All Questions
Tagged with classical-mechanics optics
37
questions
-3
votes
1
answer
56
views
Why aren't all objects and their images same in size?
Suppose there is an object in front of a convex lens and we know that the light rays from each point on the surface of object will converge at a different point and form an image. So that means that ...
3
votes
0
answers
46
views
Relating Brachistochrone problem to Fermat's principle of least time [closed]
When I came across the Brachistochrone problem, my teacher said we could relate it to Fermat's principle of least time.
So, we could make many glass slabs of high $\mathrm dx$, and every slab has a ...
- 31
3
votes
1
answer
90
views
Reflection coefficient: Acoustics vs Mechanics
I recently tried to derive the reflection coefficient $R$. This is not a complicated task, however after making some literature research I found two derivations which arrive at seemingly different ...
- 469
0
votes
0
answers
13
views
Simultaneous measurement of the size and mass of nanoparticles in liquid
The size of colloidal nanoparticles in a liquid can be measured from optical reflectance (or absorption) spectra. The smaller the metal (semiconductor) nanoparticle, the more its color shifts to the ...
- 158
5
votes
3
answers
630
views
Is Principle of Least Action a first principle? [closed]
It is on the basis of Principle of Least Action, that Lagrangian mechanics is built upon, and is responsible for light travelling in a straight line.
Is its the classical equivalent of Schrodinger's ...
4
votes
3
answers
292
views
Lossless beam splitter relations
Wikipedia says that for a beam splitter $$\begin{bmatrix}E_{c}\\
E_{d}
\end{bmatrix}=\begin{bmatrix}r_{ac} & t_{bc}\\
t_{ad} & r_{bd}
\end{bmatrix}\begin{bmatrix}E_{a}\\
E_{b}
\end{bmatrix}$$ ...
- 1,038
1
vote
0
answers
94
views
The tilting of solar cells and their efficiency
This is a thought experiment I am considering. It concerns putting solar panels on a flat roof. The question is whether one should tilt them. Whilst there are more mundane reasons for tilting them (eg ...
- 867
-1
votes
2
answers
184
views
How can solve to calculate position of image for any random point and random paraxial rays?
I am a high school student and I have a confusion related to optics {image formation via spherical mirrors) in all my books they say to find location of image its convenient to use the following rays&...
- 470
0
votes
0
answers
56
views
Are there any videos of diffraction grading experiments one photon at a time?
I have seen the video of a double slit one photon at a time but wondering if there is a video of a Diffraction grading experiment one photon at a time.
- 4,083
0
votes
0
answers
40
views
Stroboscopic effect
Can you explain why exactly when I see the rotating blades of a fan or helicopter, there are dark patches and the patches start rotating slowly and even start moving in the reverse direction when seen ...
- 997
2
votes
2
answers
39
views
Is this interference or superimposed image?
When you overlay two identical screens a new patterns forms as they offset. See image:
The two screens are not touching or interacting with each other.
Are the different patterns we see as the two ...
- 4,083
1
vote
1
answer
53
views
Reflection on moving mirrors [closed]
Say I have an endless mirror, in a x y plane, at y=1.
Situation 1: the mirror is stationary and when we send light vertically from the origin, the light reflects back and returns to the origin.
...
- 73
1
vote
0
answers
19
views
Energy flux proportionality
It is considered trivial in texts that if:
$J \propto \frac{\partial \psi}{\partial x} \frac{\partial \psi}{\partial t}$
Where $J$ is the energy flux, then $J$ is proportional to the amplitude of the ...
- 1,038
0
votes
2
answers
63
views
My question is about ray optics particularly image defects
I was learning about spherical abberation and in my book
it is written that when parallel rays pass through lens marginal rays (which are far from principal axis) are bent more than paraxial rays(...
0
votes
1
answer
66
views
Does the minimum slit width change with different photon frequencies?
Send white light through a vertical polarizer and then through a second horizontal gap that is just wide enough to let all the light through. Now slowly close the second gap until it becomes a slit. ...
- 4,083
3
votes
1
answer
238
views
Explaining why rubbing two surfaces together by hand create convex and concave shapes?
From this video (relevant timestamp included in URL):
https://www.youtube.com/watch?time_continue=768&v=ABRysNzcdvw&feature=emb_title
It shows how rubbing two surfaces together by hand with ...
- 799
0
votes
2
answers
47
views
Is the discrepancy in universe expansion in the speed of expansion, the rate that the speed is changing or both?
Is there a simpler way to describe the latest discrepancies or problem with the expansion of the universe. Does the rate of expansion consistently get faster and faster? I was reading this and had ...
- 4,083
1
vote
1
answer
111
views
Is there any meaning behind this $E=mc^2$ "proof"? [closed]
The action $\mathcal{S}$ for a conservative system can be written: $\mathcal{S}=\mathcal{S_o}-Ht$ (because $\frac{\partial \mathcal{S}}{\partial t}=-H$). We also know that: $\frac{\partial \mathcal{S}}...
