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.
Questions tagged [visible-light]
4987 questions
46
votes
6 answers
Is there a physical reason for colors to be located in a very narrow band of the EM spectrum?
The portion of the electromagnetic spectrum that is visible to humans are wavelengths between 380 and 750 nanometers.
I am aware that animals have different capacities than humans, but the EM spectrum where they see colors is very close, e.g. 300 -…
Nicolas
- 609
- 5
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42
votes
4 answers
Why can I see a diamond?
So a diamond has a energy band gap of $\approx 5$eV. If that is too much for visible light $\approx 1.6$eV to be absorbed and then it travels straight through a diamond.
Although, I still see a diamond. I know that when light goes through, there is…
Tsangares
- 712
32
votes
9 answers
Why can we see light further than it shines?
This is a question I’ve been thinking about for a while. If I’m standing in the middle of a straight road, during night, I can see a car coming towards me because of its lights even if it is kilometers away. Notwithstanding, the driver can not see…
Tchapo
- 461
15
votes
4 answers
What invisible flicker do different types of light bulbs have?
What waveform does the light coming off different types of artificial light sources have and (of course) what are the underlying physical reason for them?
I was inspired to ask this question because of several things I have been hearing…
Alan Rominger
- 21,047
13
votes
14 answers
Can there be black light? I mean is it possible to devise a machine that outputs darkness?
I understand there are various colours that light can have. But i was wondering why there is no 'black' light. What is the logical explanation for this? I mean I am expecting an answer that goes beyond mentioning the spectrum details. All I could…
ritwik
- 187
11
votes
2 answers
Why can we see the earth from outer space if the sky is blue?
As far as I know, the sky is blue because as light from the sun enters the atmosphere composed primarily of wavelengths of visible light. However, as the light happens across molecules of oxygen and nitrogen in the air, they have a small chance of…
QCD_IS_GOOD
- 6,710
11
votes
4 answers
Colors from a computer vs. colors from visible spectrum of sunlight
Observation:
So, I know that all computer screens are able to project many different colors by varying how they display the RGB (Red, Green, Blue) pixels.
Question
What's the difference between say, yellow light (575 nm) from sunlight vs. the same…
QEntanglement
- 3,831
9
votes
2 answers
Why does mixing every paint colour produce gray instead of white?
I'm trying to reconcile these facts,
If I had paints of the primary colours and I mixed them together, I would produce gray.
White light contains every colour.
My most convincing attempt to answer the question: The colours of objects that don't…
Hal
- 873
9
votes
4 answers
White light should be black?
If I understand correctly polarisation of electromagnetic wave, two opposite phase wave of same polarisation can cancel each over, so the question is : As white light have all polarisation, all the wave are in equally direction around 360°, and as…
Fabien
- 193
9
votes
5 answers
Is light deflected by external electric and magnetic field?
I recently read about the Maxwell's laws of Electromagnetic Waves and I found that Light is made up of both Electric and magnetic fields.
So now if i pass the light through a capacitor such that the plates are parallel to the light will the light be…
9
votes
4 answers
How can a body be transparent?
How can a body be transparent? I need the theoretical explanation for the same. Has anybody succeeded in doing that practically?
Pranit Bauva
- 653
8
votes
2 answers
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 superposition of light or some other thing?
Shafayet Rahat
- 227
7
votes
2 answers
How does the anti-gravity fountain work?
I just saw this video of an anti-gravity fountain on youtube, but I can't understand how you can reverse the flow of water.
I know you can stop the flow of water by using something called a stroboscope, but how do you reverse it?
ng.newbie
- 179
7
votes
2 answers
What would we see in the sky if it weren't blue
What would we see during the day when we look into the sky (other than clouds), if it weren't for Rayleigh scattering making the sky blue? Would the sky be dark, like at night?
Michael Blake
- 187
6
votes
2 answers
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?
Arseny
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