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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4
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2answers
473 views

Why do we use microwaves in microwave oven?

We know that any object above absolute zero emits electromagnetic radiation. So hotter the object shorter the wavelengths. In the electromagnetic radiation spectrum radio waves has the longest then ...
2
votes
1answer
20 views

How to build a MOKE (magneto-optic Kerr effect) magnetometer at home?

I'd like to build a magnetometer at home. The type does not matter actually that much but it should be doable at home. The MOKE (magneto-optic Kerr effect) magnetometer at least appears to use ...
1
vote
0answers
14 views

How is ink's color produced?

From https://en.wikipedia.org/wiki/Complementary_colors The pairs of complementary colors vary depending upon whether the colors are physical (e.g. from pigments), or from light. These change ...
1
vote
1answer
22 views

Refraction of light marching band analogy

When trying to understand the refraction of light when it hits a slower medium, lots of people seem to be enlightened by the 'marching band' or 'marching soldiers' analogy, which 'explains' that when ...
0
votes
1answer
25 views

Interference of waves

Every thing has a dual nature. So if we take waves(consider light interference) as particles, exactly what happens during interference (both constructive and destructive)? Can you explain in easy ...
0
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0answers
25 views

Can other animals see black differently? [on hold]

I am not sure if this is the right place for this question, but this is a debate that has been going on between two colleagues for days and I need a resolution because it's driving me crazy. So any ...
4
votes
1answer
62 views

Why “colours” of light are given in wavelength not frequency?

If I understand correctly, when a beam of (monochromatic) light passes through media of different refractive indices, its wavelength changes but frequency remains constant. Why, then, are colours of ...
0
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1answer
44 views

Has the knowlege of rainbows gained from snell's law ever been used in a practical way? [on hold]

So, I'm an AP physics 2 student at the moment, and I'm learning about Snell's law and refraction. Due to the changing speed of light (for these purposes; I am aware that C is constant) in water ...
0
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0answers
19 views

Why does the spectrum for deuterium show a weak line at H-alpha?

I was wondering why the spectrum for deuterium shows a weak line at H-alpha, the first line in the hydrogen spectrum.
3
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0answers
30 views

Beating the Diffraction Limit with NSOM

I am trying to understand exactly why we can beat the diffraction limit when using near-field scanning optical microscopy (NSOM). For those who aren't familiar with NSOM, check out this article: ...
0
votes
2answers
49 views

Models of light

As far as I'm aware, there are two different (and almost contradictory) models that describe the behavior of light: light as a wave (EM), and light as a particle (QM). From what I've heard, depending ...
1
vote
1answer
55 views

What happens if light is trapped between two points?

The image can explain my question In the image light is clearly trapped.Even if the mirror absorbs energy the light is continously being added, will there be enough force to break the mirror?
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2answers
39 views

Why doesn't the Sun appear green to our eyes?

The spectrum of the Sun as seen at sea level can be seen at https://commons.wikimedia.org/wiki/File:Solar_Spectrum.png so we can see that wavelengths around green to yellow are the ones that are the ...
0
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0answers
39 views

Does Gravity Act on Any and All Things in the Universe? [duplicate]

I'm studying physics, and the questions below popped up in my head. I learned that all objects on planet Earth fall due to the influence of gravity. A ball falls. A mug cup falls. A coin falls. ...
0
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3answers
150 views

Is purple in visible light?

This isn’t a duplicate. I read those pages, but those didn’t answer my questions. Please watch this. Does visible light consist of red, orange, yellow, green, cyan and blue? No purple? My definition ...
3
votes
3answers
121 views

Why most of physics is somehow related to light? [closed]

It seems that for the past 200 years, every physicist is concerned about light. For example : Newton's particle model, Young experiment, Photo-Electrict effect and Einstein's formula, Special ...
1
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2answers
57 views

Velocity of light

Velocity of light decreases as it enters a more optically denser medium. So how far can the velocity of light be reduced? Which object has the highest refractive index?
4
votes
1answer
41 views

Shadow of a ripple?

