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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Double slit - higher dimensions
The double slit experiment is a real-life manifestation of the Huygens principle. As is well-known, this principle depends on whether the number of dimensions is ever or odd; as Evans1 puts it,
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Pressure underneath wave
I enjoy water sports and activities in the water. I've swam around and dived down enough to need to equalize my ears and in general have felt water pressure.
I've since taken up surfing and have ...
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Can a "depressive soliton" wave exist? That is, can we have a trough without any crest? Why or why not?
I know that "soliton" waves can consist of a crest without a trough. One would expect the reverse to be true as well.
However, this Wikipedia excerpt says,
So for this nonlinear gravity ...
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Relation between the electric and magnetic fields for an arbitrary electromagnetic wave
When solving the wave equation for electromagnetic waves,
$$
\nabla^{2} \mathbf{E}=\mu_{0} \varepsilon_{0} \frac{\partial^{2} \mathbf{E}}{\partial t^{2}}, \quad \nabla^{2} \mathbf{B}=\mu_{0} \...
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Can ray-tracing be used to design a stealth air craft? Or is it necessary to use wave theory?
This question is inspired/kicked-off by a question over in Aviation SE asking about the design of stealth air craft.
Stealth technology is usually referred to when trying to make vehicles invisible ...
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Physical intuition for the solutions of the wave equation
I have been studying the wave equation in $\mathbb{R}^n$ for the cases $n=1,2$ and $3$. In the three cases, working all over $\mathbb{R}^n$. That is:
$u_{tt}(x,t)=c^2 \Delta_{x} u(x,t)$ for $x \in \...
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Explaining phase shift from a half-silvered mirror
I am trying to understand why light undergoes a phase shift when reflecting off one side of a half-silvered mirror, but not the other side.
This Wikipedia page and this answer both give the following ...
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Can the Taylor expansion of Energy/Intensity be explained more in-depth?
In reference to the question, "Why is energy in a wave proportional to amplitude?" Ben Crowell answered with the answer attached. The original post is linked here. I did not respond to the ...
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Numerical Solution of the Propagation-Dispersion equation
I have asked this question on Computational Science and also on Mathoverflow, but no satisfactory answers so far. I thought maybe the physics community could shed some insight on the issue.
I am ...
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Does sound need an odd number of spatial dimensions?
In the book "when Einstein walked with Gödel" the author talks about Edwin A. Abotts "Flatland" stating that one problem which was unattended by Abott is the problem of acoustics ...
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On sum of amplitudes in Wave Mechanics
Consider Schroedinger equation, which I write in the form $$ (\mathscr{L}+V)\psi=0$$where $\mathscr{L}$ is the kinetic and time-derivative operator. Now, imagine I have two point sources 1,2 with ...
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Does the two slit experiment fall apart if there is dust in the room?
All the pictures and videos of the two slit experiment show the photons hitting the back screen in the interference pattern. Does this fall apart if there is dust in the air and the photons hit a ...
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Does rope in a standing wave expand and contract as it moves between being straight vs sine?
Images of standing waves often show two people using a jump rope. The shape of the rope goes from straight to waves to straight, then a sine wave the other way and then straight again as it repeats. ...
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How loud is the Perseus cluster?
The gas near the center of the Perseus cluster exhibits quasiperiodic pressure oscillations that can be interpreted as sound. I found a paper that says that these pressure waves have a wavelength of ...
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Sound conduction in a stethoscope
i am trying to build a stethoscope and since i have no idea about physics and acoustics i wanted to ask some questions, hoping Somebody can help me.
I mainly have some questions regarding the tubing ...
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Formulate the equations that describe this transmission-line circuit (Veritasium's circuit)
My question
Consider the following circuit. Two non-resistive long transmission lines ($R' = G' = 0 \text{ } \Omega$) , each of the same length $L$ and same inductance per unit length $L'$ and same ...
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Confusion regarding Young's double slit experiment in different media
The Problem
Consider the given arrangement:
Point $P$ is equidistant from $S_1$ and $S_2$ .The glass slab in air has refractive index $\mu_{2}$, and the one in water($\mu_{1}$) has refractive index $...
