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.

learn more… | top users | synonyms (3)

0
votes
0answers
7 views

How does the area of illumination affect the numerical aperture / optical resolution of an optical system?

I have been reading an optics paper in which they designed a microscope with the following setup. A light source passes through a small pinhole, illuminates a sample, which then forms a diffraction ...
0
votes
1answer
25 views

What kind of other light sources can disturb the detection of LASER

My project objective is to detect different lasers , for example Laser Range Finder: pulse width 10ns and repetition rate is ...
1
vote
0answers
11 views
45
votes
5answers
22k views

Why glass is transparent?

Once I asked this question from my teacher and he replied "because it passes light", "and why it passes light" I asked and he said "because it is transparent". Same question again, Why glass is ...
2
votes
2answers
133 views

Can you use infra-red goggles (or similar principle) to see through mist and fog?

As per title really... fog is obviously quite opaque to visible light yet transparent to radio waves. What is the range of frequencies at which fog is opaque, and is either end of this range at a ...
1
vote
1answer
16 views

Michleson Interferometer fringe shift

I have a problem with interferometer fringe shift. I am learning it from my physics book. In the book, it is written, "As the L1 (Displacement of moveable mirror) is changed, the pattern of ...
12
votes
3answers
1k views

What causes atoms to have their specific colors?

I understand that light (color) is part of the electromagnetic spectrum, and that it depends on what wavelengths are reflected/absorbed. Though what property of an individual atom gives it its color? ...
12
votes
3answers
627 views

What gives things color? [duplicate]

I know that color comes from things not absorbing a certain wavelength of light, but what property gives something color? Like what property of copper atoms makes copper as a whole brown, or cobalt ...
3
votes
2answers
60 views

Time-coherency of “incoherent” light

Even "incoherent" light as the one of a light bulb has some coherency, and would interfer in the double-slit experiment (even if more blurry because the different wavelengths don't trigger the same ...
0
votes
3answers
93 views

Is this true about low-light/one photon at-a-time double-slit interference?

I've consistently noticed in pictures of double-slit interference when very low-light or one photon at-a-time is used, that there's lots of "stray" photons detected in the areas of destructive ...
3
votes
1answer
36 views

Why do some elements burn different colors? [duplicate]

I have a torch lighter and it makes a green color when the flame passes over the metal in the center. What on the molecular level would a flame change color although there is no difference in ...
18
votes
3answers
4k views

Can something without mass exert a force?

I am something of a dilettante in physics, so please forgive me if the answer to this question is painfully obvious. The question is simple, can something that theoretically has no mass exert a force. ...
7
votes
2answers
191 views

Why is condensed milk glowing green under UV?

Teeth, nails and also сгущёнка (condensed milk) are glowing green when exposed to black light. What do they have in common? Is it a specific luminophore substance?
-1
votes
0answers
28 views

Why use a LED light source in an experiment of fluid mechanics?

There are two main kinds of light sources used in the experiments: Laser and LED, which are very different in energy consumption as well as the wavelength range. I guess the reason is related the ...
0
votes
0answers
7 views

Why emulsions do not show Tyndall Effect?

The particles in an emulsion are large enough than that of solution, but why emulsion does not show Tyndall Effect?
14
votes
3answers
3k views

Is true black possible?

Black is the absence of light because it absorbs light, but when we create black paint or black objects, light is always reflected, either in all directions in matte or smoothly in shiny black ...
0
votes
0answers
25 views

what happens to light when it passes through a magnetic field of infinite feild strength? [on hold]

Light has both particle and wave nature.If light is to be considered as a particle what happens to light when it is passed through a media of infinite magnetic intensity and infinite field ...
0
votes
1answer
69 views

Backing out of interactions: Does physics account for such a thing?

Does physics account for interactions between light and matter ever being "not completed" or backed out of? Here's what led me to the question. In learning about interference in light, I ended up ...
1
vote
1answer
29 views

How does sunlight undergo interference as shown in the video?

As far as I know, for interference to happen in a double-slit experiment, the light source should be coherent and monochromatic. If that is the case then how come sunlight undergo interference and ...
0
votes
1answer
29 views

Why is it easier to make inks which show up on white paper than on black? [on hold]

Not sure if this is a Physics question, but... Why is it easier for inks to show up on white paper than on black? You can get "special" inks which print solidly on top of black surfaces, but your ...
10
votes
1answer
49 views

Glowing light around my shadow during sunrise

This morning I was jogging when the sun came rose. I was in the middle of wheat-fields and noticed that there was a glow around the upper part of body's shadow on the fields. At first I thought that ...
1
vote
1answer
55 views

How does Compton scattering demonstrate particle over wave behavior?

Why is Compton scattering thought to demonstrate light's behavior as a particle over that as a wave. I'm interested in the thoughts at the time of Compton, but also how it contradicts current theory ...
28
votes
3answers
4k views

Why aren't all objects transparent?

I know that for an object to be transparent, visible light must go through it undisturbed. In other words, if the light energy is sufficiently high to excite one of the electrons in the material, ...
1
vote
0answers
18 views

Fresnel Diffraction

In fresenls treatment of a plane wavefront when the aperture is infinty then intensity on the screen must be equal to the intensity of incident wavefront. Intensity comes out to be 1/4 times the ...
1
vote
2answers
78 views

How come lenses alter the path of photons?

From what I know, photons are theorized particles and believed to be massless (just energy) and travel at the speed of light. How come a lens, which is an object made of atoms, can bend a light path? ...
12
votes
4answers
5k views

Why does adding red light with blue light give purple light?

