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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Stationary Nodes with Waves containing a "Fourier series" of frequencies

For a standing wave (i.e. a wave pattern created from two oppositely-traveling waves with the same amplitude and frequency), stationary nodes are created at certain positions along the wave with ...
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Can we get the discretization of $k$ due to boundary conditions by solving wave equation using Fourier transform?

I am interested in vibrations of a string in different modes with its two end fixed. But I want to use the method of Fourier transform rather than the method of separation of variables. Using the ...
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Thin film interference equation confusion

For thin film interferences, why is that when you have two phase changes, the equations you use for constructive and destructive interferences are switched?
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Is there a general equation for the signal velocity?

The phase velocity is defined as $v_{ph} = \frac{w}{k}$ and the group velocity as $v_{g} = \frac{\partial w}{\partial k}$. Both can exceed $c$ in some situations. The velocity than can't exceed $c$ is ...
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Fresnel coeficients are for a single interface: 2 waves match 1 wave at the other side; are they valid for multilayers were 2 waves match 2 waves? why

Fresnel coeficients are deduced for a single interface where one imposes the continuity of 2 waves at one side with 1 wave at the other side. In multilayers, except at the exit medium, the continuity ...
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Are the photons in a standing wave moving at $c$?

So, in a standing wave, two superimposed waves produce a wave that remains stationary, with its particles resonating back and forth, right? For instance, in a water wave, two waves moving in opposite ...
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Relation between Frequency and Overtone in Circular Membrane

How does the frequency change along the radius of a circular membrane such as a snare drum (with respect to overtones). If I strike the drum in the center, I will get a frequency. Now how will this ...
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How do water waves scale up as the size of a bathtub scales up?

If I fill a bathtub with water to the point that it is spilling out of the far end of the tub, the waves in the tub caused by the water coming into the basin stabilize at a given height -- roughly two ...
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Poynting Vector Perpendicular to Surface

In Spherical coordinates if we have a source at the origin generating $E$ in the $\hat{r}$ direction and $H$ in the $\hat{\phi}$ direction then our Poynting Vector will be in the $\hat{\theta}$ ...
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In electron-photon Compton scattering should the scattered photon form a 'radiation cone'?

If we imagine a photon as a little bit more wave than particle should it form a cone after being scattered from a let say point particle or what ever an electron could possibly be? As the electron has ...
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What happens to vertical light in light diffraction experiments?

In single slit experiment, light tends to bunch up vertically the more it spreads out horizontally. Why does this happen?
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In a string performing wave motion

In a string after the wave is generated, oscillation energy is transferred in the pulse due to workdone by tension. Now,for an electron being a wave what force transfers it's oscillation energy?
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Why do only bass sounds (muscle cars and subwoofers) shake the environment?

I have read this question: The walls have their resonant frequencies and being large objects, these tend to be low frequencies. Therefore bass sound waves are better at triggering resonance in the ...
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Speeds of incident, reflected, and transmitted waves at the joining point of two strings

Consider two strings, with different densities and impedances, connected at $x=0$. The displacement of the left string is given as the sum of the functions of the displacement of the incident wave $\...
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Phase difference of a periodic wave

Can the value of a phase difference be more than 360°? For example, if I want to calculate the phase difference between a point on a wave cycle and another point of another wave cycle. Do I need to ...
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Driving and terminating a wave on a finite string

According to my textbook, in order for a wave to propagate through a finite string as if the string were infinite, the driving force is required to be equal in magnitude and opposite in direction to ...
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Derivation of longitudinal wave in a solid rod

I am trying to understand the derivation of the wave equation for a longitudinal wave in a solid rod (with a given Young's modulus). One of the derivations gives the two forces acting on a solid ...
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Can someone explain what this picture is about please?

From https://www.feynmanlectures.caltech.edu/I_51.html just to illustrate a point, we will try to analyze the speed of such a so-called bore, in a channel. The point here is not that this is of any ...
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Why wavelength increases away from the source of a water ripple? [duplicate]

Hi readers, I have been thinking why the wavelength of water as it gets farther from the source since V=frequency*wavelength. This means that if it gets farther way, the wavelength increases which ...
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Wave equation transverse wave

So guys my question is that when we consider the a sinusoidal wave equation of a transverse wave, for example $$y=A \sin(\omega t-kx)$$ then let's say at $x=L$ and at time $t=0$ when the wave has not ...
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Wave Interfernce of sub-atomic particles

We know that sub-atomic charged particles, proton and electron, emit EM radiation as they are constantly vibrating. Do these particles having equal and opposite charges emit EM radiation in wave form ...
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Why does dispersion occur?

In a vacuum, electromagnetic waves of all frequencies travel with the same phase speed, so they propagate with a fixed shape once determined. In a dispersive medium, waves of different frequencies ...
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Formula for deriving the center of a wave packet from Thorne&Blandford

I am just going through the 6th chapter of Thorne and Blandford's Modern Classical Physics and got stuck on a formula (circled and red) which the authors use to calculate the center of a general wave ...
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Is there a hard clear division between a particle and a wave? [duplicate]

My limited understand is that photons can we both or is a particle and a wave. But they have 0 weight(?) I found this quote today: "Quarks, like all elementary particles, are excitations of a ...
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Apparent inconsistency in wave-optics

$\renewcommand{\vec}[1]{\boldsymbol{#1}}$ $\renewcommand{\hvec}[1]{\hat{\boldsymbol{#1}}}$ In Optics f2f, the author solves for the phase of the a plane wave of frequency $\omega$ propagating along $\...
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How is a sound wave sped up electronically?