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Why is the speed of sound wave in a gas always lesser than the r.m.s. speed at the same temperature?
My book says that the speed of sound wave in a gas is always lesser than the r.m.s. speed of the gas at the same temperature. I understand that speed of sound is given by:
$$v_s=\sqrt{\frac{\gamma RT}{...
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Why do scattered waves vanish when the wavenumber of the incident wave is an eigenvalue of the interior Dirichlet problem. Where has the energy gone?
I normally work with numerical computations for wave scattering, but I am now trying to get a better understanding of the physical processes underlying the theory, in particular, what happens to the ...
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On why in transparent media light speed is altered by elastic scattering of photons and their path lengths
I have read this:
https://en.wikipedia.org/wiki/Higgs_boson
Where it says:
"Symmetry breaking
in optics In a vacuum, the light of all colours (or photons of all wavelengths) travels at the ...
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Why is the total force at a free surface zero?
I am looking into waves on a free surface for which their are two main conditions:
Kinematic condition: Particles on the surface remain on the surface.
Dynamic condition: Forces acting on the surface ...
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Characteristics of wavepackets
I've been learning about wave packets and group velocities recently and had a question. Using simple trigonometric identies, we can show that the super position of two traveling waves with frequency-...
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How to get the pressure amplitude at any spatial point?
Working on the pressure equation from the linearized euler equations, I stumble across a very simple problem :
How, from the pressure solution of the specific equation (see http://www.acs.psu.edu/...
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Polarization of a transverse wave travelling in ionosphere with polarization direction perpendicular to earths magnetic field
Assume a transverse electromagnetic wave entering ionosphere such that its electric field is perpendicular to Earth's magnetic field. Now, I read that as it will enter plasma, the wave will tend to be ...
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Boundary conditions for enthalpy waves inside a pipe
So I'm trying to solve a form of the wave equation for sound produced by a vortex distribution $\vec{\omega}$ convecting at velocity $\vec{v}$ .
$$\left(\frac{1}{c_0^2} \frac{\partial^2}{\partial t^...
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What's the difference between exchange spin wave and magnetostatic spin wave?
So far I've heard of three kinds of spin waves
Magnetostatic spin waves (MSW)
Dipole-exchange spin waves (DESW)
Exchange spin waves (ESW)
What's the difference?
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Is there an explanation for this unexpected similarity between binomial coefficients and waves?
Background
Binomial coefficients appeal mostly in probability, combinatorics number theory etc so we were surprised when we observed something that appeared to belong more to physics than pure ...
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Why does the wavelength of gravitational waves increase with larger energy?
Gravitational and electromagnetic waves are quite similar, as both are fundamental force waves that travel at the speed of light and have no limit to their range, but when it comes to electromagnetism,...
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Why do water surfaces have persistent "average wavelength" patches?
Have you ever stood above a river or lake and noticed that the surface has visible "patches"? It looks like the surface has different average wavelengths in some areas, leading to the light ...
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Can you observe Rayleigh scattering of water waves?
I understand roughly that Rayleigh scattering occurs when white light encounters particles smaller than the wavelength of visible light, and short wavelengths are preferentially scattered.
I'm ...
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Wave equation derivation in a transmission line
$$
V(x, t) = L\Delta x\frac{\partial I}{\partial t}(x, t) + \frac{1}{C \Delta x}\int{I_c(x, t) \; dt} \tag{1}
$$
$$
V(x + \Delta x, t) =\frac{1}{C \Delta x} \int {I_c(x, t) \; dt} \tag{2}
$$
$$
I(x) = ...
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Why the fields of the quasi-TEM mode of microstrip line tend to concentrate in the dielectric as frequency goes higher?
A microstrip line is a waveguiding structure as shown below:
Because of the inhomogeneity, the fundamental mode of propagation is a quasi-TEM mode, which means that the z components of the E and H ...
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Understanding difference between classical and quantum harmonic oscillator probability distributions
Here we have an example QHO wavefunction squared in blue overlayed an equivalent CHO probability distribution. I'm trying to understand intuitively why the QHO result has zeros, i.e. points where we ...