- 1,168
1
vote
1
answer
175
views
Fermat's principle in classical mechanics?
I do know the principle of least action, but is it possible to formulate classical mechanics based on the principle of least time? That is, if we know the initial state $(x_i,p_i)$ of the particle and ...
- 735
0
votes
2
answers
98
views
Michelson interferometr electromagnetic wave formula [duplicate]
I don't understand why we use this formula:
Instead of this formula:
I mean, why we ignore $\omega\cdot t$ part.
3
votes
2
answers
255
views
How is mass defined by special relativity?
I am eagerly interested in all kinds of areas of physics. As the question of mass has been around for a pretty long time, I am interested about what modern physics namely special relativity says about ...
1
vote
1
answer
982
views
Calculating an "apparent" speed of a beam in a medium
While thinking about relativity, one question sparked my curiosity. If we could observe the trajectory of a light beam by using some partially opaque medium, like smoke, to make it visible, we'd not ...
- 87
14
votes
3
answers
2k
views
Is it possible to apply a torque without a moment arm?
In some statics problems, the question may say something like "a torque is applied about Point B". I've always assumed this was a simplification and the torque was created using a force and a moment ...
- 421
0
votes
1
answer
131
views
Tired Light Frequency Damping
Could voters please give discussion please, please?Thanks
Anyway, I know it’s been discussed but I have not seen good answers as to why Doppler effect is a better idea than the photons frequency ...
- 4,083
0
votes
1
answer
148
views
Do scratches decrease UV protection?
Some scratches have appeared out of nowhere on my new running sunglasses, slightly damaging its mirror coating.
Do scratches on sunglasses decrease its UV protection, or is the UV protection somehow ...
1
vote
0
answers
69
views
Torque on a quarter-wave plate… Where is the force? Where is the moment arm?
If you shine circularly polarized light (carrying angular momentum) through a quarter-wave plate, the light will emerge as linearly polarized light (carrying no angular momentum) from the other side. ...
- 421
1
vote
2
answers
1k
views
$\omega(k)$ and $k(\omega)$ about waves
Wave propagation is characterized by the wavenumber $k$ and the angular frequency $\omega$. Sometimes (like in this answer) the relation $\omega (k)$ is preferred; sometimes instead $k ( \omega)$ is ...
- 767
0
votes
2
answers
108
views
why light differaction occurs on passing small holes?
I have read about the relation between the wavelength and the hole in the Young double slit exiperemnt but I am not sure how that causes diffraction. I only know of one case which is a bundle of light ...
- 161
12
votes
6
answers
8k
views
Light's inverse square law: Does it require a minimum distance from the source?
Does the inverse square law begin to take effect the moment light leaves its source? For example, does light's intensity decrease, i.e. does the area in which the photons might land increase, at a few ...
- 539
18
votes
7
answers
2k
views
When/why does the principle of least action plus boundary conditions not uniquely specify a path?
A few months ago I was telling high school students about Fermat's principle.
You can use it to show that light reflects off a surface at equal angles. To set it up, you put in boundary conditions, ...
- 103k
6
votes
2
answers
1k
views
In geometric optics we treat light as a collection of particles?
I've been reading the book "Geometric Mechancis" by Darryl Holm and the in the first chapter he treats geometric optics. There the author talks about light rays and those light rays looks like ...
- 36.4k
1
vote
0
answers
55
views
Why does not the optical fiber break? [duplicate]
Glass is a very fragile object. So why does not the optical fiber break? Everytime I take them, I am worried about this problem.
- 1,179
1
vote
0
answers
104
views
Explanation of fringe pattern of thin film interference
Recently i went through calculations for finding the path difference between the first 2 reflected rays for a oil film with air on other 2 sides .But i could not understand how the fringes will be ...
- 2,773
0
votes
4
answers
4k
views
Can I use one convex lens to create a telescope?
Is it possible to create a telescope with only one convex lens?
Specifically, is the image I drew below possible?
(This was supposed to be rotated 90 degrees counterclockwise.)
In this picture, the ...
- 768
2
votes
1
answer
1k
views
relation between Schrodinger equation and wave equation [duplicate]
I have always been confused by the relationship between the Schrödinger equation and the wave equation.
$$ i\hbar \frac{\partial \psi}{\partial t} = - \frac{\hbar^2}{2m} \nabla^2+ U \psi \hspace{0....
- 778
11
votes
3
answers
2k
views
Liouville's theorem and gravitationally deflected lightpaths
It is customary in gravitational lensing problems, to project both the background source and the deflecting mass (e.g. a background quasar, and a foreground galaxy acting as a lens) in a plane.
Then, ...
- 3,755
3
votes
1
answer
924
views
Origins of the principle of least time in classical mechanics
Is it possible to derive the principle of least time from the principle of least action in lagrangian or hamiltonian mechanics? Or is Fermat's principle more fundamental than the principle of least ...
- 1,352