Suppose a stone is thrown into a pool of crystal clear water and its a bright sunshiny morning. You can observe a shadow of the wave in the bottom of the pool. Why does this happen? Is it due to ...
5
votes
1answer
105 views

What causes light to travel through a curved fountain of water?

Today I observed a tilted fountain spurting water upward (the water fell smoothly; no detectable turbulence). A colored light was shown upward into the water as it left its source. This light traveled ...
6
votes
1answer
790 views

Test whether a glass prevents you from getting your Vitamin D portion?

I work in an office with glass, which I believe filters the UV radiation of the sunlight. Is it possible to test if exposure to the light coming through the glass will supply Vitamin D for me as a ...
-9
votes
0answers
84 views

Theoretical model of the universe [closed]

Goodmorning, I have worked for some time now on a completely "new" model of the universe, light and stuff that matters. Will one soul on this earth read, really read, and understand my model? or at ...
-1
votes
0answers
40 views

we know that light travels in a straight line, but why? [duplicate]

Our observations indicate that light travels in a straight line, but why should it? If I were to travel along with that photon, my time would stop. There would be no past or future, so I reAlly ...
3
votes
1answer
42 views

Young's double slit experiment and intensity

I want to ask a question about double slit interference and the pattern that it produces on a screen (for example in Young's Experiment with a laser beam). I understand the reason that you see a ...
0
votes
2answers
114 views

Why is the spectrum of a blue flame the way it is?

In the spectrum of the blue part in a candle flame, there’s a violet emission at 432 nm due to excited CH* molecules (chemiluminescence). Why 432? Why not 400 or 500? There are emissions at 436, 475 ...
2
votes
1answer
35 views

How can shadows ever be sharp?

When I hold my hand underneath my lamp, the shadow my hand casts is crisp and sharp, meaning that the edges are well defined and not blurred. But according to Huygen's principle, shouldn't the light ...
0
votes
2answers
46 views

Why is there lightning where there are no clouds?

Recently my family and I went onto the balcony to observed the stars in the night sky. We started to see flashes in the sky and we realized that it was lightning (non fork lightning). I looked around ...
27
votes
4answers
4k views

Why are stars white?

That is may be a easy question, but I am not a professional. The sun is a star and when I look at the sun is usually yellow. Why stars in the night are white? I suppose is for the distance. What is ...
1
vote
1answer
39 views

How can a camera zoom & photograph the sun without damaging the lens?

I find Huge images of sun in google images, i doubt that if we zoom the sun's image by using camera, then definitely sunlight will also get intensified leads to lens damage nothing but acting like ...
0
votes
1answer
10 views

Saturation point of incident Light on an object

Since the color of objects depends on the parts of the visible spectrum reflected out and the remaining is absorbed; is there any maximum limit to which the absorption can take place? In other words, ...
30
votes
5answers
4k views

Is there an infinite amount of wavelengths of light? Is the EM spectrum continuous?

The electromagnetic spectrum is a continuum of wavelengths of light, and we have labels for some ranges of these and numerical measurements for many. Question: Is the EM spectrum continuous such that ...
0
votes
1answer
32 views

Red/blue shifting out of visible spectra

How fast would a white light (emitting only visible spectra) need to travel in order to red or blue shift so far its no longer visible? Are some stars completely invisible due to this effect?
0
votes
0answers
12 views

Is the link between shadows a refraction of the light? [duplicate]

When two objects in the sunlight approach, if you look at their shadows, they form a link when they are really close, is that an example of refraction? If so, is it the same as the refraction we see ...
0
votes
2answers
169 views

Light, being a probability wave, carries energy; does an electron wave also carry energy? If so, how?

The entity "light" behaves as a wave & particle. The wave is actually probability wave . That is, to every point in a light wave we can attach a numerical probability that a photon can be ...
3
votes
1answer
40 views

How to calculate the colour a human eye sees when looking at a light spectrum?