Sound waves are recorded as waves electronically. What I am asking is how these waves are 'sped up'. For example on a sound software, when you get a sound wave and then speed it up (using some editing ...
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Wave Interference, question on diagram

I'm trying to understand the wave behavior of light and have questions on diagrams of it. Wiki shows the following two diagrams from Christian Huygens describing the wave nature of light. I have ...
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Longitudinal Wave in 3D - strain/stresses

If a longitudinal wave is passed through a 3D isotropic body, the following strain tensor results [Reference]: This describes the strain in the x-direction while the strains in the y-and z-directions ...
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Can "solitons" be explained by linear wave equation? [duplicate]

In this Wikipedia page about the history of solitons, the author say that the observations made by Scott Russell "could not be explained by the existing water wave theories" at that time. ...
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String vibration patterns

Sometimes when you pluck a string on a stringed instrument, the string turns into what looks like a nearly stationary loop with a semi-transparent middle. Sometimes, the loop doesn't appear stationary,...
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Where does the body gets energy to vibrate in its natural frequency?

If a body is in vacuum and clamped at one point when disturbed slightly from its rest position , starts vibrating. It vibrates in its natural frequency and constant amplitude. So if we are disturbing ...
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Can interference take place if the medium between the slits and screen is changed?

In Young's double-slit experiment, the medium between the slits and screen is usually air. But, if we replaced air with another medium, for example water, the wavelength of light would change and the ...
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Why does rainwater form equidistant waves on an inclined road? [duplicate]

It was raining down on this hairpin road, while I took this image. There was some very interesting waves forming with more or less equal spacing between each other. Also, if you could walk along the ...
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Trying to prove the wave equation from circle

Imagine one of the point in the wave. It is in oscillation. So its displacement can be written as $Y = A\sin(\theta)$ where $\theta= \omega t$. $$Y(t)=A\sin(\omega t) \tag{1}$$ Time for one wave ...
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Can standing waves be formed from a medium with one free end?

I know that standing waves are normally formed in a confined medium where both ends are fixed. However, I wonder if standing waves can be formed in a medium with one fixed end and one free end since ...
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Electromagnetic field potentials

Good afternoon for everyone. I have a question in attitude towards the electromagnetic potentials. There are two terms showing two forms of Maxwells equations for electrostatic potential and vector ...
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Longitudinal wave propagation in 3D

When a longitudinal wave is sent through a body, there is a strain in the emitted direction (x). What about the three-dimensional body with the strains in the direction perpendicular to the emitting ...
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Can we obtain the wave velocity and particle velocity relation from the wave equation?

Let the wave equation be $u(x,t)$. If it is an equation of a wave $\Rightarrow u(x,t) = u(x+c\triangle t,t+\triangle t) $ $\Rightarrow \frac{\partial u}{\partial t} = -c\frac{\partial u}{\partial x} ...
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Transverse and Longitudinal waves

I am performing an experiment where a steel ball of diameter 7.5 mm is dropped by hand on an aluminised kapton foil. Four piezoelectric sensors are placed 55 mm away from the edges at a 45 degree ...
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Why the phase shift of an electromagnetic wave or light after reflection is smaller than 0, being in the range $[-\pi, \pi]$?

In some reports, the phase shift becomes in the range $[-\pi, \pi]$, for instance on this website. However, Wikipedia gives the range as $[0, \pi]$ instead. Which one is correct?
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When is diffraction most pronounced?

My notes says the following things about diffraction: The larger the ratio of wavelength to slit (or object) width, the more pronounced the diffraction is and the more spread out the wave energy is. ...
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Rope as Communication Media [closed]

I'm a computer student that used to play microcontroller and sensor. I'm not sure whether this topic fits on this site. I'm thinking about using rope as media communication instead of fiber optic. I ...
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Propagation of standing wave

We know wave is just a transmission of energy. In case of mechanical wave, this transmission of energy requires a medium so that the particles of medium can help in transfer of energy. Let us think of ...
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G-mode wave in Stratified Fluid layers

I am currently studying on how internal gravity waves propagate within stratified disks of fluid (function of $y$ as shown in the picture). I am referring to the source written by Jim Pringle and ...
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Single slit diffraction $a\sin\theta=m\lambda$ - why does $m$ have to be an integer?

For example, when $a\sin\theta=3\lambda$, we rewrite this as $\frac{a}{6}\sin\theta=\frac{\lambda}{2}$ and explain that the waves from every pair of point source whose path difference is $\frac{a}{6}\...
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Single slit diffraction formula $a\sin\theta=m\lambda$ when $m=3$

For single slit diffraction, when $a\sin\theta=3\lambda$, this means $\frac{a}{6}\sin\theta=\frac{\lambda}{2}$ so the waves from every pair of point source whose path difference is $\frac{a}{6}\sin\...
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Is wave motion the combined motion of the disturbance and the medium?

Using a textbook slinky as an example, if the disturbance propagates through the slinky from left to right and the particles of the slinky vibrate up and down, does that mean 'wave motion' is also ...
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Computing the analytic solution to the non-homogeneous 3D wave equation

I'm working on solving the non-homogeneous equation numerically. $$ \frac{\partial ^2 w}{\partial t^2} = a^2 \nabla^2w + \Phi(x, y, z, t)$$ with initial conditions $$ w= f(x, y, z) \space \text{at} \...
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Do perpendicularly polarized waves interfere?

In the MIT ME optics OCW slides, it is written that parallel polarized waves do interfere but perpendicularly polarized waves do not interfere. However, isn't circular polarization formed by the ...
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What are the units of wavenumber? With or without radians?

Sometimes, I see that wavenumber units are $\text{m}^{-1}$, but on the other hand, (and by definition of $k = \omega/v = 2\pi/\lambda$), it is $\text{rad/m}$. What is correct?

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