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Questions tagged [waves]

Waves are disturbances that propagate through space and time. Classically, they travelled through a medium, disturbing the particles but not changing their mean position. Electromagnetic waves/particle-waves need no medium; they are disturbances in their respective fields.

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What is the frequency of a standing wave? [closed]

I understand that constructive interference of waves results in standing waves. And for a wire with both ends fixed the frequency should match the fundamental frequency of the wire to produce standing ...
android's user avatar
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Is there an IR-camera-detectible color that can be the coat for a material to transfer the material heat by emitting into the space? [closed]

If we see a material it is coloured in a color that our brain could easly recognize. But when we look at it by the help of an IR camera it could also be coloured and if two materials have same ...
Emilija Bradvica's user avatar
4 votes
3 answers
224 views

Galilean invariance of the wave equation

Given the wave equation for a material wave: $$\frac{\partial^2 \phi}{\partial x^2} = \frac{1}{c^2} \frac{\partial^2 \phi}{\partial t^2},$$ we can apply the Galilean transformation $x'=x-Vt$ and $t'= ...
Hubert van Luytelaar's user avatar
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2 answers
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Why the frequency component is not included when the energy of a wave is described?

Energy of a wave is directly proportional to its Amplitude squared. There is no inclusion of frequency in it. But by intuition if one thinks about it, isn't it obvious that a wave with higher ...
Vibhav shivadeker's user avatar
1 vote
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24 views

Connection between dispersion relation and symmetries of the Hamiltonian

I am having trouble understanding intuitively the connection between the dispersion relation and the symmetries of the Hamiltonian. For example, suppose we have a lattice and there are four sub-...
JosephSanders's user avatar
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1 answer
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What is the mathematical support for the formula $f_n = n f_1$, used to calculate the frequency of a standing wave? [closed]

could someone explain to me the mathematical support for the formula $f_n = n f_1$. This formula refers to the fact that the frequency of a standing wave is equal to the number of antinodes times the ...
Santiago Celis's user avatar
36 votes
5 answers
5k views

Why does the pet's water bowl overflow?

So when i give the pet fresh water in a stainless steel bowl that i place on a mat according to the attached picture, from $t=0$ the bowl is at rest, the water normally oscillates in the bowl like a ...
user721108's user avatar
-1 votes
0 answers
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Doppler effect for multiple sources [closed]

Given the figure below, how can I determine the speed from the two sources given that they both produce a frequency of 1000 Hz, and the speed of sound can be assumed to 340 m/s. The sources are both ...
Alex123's user avatar
0 votes
2 answers
123 views

Diffraction when the wavefront is not parallel to the plane

I am studying Feynman's chapter on the origin of the index of the refractive index (see this link). If I am not mistaken, what he does is to prove that when a wave enters a medium (modelled as a ...
Plop's user avatar
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2 votes
2 answers
75 views

The "small amplitude" assumption in the derivation of the wave equation for the string

I am reading about the wave equation for transverse waves in a string from the book Mathematics of wave propagation (2000) by J. Davis. On page 10, just before the derivation of the (one-dimensional) ...
DinoS's user avatar
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1 answer
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Directionality of EM Waves in Double Slit Experiment

In the experiment of any wave through the double slit we see and model the interference pattern as shown. In this depiction that means the wave propagates in/out of the page. ie we are seeing a sin ...
cav3's user avatar
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Phase Slope Distance Calcuation

After trying to implement IFFT algorithms for phase-based ranging, as outlined in this very interesting and descriptive blog post; I've been getting horrendous results (orders of magnitude inaccurate),...
Hysan Happy's user avatar
1 vote
0 answers
27 views

What actually happens when light goes into a waveguide?

I have only dealt with a rudimentary theoretical treatment of how light propagates inside a waveguide, such as those available in Griffiths. One thing bugging me is that I still do not know how ...
hendlim's user avatar
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1 vote
0 answers
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Wave interference and fluid dynamics question

I'm curious to find an answer to this question: In the college canteen I would often slide my Styrofoam cup of milky coffee across the melamine table top. (unlike paper or plastic, Styrofoam is a ...
questing-monkey's user avatar
2 votes
0 answers
38 views

Direction of propagation of extraordinary wave inside a birefringent medium

I am reading Optics by Ajoy Ghatak, in which the author explains the phenomenon of double refraction in a calcite crystal using Huygens' principle. My query is in the analysis of the case of normal ...
Enigma's user avatar
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1 vote
2 answers
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Human error in wave experiment

I am trying to see what the fundamental frequency of a string is by slowly increasing the frequency on a function generator. This experiment relies on the experimenter to record the frequency as soon ...
risa's user avatar
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1 answer
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Why does radiation of small wavelength interact with small objects?

I was reading chapter 2 from the book 'Diagnostic Radiology Physics : A handbook for Students and Teachers', and came across the following quote "X rays of energy of a few tens of ...
In the blind's user avatar
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How to compute the diffraction efficiency of a thin phase grating with arbitrary groove shape?

