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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0answers
37 views
Could path integral formulation be applied to path tracing?
Firstly I have a very shallow knowledge of physics and what I'm about to say may not make any sense at all, I'm just wondering if this could be applied.
The wiki on path integral formulation states:
...
7
votes
2answers
100 views
Why do stars flicker?
Why do stars flicker and planets don't? At least this is what I've read online and seen on the night sky. I've heard that it has to do something with the fact that stars emit light and planets reflect ...
2
votes
2answers
72 views
Why can't some light ever reach earth? [duplicate]
Note: I'm a layman in physics. Excuse me if this question is a duplicate, I lack the knowledge in technical terms to find the answer to this by research (I've tried).
Let's suppose there's a star ...
1
vote
1answer
52 views
Is light particle of wave?
We know that Young's double slit experiment shows that light is a wave.
On the other hand photoelectric effect shows that light is made up of photons.
How can light be both at the same time?
-5
votes
2answers
93 views
Does shadow have mass?
I know it sounds like a foolish question but I have a reason for asking and I'm hoping someone here, can give a convincing response.
Here is why I pose the question...it seems to me that all this ...
3
votes
2answers
103 views
Why does the Sun feel hotter through a window?
I have this big window in my room that the Sun shines through every morning. When I wake up I usually notice that the Sunlight coming through my window feels hot. Much hotter than it normally does ...
1
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0answers
28 views
How close do two wavelengths of light need to be to produce a metamer?
Suppose I have two wavelengths of light ($r_1$, $r_2$) coming from a source. These rays are then reflected specularly on a surface. What is the minimum distance required for the two wave trains of ...
2
votes
0answers
28 views
What is the largest diameter an optical fiber can have? - for nonimaging visible light transmission
Is there any theoretical limitation on the size of the diameter of an Plastic optical fiber? I would like to transmit visible sunlight through it. I see bundles of small cores available but wouldn't ...
0
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2answers
49 views
Is it possible see an invisible light with something similar to a normal lens of an eyeglass? [closed]
Let's say that I am a spy in a room with a lot of people and I want to communicate with my friend using Morse code via a light signal.
Does there exist a type of light (laser or otherwise) that is ...
21
votes
5answers
1k views
Is a proton collision (collisions like in the LHC) visible to the human eye?
I was curious if a proton collision is visible to the human eye.
(This might sound like a really basic question and forgive me if it is. I am very inexperienced in Physics and just wanted an answer ...
-8
votes
0answers
45 views
Is there a regular glasses that I can see invisible light? [closed]
I'm researching a technology: an invisible light that can be seen by a modified standard glasses.
I can not use a pair of glass that looks like a sunglasses.
Did it exist? Any idea?
5
votes
1answer
88 views
What exactly heats a pool of water on a sunny day
On a sunny day an outdoor swimming pool will heat up fairly quickly. My question is, what is the exact mechanism for this and can we put numerical figures on it?
Given that water is clear and ...
1
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1answer
50 views
Is light brightness subjective or can it be quantified?
When we say something is 'bright', is that a subjective interpretation, or does it have a mathematical counterpart, such as intensity?
-8
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5answers
163 views
Is velocity of light constant? [duplicate]
There is a difference between the concept of the speed of light and the velocity of light.
are both of them constant ($dc=0$ and $dv_c=0$)? if yes, why?
17
votes
2answers
922 views
Why myopic people see this picture differently?
I found the following picture in the Internet and I am curious how from a physicist point of view to explain it.
Basically the idea is the following. If you are a normal person - you suppose to see ...
6
votes
1answer
94 views
Distribution of star colours in a galaxy
I'm trying to randomly generate a representation of a galaxy.
I have some Idea on the spatial distribution of stars within a galaxy, and I can find plenty of material on the colour of stars, but ...
