All Questions
5,196 questions
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Exactly which objects should we considered as colorless? [duplicate]
My question is which objects are considered as colorless?
In chemistry we sometimes consider white object as colorless,Many times we use the word colorless for transparent substances like water, glass,...
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0
votes
2
answers
108
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Is the nature of light determined? [duplicate]
Is it determined that light is a wave or a particle or it still exists as a dual nature?
because young's experiment said that light is a wave but still I hear people saying that light shows both wave ...
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1
vote
1
answer
67
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How does the mirror clock work in an accelerating spacecraft?
I recall Feynman explaining time dilation in a moving spacecraft using a clock which counts reflecting light. As I understand it, to a stationary observer the path the light takes is longer than it is ...
- 2,288
-2
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1
answer
37
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Struggling with interference [duplicate]
I was reading the book optics by zajac and hecht. It was a nice one until physics optics, i got that interference becomes when the light is coherent and monochromatic, and it is the superposition of ...
2
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3
answers
394
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How could RGB color system compose a violet color?
In the GRB system, we combine the three primary colors, red, green, and blue, to make some new colors.
It's easy to understand the production of yellow because the wavelength of yellow is between red ...
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3
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1
answer
172
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Infinite reflection inside a glass loop
If you had a loop made of completely transparent glass (or other material), in the shape of a donut; think atomic collider (but probably not needing to be so large :) ), and you introduced light from ...
4
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1
answer
110
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Absorption respose of cones in eye
I am trying to find information about the absorption response of the cones in the eye to different wavelengths of light. I have noticed two types of graphs and answers: one which shows the S-...
- 2,740
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1
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76
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Let's say I have manufactured a prism from a non-dispersive medium, then light coming from air wouldn't split into colours right?
Let's say I have manufactured a prism from a non-dispersive medium, then light coming from air incident on the prism wouldn't split into colours, right? I mean light still changes direction, but all ...
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1
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136
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Why is deep open ocean blue?
If we assume the ocean is sufficiently deep so that the blue light transmitted inside the water gets absorbed completely before it reaches the ocean floor and be scattered back towards the surface, ...
2
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1
answer
132
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What is the speed of light in case of Critical Angle?
When light travels from an optically denser to a rarer medium, it bends away from the normal and at a specific angle of incidence, the angle of refraction is ${90}^{\circ}$. When the angle of ...
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2
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65
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Which factors determines whether a photon is absorbed? [duplicate]
After some research, I figured out that all EM waves/photons are absorbed by atoms by exciting an electron from an orbital to an other. However, atoms emit only certain EM waves with specific ...
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1
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91
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Why does there need to be a particle representation of light?
Why does there need to be a particle representation of light? Doesn't light as a wave explained the observations of the photoelectric perfectly? When the frequency of light is increased, the speed of ...
5
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3
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282
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Connection between photons and EM waves
We learn about electric and magnetic fields and how they conform EM waves. Then we discover the photon and how there was a duality between this two ideas, sometimes radiation behaved like a wave and ...
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1
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0
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49
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Are there any nonlinear crystals or other transparent materials that can produce anti-Stokes, phase matched, frequency shift of laser light?
While some nonlinear crystals can convert incoming laser light into harmonics, thus for example doubling the light frequency, are there any crystals or other transparent materials that can reduce the ...
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0
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73
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Schlick's approximation for reflectance when $n_1 = n_2$
another raytracer here.
I'm using Schlick's approximation to the Fresnel equations, which is said to be reasonably faithful.
I'm a little puzzled about the situation where the incident ray is just ...
- 101
6
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3
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2k
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What property of light allows it to propagate in space? [closed]
I got this question in a university entrance exam; I'm not sure what could've been the answer. I've scoured the web and could hardly find a decent answer. The question and choices were:
What property ...
8
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1
answer
522
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Skylight reflection shows birefringence patterns
I noticed that the skylight where I work looked white to me, but its reflection from the tiles below showed a colorful pattern. See the images below, and also a video that shows this effect from ...