Our eyes contain 3 photoreceptor cells (cones) to perceive three wavelength ranges of light. Here is a visual representation of the wavelengths by these receptors (S, M and L). So if we have light ...
0
votes
0answers
17 views

Find the ratio of maximum intensity to minimum intensity [closed]

Question: Two coherent sources of intensity $10Wm^{-2}$ and $25Wm^{-2}$ inference to form fringes. Find the ratio of maximum intensityb to minimum intensity. Progress: ...
0
votes
1answer
20 views

Finding Intensity of light incident on a photodiode

Given a halogen lamp(9500lumen,500W) at a distance d from a photodiode. How can I find the intensity of light incident on the photodiode?
0
votes
3answers
89 views

Create a laser from sun light

I have read on wikipedia the basic theory behind laser. A photon passes through an excited electron which then produces the exact same photon. Light is bounced off mirrors to create more photons. Is ...
9
votes
4answers
2k views

How many percent of the visible light reaching the Earth are from other stars than the Sun?

How many percent of the whole visible light reaching the Earth are from other stars than the Sun? Is it maybe 0,5 - 1% or is my guess already too much? I am interested mainly in visible light, but ...
7
votes
2answers
213 views

Bending of light - photon's inertia instead of mass

Using classical mechanics, the formula for gravitational attraction is $$F = G\frac{m_1m_2}{r^2}.$$ This formula does not work for photons, and we need to use Einstein's theory of gravity to ...
0
votes
1answer
75 views

Can light break relativity's reference frame? [closed]

I have fairly little experience with relativity and physics in general, so I might just be missing something, but I do often ponder how the universe works. My understanding of relativity is that ...
0
votes
0answers
5 views

Height of a point in a plane given a measure of luminance

Context Assume a left-hand rule coordinate system and X points right, Y points up, Z points out. I have a camera facing perpendicular to the X-Z plane in the negative Y direction. I have 4 ...
0
votes
0answers
20 views

Mirror shake emulation for the light

Is there any way to simulate mirror shaking? Final goal is to make send light beam to the mirror and get reflected beam the same, as it happens if mirror is vibrating. Mechanical vibration is limited ...
1
vote
0answers
18 views

Light bulbs Flashing on when disconnected

For the 2nd time I've had a lightbulb flash on in my hand after removing from the power socket. The first time the overhead light in my hallway was out for a couple of days before I got around to ...
0
votes
1answer
52 views

Is fire more harmful than a phone?

I have read somewhere that the higher the frequency of electromagnetic radiation, the higher the damage it causes to your body, and visible light has a very high frequency in comparison to microwave ...
-2
votes
1answer
50 views

Is the rate of light emissions actually the frequency of the light?

I am confusing with the concept of frequency in the context of Doppler effect studying SR. The Schutz says, if the source emits pulses more frequently, then the observer would see the lights not only ...
0
votes
3answers
148 views

Light-Particle Wave Duality

There is a lot of reading to do on this to fully understand it, but without doing that reading is there a short explanation as to why and how light behaves as a wave and a particle?
0
votes
0answers
24 views

Help with uncertainties! pixels and pinholes [on hold]

Okay so I have kind of a strange problem but I'm really not sure how to solve it. As part of my physics coursework I conducted an experiment to find the optimal size of aperture for a pinhole camera. ...
3
votes
1answer
41 views

What is “Condensed Light”?

It is mentioned in this article It seems to be a Bose-Einstein condensate of some kind, but it is not exactly clear how one can create a BEC with just photons Light consists of tiny indivisible ...
6
votes
2answers
2k views

Why doesn't the magnetic field polarize when polarizing light?

If the magnetic field doesn't polarize does it follow the electric field path of propagation? or does it vanish?
1
vote
0answers
40 views

Can 2 photons make up the same colour as another photon?

So, my question deals with the excited electron shown above. (1st diagram) This electron can return to its ground state by either of two ways. One of the ways involves the emission of 2 photons. ...
0
votes
1answer
22 views

Blue light is reflected, red is not. What happens to other visible/non-visible light?

The problem says: The certain film on the glass reflects blue light of wavelength 480nm, but does not reflect any red light of wavelength 640nm. 1) If we say that it reflects blue light but no red ...
3
votes
1answer
31 views

Explain Sun Glare

Above is a picture that I took just before the sun set. Notice the prominent red blob to the left of the sun. Can anyone explain the phenomenon that creates superimposed shapes and blobs in images ...
0
votes
0answers
54 views

Cherenkov Luminescence Imaging, Cherenkov radiation,

Is it possible to see glowing from Thin Layer chromatography (TLC silica gel on Aluminium) when we image it by IVIS spectrum (no radioactive source)?
1
vote
2answers
248 views

Is light getting another color when travelling through a prism?

When white light travels through a prism the speed of this light is slowed down. Now there is a relation between speed of light, frequency and wavelength. So when a red light of 700nm enters a prism ...
0
votes
1answer
46 views

Basic question about light

My understanding is: when light hits an object, it can do one of three things: transmit through the object, be absorbed into the object, or reflect from the object. However, I have also learned that ...
0
votes
1answer
42 views

Is it scientifically possible to stop a screens polarization by adding a layer? [closed]

Back story: At work we deal with confidential data, however our desk layout does not allow for screen privacy. We do not a privacy screens and are not allowed to take apart our screens. In searching ...
0
votes
0answers
18 views

Is there a limit to the frequency of light? [duplicate]

I am assuming that light frequency would eventually be limited by Planck distance and/or Heisenberg limitations. Could this frequency ever be approached in practical terms?
0
votes
2answers
488 views

How to use a magnifying glas or any lens to enhance small light power?

I am currently trying to amplify a tiny amount of light so that a photodiode will recognize it. In order to amplify the light I thought about using a magnifying glass since I got to know that such ...