-1
votes
2answers
46 views
Light produced from oscillation [closed]
I'm reading Freymann lectures on physics and here's an abstract:
The electromagnetic field can carry waves; some of these waves are lights, others are used in radio broadcasts, but the general ...
2
votes
1answer
53 views
What is the sun's spectral series?
My physics book says that six colors can be distinctly seen in white light: red, orange, yellow, green, blue, and violet. Does solar light only use these six wavelengths and mix them additively, or ...
1
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1answer
62 views
Factors affecting the size of a shadow
What factors affects the size of a shadow and how would you derive the diameter of a shadow of a circular object on a flat screen?
-4
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1answer
67 views
Is it possible to make a light beam act like a stream of water from a spining hose? [closed]
If we had the ability to make an actuator that could turn around at or past the speed of light and I attached a high miliwatt laser to it, then spun the laser around on the actuator at the speed of ...
0
votes
0answers
49 views
How do you estimate colour temperature based on the position of the sun in the sky?
I'd like to estimate the colour-temperature of sunlight (as applied in photography) based on the position of the sun in the sky for a mobile phone app I'm working on (app link from a more appropriate ...
0
votes
1answer
45 views
With a box that has perfect mirrors on the inside would it be possible to trap light? [duplicate]
With a box that has many perfect relective mirrors, would it be possible to trap a beam of light in the box indefinetly?
4
votes
1answer
245 views
Why is light produced when an underwater bubble is collapsed with a sound wave?
Why is light produced when an underwater bubble is collapsed with a sound wave?
I have come across this fact on a page (similar to this) but can't understand "Why". I'm just curious about this ...
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0answers
32 views
Any replies would be really appreciated! Please help me? [duplicate]
Help, please!! Is this an example of Diffraction or Refraction, and why? Thanks! Ps its the triangular block near the bottom of the link page
http://www.suntrek.org/factary/r.shtml
Thankyou so ...
2
votes
1answer
83 views
If time stops at the speed of light is a photon 'everywhere' at once? [duplicate]
I am not a physicist so excuse my question if it's paticularly stupid. As a particle gets closer to the speed of light time slows down as for that particle as compared to a reference from the ...
5
votes
2answers
99 views
Layered CMOS structure question
I am trying to understand the workings of a CMOS image sensor. I understand that increasing wavelength results in an increased penetration depth in the silicon often used in CMOS image sensors. What ...
1
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0answers
51 views
Salisbury Screens and Energy Conservation
From Wikipedia on how a Salisbury Screen works:
1. When the radar wave strikes the front surface of the dielectric, it is split into two waves.
2. One wave is reflected from the glossy ...
0
votes
0answers
28 views
Color of sky scattering by sky dust [duplicate]
Why does we see sky like blue in maximum time?
We know violet has less wavelength, so we should see sky like violet.
My assumption is that, violet is not primary color and not sufficient in the ...
0
votes
0answers
21 views
Specular intensity [closed]
Im currently studying for an exam and have been going through some past papers on the subject, however i have come across a question that has recursively come up each year and the notes on it are not ...
0
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0answers
39 views
Historical aspect of wave theory of light
Huygens thought light as a wave. Wave is a propagation of physical disturbance. We now know that light is electromagnetic field. Electric and magnetic field fluctuates here. What Huygens really ...
0
votes
1answer
66 views
How does gravity effects both time and light if they have no mass [duplicate]
I've been reading about how black holes can effect both time and light with gravity. So I was wondering, doesn't something have to have mass to be effected by gravity? And if so, does this mean both ...
2
votes
1answer
60 views
Is there a one-to-one relationship between colour theories and our trichromatic vision?
This has started to bug me more and more… it involves:
colour theory
the trichromatic properties of our eyes through cone cells
and light.
Is there a one-to-one relationship between colour ...
5
votes
2answers
94 views
If light rays obey to the wave equation, why can they be thought as straight lines?
I'm a newbie with physics but I'm wondering how a ray of light can essentially be represented. I have always known that a ray of light proceeds in a straight line until it encounters another object ...