From Magnusson and Gaylord (1978), the wave amplitudes, $S_i(z)$, of $p$-polarized light for a thin, arbitrary phase grating are given by the equation $$ \frac{\partial S_i}{\partial z} + \gamma \sum_{...
Roy Smart's user avatar
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5 votes
2 answers
231 views

Huygens' principle and the laws of reflection/refraction

As I understand the Huygens principle, all points on the wavefront are sources of secondary spherical wavelets and the tangent to these wavelets will form new wavefront. This is used to prove the ...
Yevgeniy P's user avatar
0 votes
1 answer
40 views

Understanding Loop Formation in a Plucked String

I have a question regarding the formation of loops when a string is plucked at different fractional lengths. In a book I referenced, it is stated that plucking a string at 1/6 of its length produces 3 ...
Engr Fahad Safi's user avatar
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2 answers
151 views

Weird looking sine wave behavior in an electric circuit

while studying an RLC circuit I noticed some weird like sine waves at low frequencies (1-9 kHertz) on the inductor, The amplitude behavior did not follow the theoretical model. Instead, suggested the ...
dareen's user avatar
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-1 votes
2 answers
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Where did the energy created go if there are no non conservative forces like friction acting in my scenario?

In my scenario, there is a string (which is elastic and massless) which is tied tightly to a wall and other end is fixed to a machine which can create waves without human error. If half wave with ...
Jyothi Srivalli's user avatar
3 votes
1 answer
58 views

Decoupling Linearly Coupled Wave Equations with Potentials

I'm currently working numerically with wave equations and I was wondering if one can always decouple two wave equations, with potentials, which are linearly coupled. The system I'm talking about is ...
Afraxad's user avatar
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-4 votes
0 answers
33 views

What if The Wave in the double slit experiment is measured but one full wave and the other waves 1/2 of it and the other 1/2 is not observed? [duplicate]

What will be the result either nothing it breaks or does it give any answer. double slit experiment with two slits what would happen if we add the angles for slit and angle for detectors and also the ...
Ammar Hafeez's user avatar
0 votes
2 answers
75 views

Is it possible for a double slit experiment to create an interference pattern at 90 degrees?

If the light diffracts perpendicular to the slits, then would an interference pattern 90 degrees from the slits be observed?
adklasjld's user avatar
1 vote
0 answers
39 views

Intensity of light - questions about the particle standard definition and concerning the units [duplicate]

In the $5.111$ MIT class, lecture $3$, it is written on the last slide "intensity of light = photons per second". Intensity is previously defined in the lecture as the square of the ...
niobium's user avatar
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0 votes
1 answer
117 views

Why is the Poynting flux not conserved across the interface between two conducting materials?

This question is part of my attempt to use an answer to another question I've posted on this site. If I have two materials with complex indices of refraction, $\widetilde{n}_0$ and $\widetilde{n}_1$, ...
Roy Smart's user avatar
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0 votes
1 answer
40 views

What's the phase of different points in a standing wave?

The equation my book gives for a standing wave's disposition from it's equallibrium is: $$\displaystyle y=2A\cos \left( \frac{2\pi x}{\lambda}\right) \sin \left( \frac{2\pi t}{T}\right)$$ Where the ...
Nick The Greek's user avatar
0 votes
1 answer
31 views

${}$Doppler shift

If observer is moving and source is at rest then i can treat the scenario with approach in which observer is at rest and source is moving since this is what will be happening according to the observer ...
Muzzammil Ahmed's user avatar
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0 answers
22 views

What is a Freely vibrating stationary wave?

My textbook says "Stationary waves that vibrate freely...." What does vibrate freely mean here? Does it mean a stationary wave that vibrates in a vacuum?
S Paul's user avatar
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2 votes
1 answer
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Is there a way to use the optical transfer-matrix method to determine the absorbance of each layer in a multilayer stack?

I've implemented the transfer-matrix method to determine the the transmittance and reflectance of a multilayer stack of thin films. I know that (ignoring scattering) the absorbance of the entire stack ...
Roy Smart's user avatar
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3 votes
0 answers
47 views

Stationary waves do not transfer energy [duplicate]

My A-level physics textbook states: "Stationary waves that vibrate freely do not transfer energy to their surroundings". I do not understand this statement. How can it not transfer energy to ...
S Paul's user avatar
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0 votes
0 answers
43 views

Spherical laser beam terminology

I am currently seeking the correct terminology for a beam that expands linearly from a fixed point, resulting in its wavefronts forming spherical surfaces. However, the beam does not expand in all ...
mathslover's user avatar
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0 answers
42 views

Mathematical definition of a wave [duplicate]

I am aware that, in general, a wave is a type of energy transfer (though I admit I don't know if there are more complicated types of waves for which this isn't true). But I want to understand how a ...
user35013's user avatar
5 votes
3 answers
2k views

Is it possible to get an electromagnetic wave equation if the speed of light were infinite?