I have to do a presentation about colourants in Chemistry class (grade 12, advanced) and want to write a program that calculates and visualizes the colours of some simple molecules. What I need is ...
11
votes
2answers
391 views

Sun spectroscopy - Home experiment

We let the sun light run through a 5x3x3cm triangular glass prism and we examined the formed 'rainbow' in search of Fraunhofer lines. However, even though we looked close enough (even with a ...
0
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0answers
21 views

Generation of electromagnetic waves [duplicate]

I came across this while searching about generation of electromagnetic waves-Does this mean that if I vary the electric current following through a conducting wire, it will radiate electromagnetic ...
1
vote
1answer
31 views

Do photons have a spectrum like light when they are treated as waves?

If light can be treated as both a particle and a wave, are there things called infrared photons, or ultraviolet photons etc, as there are infrared waves, or ultraviolet waves? Or are photons just ...
0
votes
2answers
94 views

Are we feeling the sun's heat?

If I may summarize something I told a friend in a pub... "We don't get heat from the sun at all. Heat requires matter to move through and there's too much vacuum between the sun and us for any heat ...
33
votes
6answers
4k views

Where do photons go when they are absorbed?

The answer I usually get (and I'm paraphrasing here) is that they disappear and are instead absorbed as heat energy. But I find it hard to believe that the photon simply "disappears." Common sense ...
1
vote
2answers
120 views

The relationship between light and magnetic fields

I have two questions. Does light have a magnetic field? If not, can it be affected by other magnetic fields?
5
votes
4answers
329 views

Can we change a photon's frequency in mid-air?

Can we have a light source emitting photons in the infrared range and after, lets say, 5 meters, these photons become a photon in the x-ray range? The only way I know we can change a photon's ...
3
votes
2answers
86 views

Do light particle/waves have a frequency? [duplicate]

I sought the answer to the question about amplitude of light waves first, but I was actually thinking about whether the wavelength is the only property of a single quanta of light. I suppose direction ...
4
votes
2answers
321 views

Reflected and refracted light have same frequency as that of the incident light frequency. Why?

My text book says- When a monochromatic light is incident on a surface separating two media, the refracted and reflected light both have the same frequency as the incident frequency. Can anyone ...
8
votes
3answers
144 views

Why doesn't $ds^2 = 0$ imply two distinct points $p$ and $p'$ on a manifold are the same point?

Let's suppose I have a spacetime manifold $M$. Let $p$ be a point on my manifold. Now I move from $p$ to some other point $p'$. Presumably I should have moved some "distance" right? How can I speak of ...
1
vote
3answers
39 views

Frequency dependence of the speed of light in air

According to this link, the speed of light of different colors in a medium should be different. But if the refractive index of light in air is 1 then this means that the speed of light in air and ...
1
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0answers
33 views

Is this fine to think of light as the following? [closed]

Is light quantums (increments [photons]) of the electromagnetic waves which are synchronized by oscillations of electromagnetic fields
2
votes
5answers
195 views

White, is it a colour or absence of colours?

Our chemistry sir and we had an argument today at the lab, he says that white actually is not a colour, it is the abscence of colour, but we say that it is a colour and we gave the following point to ...
0
votes
1answer
43 views

How many foci does a converging or diverging lens have?

I thought this was a simple question but can't seem to find a direct answer. In ray diagrams with a converging or diverging lens, we always draw F (the focal length) on both sides of the lens. But ...
3
votes
1answer
84 views

How do photons carry information?

In cosmology it's frequently said that photons from the early universe carry information from that time. However, wouldn't they also carry data from later interactions? How do we differentiate ...
1
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0answers
62 views

Interstellar Movie: Black hole shown in the movie [duplicate]

In the interstellar movie, the black hole shown has a ring of light orbiting around it. From what I know, (correct me if I'm wrong) that light is unable to escape the gravity of the blackhole and ...