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2answers
67 views
Refraction of light and frequency dependence
Why do higher frequency waves refract more, both ocean waves and light waves? Also why is energy stored in the frequency as opposed to the wavelength.
2
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2answers
33 views
Penetration of light in the atmosphere
While I was considering an answer to this question, I wondered how much light that enters the atmosphere reaches the ground without colliding with air molecules—if any. I've taken a good bit of ...
30
votes
5answers
4k views
Why doesn't light kill me?
I was attending my philosophy class and in the middle of student presentations, I found myself mentally wondering off and thinking about light. After a few minutes of trying to piece together how the ...
2
votes
1answer
65 views
Optical depth in astrophysics
How can be the exponential decay of the intensity $I$ via the optical depth $\tau$ be derived?
$$I(\tau)=I(0)e^{-\tau} $$
1
vote
1answer
39 views
Relationship between photon polarization and photon angular momentum
What direction is the angular momentum of right hand polarized light points to? Is it vertical to its propagating direction? I want to recognize this in quantum theory.
1
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1answer
56 views
How large of a solar sail would be needed to travel to mars in under a year?
I'm attempting to approach this using the identity
$$F/A = I/c$$
I can solve for Area easily enough
$$A = F(c/I)$$
and I know the distance $d$ is
$$d=1/2(at^2)$$
But I'm having difficulty trying to ...
2
votes
1answer
37 views
Relation of color and frequency for the visible spectrum
In this question the OP is looking for a way to see light that is outside of the visible spectrum without using electronic sensors. This got me wondering about the visible spectrum itself. Typically ...
0
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1answer
53 views
Is there a way to see light frequencies invisible to the human eye without the use of electronic sensors?
I wonder if it's possible to be able to see light frequencies that cannot be normally seen by human eye, without using sensors designed specifically for detecting a certain spectrum range, but rather ...
3
votes
2answers
83 views
Is light's path a wave?
In a lot of textbooks I see a schematic of light drawn as a squiggly line. I have even heard that some things are too small to be seen because they are smaller than the wavelength of light (and ...
0
votes
1answer
42 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?
1
vote
1answer
135 views
Why does Lorentz factor not hold for relativistic mass when we apply it to photons? [duplicate]
We know that the photon itself is massless particle $m_0=0$. But we also know, that the mass of the objects does increase with their energy. And we know that under certain circumstances (gravity, ...
0
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2answers
172 views
Does more reflective aluminum foil make a room cooler compared to less reflective foil?
Aluminum foil is said to be not absorbing light at all.
It reflects light. So, does it mean that a more shiny aluminum foil will reflect more light and thus make the room more cooler as compared to ...
0
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2answers
39 views
Paraxial rays and marginal rays question
Paraxial rays are found to focus far away the lens whereas marginal rays focus near to the lens, why? I didn't find satisfactory answer in my academic book..
1
vote
1answer
95 views
Could the shadow move with faster-than-light speed? [duplicate]
If I make a huge laser with a figure for shadow in front of the laser, and I shine it on to the moon, will I see the light from the laser AND the shadow moving the same speed? (I read somewhere the ...
0
votes
0answers
18 views
Minimum thickness of bubble ensuring max reflectance
A soap bubble has index of refraction of 1.33. What minimum thickness of this bubble will ensure max reflectance of normally incident 530 nm light?
Ans is 99.6, but how do I get that?
I am ...
1
vote
2answers
100 views
Keep the light beam in a closed room, is it possible? [duplicate]
I mean if I am in a room totally closed to light. If I switch on a torch for a second then switch it off. So will the inside of room be always bright?
1
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2answers
58 views
How does one subtract two light beams?
From what I understand, it seems like you can only "add" beams together. You can use a beam combiner, basically using a beam splitter in reverse, to combine two beams. In homodyne detection, you use a ...