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Shield gamma/X-ray/ultraviolet radiation without blocking radio waves
I was theoretically considering building an airtight enclosure that shielded the insides from gamma/X-ray/ultraviolet radiation but did not block radio waves (so that communication would not be ...
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Relationship between resonance frequency of a cup and amount of water filled
For a science project I chose to investigate the relationship between the resonance frequency of cups and the amount of water filled in it. I filled the cup with 10 grams of water each time, and used ...
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Can a metallic rectangular waveguide support hybrid modes?
Studying the basics of guided waves in metallic rectangular waveguides, filled with homogenous dielectric material, I see that there is always a distinction between TE and TM modes. I understand that ...
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Why is the intensity function of $N$-slits interference symmetric?
I'm taking a course of quantum physics and we were asked to plot the intensity function of interference between the waves which exit 20 slits, when the distance between the slits is given by $$ d+A\...
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X-ray intensity and the dependence of that intensity on the atomic position
I am currently studying the textbook, Solid-State Physics, Fluidics, and Analytical Techniques in Micro- and Nanotechnology, by Madou. In a section on X-Ray Intensity and Structure Factor $F(hkl)$, ...
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Amplitude of a wave, and boundary effects
I am curious as to what causes a discrepancy in the amplitude between the incident and the reflected/transmitted pulse. (* For instance, in the first image, the incident pulse seems to be of greater ...
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Wave equation on Air- Solid interaction
Suppose that there is, due to an explosion $h$ meters above the ground, a wave in the air with high density, velocity and pressure, capable of inducing an elastic wave on the earth's surface. How does ...
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Deriving the longitudinal sound wave from the transverse string vibration
I am trying to derive the longitudinal sound wave (i.e. either the pressure $\psi_P(x,t)$ or the displacement $\psi(x,t)$, where both $\psi$s are in the direction of $x$) produced by the vibrations of ...
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Can I compute mass of an object in a box based on the sound the object makes when shaken? (Barton Fink movie)
In this movie called "Barton Fink" the main character, Fink, is given a mysterious box with an object inside it, he shakes the box up and down, is it possible to calculate the mass of the object ...
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Can our eyes and ears detect phase information in addition to amplitude and frequency information?
Both eyes and ears detect continuous waves that impinge upon them - electromagnetic waves in the case of eyes, and sound air pressure waves in the case of ears. The amplitude of these waves is ...
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Quarter wave matching layer of a piezoelectric transducer
I am trying to understand the quarter wave matching between two layers of impedance $Z_1$ and $Z_2$, where $Z_1 > Z_2$. I can understand the electrical transmission line analogy of matching layer ...
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What is the difference between "normal mode" and just "mode"?
So in the oscillation problems, is there difference between "mode" and "normal mode"? I know that "normal modes" are independent and orthogonal, so one doesn't affect the other. Now I am not sure when ...
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What determines how much power goes into each diffraction order?
Imagine a grating with infinite number of slits, and the spacing D between slits is larger than the wavelength so that there are high order diffractions. In each of the diffraction directions the ...
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Envelope of wavepacket and group velocity
In this answer a possible derivation of the group velocity is provided.
It is, anyway, based on the assumption that there will always be a point where all the cosines will sum with the same phase:
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What is the difference between microscopic quantum interference between photons and macroscopic interference between laser beams?
To get interference between laser beams we use an interferometer composed of mirrors and one beam splitter.
To get interference between photons we use an interferometer composed of polarizers, ...
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Can d'Alembert's Formula for the Wave Equation in one dimension (1+1D) be used in three dimensions (3+1D)?
The 3+1D wave equation for spherically symmetric waves is
$$\frac{\partial^2 u}{\partial t^2} = c^2 \left( \frac{\partial^2 u}{\partial r^2} + \frac{2}{r} \frac{\partial u}{\partial r} \right) $$...
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Proof that fixed points of a null field are zero
Suppose we have a scalar field $V$ (which can be acoustic pressure, or a scalar electric potential) that is a solution of the wave equation
$$\Box V(x,y,z,t) = 0$$
I am wondering if a fixed (non-...
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