formed curve?
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Does passing through a colored medium cause light to become that color or to lose that color? Why is the atmosphere different?
It's well known the effect of Rayleigh scattering on the color of the sun, and it's explained several times on this website. Here's one of them. The summary of these explanations is, that when light ...
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How would we perceive light arriving to us from a distance source?
Imagine being in space 5 light minutes from the source of a beam of light. The source of the beam of light is initially switched off.
The light is turned on. When it is turned on you would see ...
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Why do sun emit light of different frequencies? [duplicate]
The sun emits white light, which is a mixture of light from all frequencies. Instead, it should have emitted a beam of light of the same frequency, as the source is the same?
So, can you please ...
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Why $\rm ZnO$ looks transparent?
I'm looking for the reason transparent of $\rm ZnO$ and found out nanoparticles of $\rm ZnO$ do not scatter reflected light
can I conclude like this: material can be transparent if pass light or ...
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Is it possible for photons to gain mass and interact with the higgs field? [closed]
If objects gain mass as they approach the speed of light, is it possible that as a photon "attempts" to exceed the speed of light it gains enough mass to interact with the higgs field ...
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What are the hex color code equivalents for the different classifications of stars?
Stars appear to be of various colors based on the visible light they emit. I am wondering if there is a hex color code that can be considered to be typified or average for the various classifications ...
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Is “imperfect black”, (anything other than a black hole or vacuum), actually a color?
Is “imperfect black”, (anything other than a black hole or vacuum), actually a color?
Nothing absorbs all light except for a black whole, or a vacuum which doesn’t reflect light. If we consider black ...
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