- 12.6k
2
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1
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63
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Confusion about EM absorption [duplicate]
I have now encountered various explanations on how matter interacts with electromagnetic waves (EM) but it still seems like an unconnected mess. The best way I can demonstrate my questions is with an ...
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0
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37
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Why are the hottest stars appear mostly in blue or blue-white? [duplicate]
Does it have to do with anything regarding wavelengths and frequencies..
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0
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0
answers
18
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What is a simple way to estimate $σ_{RV}$ assuming photon noise in radial velocity measurements?
Hello there i have been trying to figure out what is wanted in the question "Simple way to estimate σ_RV assuming photon noise" for a presentation. But i can not seems to find much, but i ...
0
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1
answer
200
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Phase change in a wave travelling through different media
Suppose I have a wave, and two mediums with different indices of refraction. When the waves pass through these two mediums, will there be a phase change between the waves that comes out from the first ...
0
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3
answers
294
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How does light not have mass? [duplicate]
How is it possible for light to have zero mass because it was my understanding that in order for "stuff" to exist it has to have some form of mass? And if it does not have mass then can it ...
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1
answer
67
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Can an atom according to Bohr's model be considered a black body?
I recently read about Bohr's atomic model and found out that an atom tends to absorb all the energy of a particular frequency to excite its electron and it also gives the same amount of energy that it ...
3
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0
answers
69
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Why is sunset in mars blue?
This is the Martian sunset, as captured by the Spirit rover of NASA. Notice the colors are inverted, i.e. the direct rays blue and diffused rays red, which is exactly the opposite of what you would ...
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-2
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1
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89
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Why does sound travel in a wave? [closed]
Sound waves carry energy. Why does sound travel in a wave instead of a straight line when travelling in a wave covers more distance and is less energy-efficient than travelling in a straight line? ...
0
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0
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34
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Is there really a relation between light intensity and color saturation?
Going through this article on Wikipedia, under the saturation section, I came across "The purest (most saturated) color is achieved by using just one wavelength at a high intensity, such as in ...
- 1,106
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1
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108
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How to explain interference pattern in our eye?
Suppose we got a Lamp L that emits some light. The light afterwards hits a diffraction Grating G at a distance a. Now if you were to look through the grating with your Eye E, you were to see the ...
- 471
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47
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What will happen to the light due to frame-dragging?
Imagine a rotating black hole is blocking a cluster of stars that I'm observing. Thanks to gravitational lensing I could still see the stars albeit shifted away from their original locations. So now ...
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18
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Does anyone know the correct way to verify the color temperature of a given light source in a color booth and the equipment needed?
ie. spectroradiometer on the floor (constant distance) of the booth directly measuring the "observed" color temp emitted directly from the light source? is it more acurate to measure the ...
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2
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81
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Amateur Shower Thought Question About Time and Space
Apologize in advance if this is the wrong group. I often watch Netflix shows about blackholes explained in a nutshell or laymen’s terms.
I had a recent thought/scenario that may relate to some ...
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1
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124
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Lambertian surface and the luminous intensity
I am currently studying the basics of photometry to better understand the rendering equation of Kajiya. One thing I'm currently struggling with is Lambert's cosine law.
Let's go over the premises:
A ...
6
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2
answers
2k
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Wavelength of "complementary colours"?
In physics/chemistry/the life sciences there's a common experimental method of determining the concentration of a sample using spectrophotometers. We can measure the absorbance of the sample at a ...
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2
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191
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Do the interference of two EM waves with the same frequency but different phase cause the EM waves to slow down?
So this question is inspired by the explanation of EM waves slowing down in a material through interference with waves produced by the material in response to the incoming EM wave. You can see ...
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1
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2
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105
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Conflicting lensmaker's equation representation
I keep finding these two conflicting forms of the lensmaker's equation. I understand that (n2-n1)/n1 is the same as (n-1) if referring to a lens in air, but I can not make sense of why the reciprical ...