In an old question: How would night sky look like if the speed of light was infinite? the best answer was voted down to negative credits. I cannot understand why. From Maxwell's equations, we derive ...
wiljo's user avatar
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1 vote
1 answer
87 views

What is light? how is it connected to electromagnetic radiation?

I am trying to understand how light works and electromagnetic radiation, from what I understand charges cause disturbances in electric fields, which triggers a magnetic field, and then the back and ...
Ranvir Choudhary's user avatar
0 votes
0 answers
38 views

Cross section along the single transmission path of electron

I am studying this research paper "Forecasting of ionospheric vertical total electron content (TEC) using LSTM networks" about ionosphere, but in introduction section I phrase I didn't ...
D. S.'s user avatar
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0 votes
1 answer
62 views

Doubt regarding time lag during photoelectric effect

Recently,I was reading about the photoelectric effect and have a doubt regarding it: Suppose I irradiate a metal surface with a monochromatic beam of light of frequency 'μ' such that μ > μ0 where ...
Ishaan's user avatar
  • 517
0 votes
1 answer
23 views

Amplitude based on number of equal sources

A homework problem states the following: In a urban road with a lot of traffic the sound level produced by a flow of a 100 cars per minute during the day is $B_1 = 80$ dB. Calculate the sound level $...
NICOLA TROMBINI's user avatar
0 votes
0 answers
32 views

Electromagnetic Field in a 3D Cavity with Lossy Boundary

I would like to find the electric and magnetic fields inside a cubic cavity with a lossy boundary (i.e. NOT a perfect conductor). I assume that the interior of the cavity is filled with a homogeneous ...
amrit 's user avatar
-2 votes
1 answer
57 views

Generalised wave equation from Maxwell's equations [closed]

I was playing around with Maxwell's equations and I've found a linear combination of the electric and magnetic fields which also satisfies a wave equation, but I don't know the implications of this. I ...
Lagrangiano's user avatar
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1 vote
1 answer
28 views

Resonating string with increasing amplitude

The situation goes like this: We have a tuning fork at one end of a string (whose other end is fixed to a wall and length $L$). The fork is vibrating with small amplitude so we approximate this end of ...
Athulkrishna.S's user avatar
2 votes
2 answers
55 views

Why is a monochromatic wave temporally coherent for all time delays $\tau$?

I've been learning about coherence of waves and the Wikipedia page on says a monochromatic electromagnetic plane wave is coherent because: A wave containing only a single frequency (monochromatic) is ...
Hadi Khan's user avatar
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2 votes
2 answers
554 views

Burgers' equations and shock waves

Given Burgers' equation, $m_{\tau} + mm_x = 0,$ one expects to have discontinuities and thus shock waves in the case the initial conditions are smooth. For example, one may take $m_0(x) = \sin(x), x\...
user996159's user avatar
3 votes
0 answers
80 views

Why does the wavelength of gravitational waves increase with larger energy?

Gravitational and electromagnetic waves are quite similar, as both are fundamental force waves that travel at the speed of light and have no limit to their range, but when it comes to electromagnetism,...
Quantum Wonder's user avatar
1 vote
0 answers
16 views

Why is the intensity of a beam of light the squared magnitude of the phasor and not just the squared magnitude of the real part?

I'm learning about phasors and light intensity and there are two conflicting things I've been told that I can't reconcile. Firstly I've been told that a phasor $e^{-ikz+i\phi}$ is a mathematical way ...
Hadi Khan's user avatar
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1 vote
0 answers
28 views

How does parameters of the constitutive relation of electromagnetic media be constrained as for chiral, nonreciprocal or loss media?

The constitutive equations are: $$ \bf D =\varepsilon E +\xi H \\ B =\mu H + \zeta E $$ Why, when the media is nonreciprocal, the parameters $\xi$ and $\zeta$ only can take the real part equals zero,...
Hing Cu's user avatar
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0 votes
1 answer
46 views

How does flute work?

I started learning flute a few months ago. Here in India you can buy two types of flute hindustani and carnatic. Hindustani flute has a simple acoustics. Lenth is inversely proportional to frequency. ...
Newtron Malayalam's user avatar
1 vote
1 answer
117 views

How is the wave equation derived or discovered? [duplicate]

I don't really understand where the fundamental or general wave equation $$\frac{\partial^2y}{\partial t^2} = v^2\frac{\partial^2y}{\partial x^2}$$ comes from. I understood the derivation of wave ...
Jack's user avatar
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1 vote
1 answer
51 views

Would we be able to see the superposition of two X-rays where the frequency of the modulation matches visible light?

Suppose I had the superposition of two electromagnetic waves whose angular frequency was in the X-ray region. Together they form a composite made of a carrier wave and a modulation wave where the ...
Hadi Khan's user avatar
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