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1
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41
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What happens to a photon leaving a grav well if it doesn't have the energy to get out of the well and the object it's leaving isn't a black hole?
Light exists with energy E = hf. That is supposed to be quantized and discrete but maybe "f" in the equation is continuous when not emitted specifically from an electron (moving through the ...
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2
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1
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112
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Does the probability wave of a photon determine its color?
The wavelength or frequency of light determines its color. Photons seen as particles are said to have a frequency, determined by its energy, so I assume that 'is' the same color.
But being quantum ...
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3
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1
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70
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Can a system of lenses or compound lens have a higher numerical aperture than a single element in the system?
I am attempting to create a simple Abbe condenser for a microscope, which typically consists of two converging lenses.
Ideally, I would like to achieve a numerical aperture for the condenser of ...
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1
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2
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45
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Do there exist materials whose Opacity varies with temperature?
Do there exist materials whose Opacity varies with temperature?
E.g a Material that becomes more Opaque as it gets hotter?
- 3,001
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56
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Is the Fourier Transform a reliable way to infer the physical phenomena producing an RF signal?
Consider the following thought experiments:
Scenario 1:
A person standing far away shines 3 light beams at you, each beam having a narrow spectral distribution centered around different frequencies F1,...
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1
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57
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Can I recover the physical wavelengths present in a light source from a time-series measurement of its amplitude?
Consider a mixture of different wavelengths being emitted from the same point (ex: a star). This light consists of a mixture of wavelengths and intensities at each wavelength. When measuring the ...
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3
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2
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988
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Would the "FFT" of a light source be a reliable indicator of perceived color?
Paraphrasing from here:
A purely monochromatic 575nm wavelength light would be "perceived" as yellow, as would a light that has equal components in red and green (but no yellow). However, ...
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1
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1
answer
127
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450nm peak absorption [closed]
I am looking for an oxide compound (metal oxide, or similar preferably inorganic) which shows light peak absorption at 450 nm. I have troubles in finding the right compound, as most of the oxides have ...
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23
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1
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7k
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Based on my calculations, we cannot see the Earth from the ISS. Obviously it's wrong. Why?
What started as a fun exercise really annoys me because I cannot see where I got it wrong.
I initially wanted to see how many photons hit a pixel of a camera on the ISS pointed at the Earth - but I ...
- 1,015
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2
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48
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Is reflected color not from the wavelength corresponding to that color?
I was reading through Josef Albers' interaction of color (a classical art color theory book), where he makes this point:
If I see a substance, or pigment of a particular color, doesn't that mean I'm ...
- 1,106
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0
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95
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Derivation of optical resolution
I'm trying to prove optical resolution formula from scratch and im having a hard time doing it. I dont know much about optics (im studying cosmology) and i need a detailed proof of optical resolution ...
4
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5
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526
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Is the speed of causality slower in water?
I've recently read that what most people learned to think of as the 'speed of light' is actually the 'speed of causality', and that light just happens to travel at that speed (through free-space.) I'...
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1
answer
204
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Number of fog droplets in the air
I have an issue with the official solution to this problem from BelPhO:
Visibility on the road is 100 m. Assuming that the diameter of a fog
droplet is 1 micron, estimate the concentration of fog ...
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2
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0
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57
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Would ocean tides on the moon of a gas giant really be kilometers high?
I was reading an article on exomoon habitability constrained by illumination and tidal heating. The article imagines an Earth-like exomoon around Jupiter-like host planet. That got me thinking about ...
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6
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2
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572
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How smooth must a surface be to produce specular reflection, and do Lunar boot prints meet this standard?
Question: How smooth must a surface be to produce specular reflection, and do Lunar boot prints meet this standard?
A recent post on Space Exploration asked why footprints on the moon displayed ...
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2
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106
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Does Law of Reflection gets violated?
I was curious as to why the "Law of Reflection" is only a law and not a principle. Are there any specific conditions or circumstances where it is not followed by chance? If so, how so?
Note: ...
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