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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34 views

Gravitational wave physics and their nature [closed]

I have recently learned about and have derived gravitational waves from general relativity while watching a lecture. I have many questions. All the professor did was show the nature of the metric ...
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How to detemine the phase profile of a time-harmonic planar field incident upon a lens rigorously?

$\renewcommand{\vec}[1]{\boldsymbol{#1}}$ $\renewcommand{\hvec}[1]{\hat{\boldsymbol{#1}}}$ 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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Finding speed of a wave [closed]

You and a friend are in a wave pool, and are 6.0m apart. When you are on a crest, so is your friend and there are 3 crests in between you. If you move up and down completely in 0.75 seconds, what is ...
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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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Propagatuon 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?

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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Birefringence in uniaxial materials

In linear optics, when treating anisotropic uniaxial materials we get the frensel equation this equation gives us two solution for n. My problem is that according to Snell's law, if I have two ...
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Negative coherence

I am constructing the interference of two Gaussian wave packets onto which I apply a complex phase, attempting to obtain the coherence measure C (how well they overlap). The $\Delta x(T)$ term in the ...
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Why is there more energy in a gamma wave vs. lower frequencies?

If energy is a function of frequency and amplitude, why are microwaves and lower frequency waves considered “less energetic” than gamma waves only as a function of their frequency and wavelength?
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Do electromagnetic fields propagate continuously? [duplicate]

Having learned about plancks constant it is easy to mentally assign a grid-like structure to reality, almost starting to think of it as being pixellated in a way. This raises the question in me though ...
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Water profile under effect of acoustic pressure (fluidostatic)

I was wondering how to calculate the profile of the water when it is subjected to a focus acoustic wave propagating in air. In particular, let's assume that an acoustic wave is propagating in air and ...
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Standing Waves: question on guitar string behavior [duplicate]

Wiki shows the fundamental and first overtone frequencies as follows. I'm trying to relate these to a vibrating guitar string and interference. I'm assuming these animated images represent the ...
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Longitudinal waves

We see that, in longitudinal waves, particles move to (forward) and fro (backward), but why? When a particle has been shifted forward, why will it even come back and vibrate around it's initial ...
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Dark fringes in the bright fringes while doing Young's double-slit experiment

The above image shows the bright and dark fringes that I got while doing Young's double-slit experiment. Increasing the distance of screen from the slit increases the width of the bright fringes. So ...
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If a spherical wave is described by $\psi \left(r,\:t\right)=\left(A\:\frac{cos\left(kr-\omega t+\phi \right)}{r}\right)$ , is it a function of time?

If the wave equation is $\psi \left(r,\:t\right)=\left(A\:\frac{cos\left(kr-\omega t+\phi \right)}{r}\right)$, and $k=\frac{\omega }{v}$, and $t=\frac{r}{v}$, wouldn't that give: $\psi \left(r,\:t\...
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What does 'rotating vector addition' mean in this context, and how does it generate AM and FM?

I am currently learning about wave modulation. In communication theory, it is said that 'rotating vector addition' generates AM (amplitude modulation) and FM (frequency modulation). What does '...
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Why are waves formed in a string?

Perhaps this is a very naive question. If that is the case, I apologise.(I would still like to hear your answer ). Assume that I took the end of a very long string and moved it up and down. A number ...
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Find the frequency of the first two harmonics of a vibrating string

I have a string of length $2 \;\text{m}$ and the wave velocity is $120 \;\text{m/s}$, find the frequency of the first two harmonics. My attempt, what I must do is to solve the wave equation on the ...
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Analog Is Digital (Discrete)?

As I started reading a bit about analog vs digital signals, I keep returning to this thought. This could be something pretty obvious to the pros out there, but is it safe to assume that underneath it ...
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What is 'optical phaseshift'?

In interferometry, it is said that lasers can be used to measure the 'optical phaseshift' of something. I am familiar with the concept of phase in the context of waves, but I don't understand exactly ...
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The wave equation for electromagnetic wave in a non-uniform region

I am looking for the wave equation for an electromagnetic wave in a non-uniform region but there is a really a few resources online, here is some: What is the difference between a uniform and an non-...
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What causes the undistorted propagation of picosecond THz pulses not to be possible for circular waveguides?

When reading about the concept of circular waveguides, I came across the following statement that I am struggling to undertand. "(...) for circular waveguides the undistorted propagation of ...
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What's the distance required for an omnidirectional wave of light of the highest possible amplitude to reach the lowest possibly measurable amplitude?

I'm interested in finding the distance it takes a single omnidirectional pulse of light of a given wavelength under ideal conditions to spread out from the highest possible amplitude to the lowest ...
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Phase and group velocity - deriving phase changes into animation

I have a question about the phase and group velocity topic. I am making an animation in Python showing both group and phase velocity changes. Let's assume we have 2 waves: $y_1 = A\cos(w_{1}t-k_{1}x)$ ...
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How does time translational invariance and linearity imply irreducible solutions?

The author of the book THE PHYSICS OF WAVES has mentioned on page 69, at the start of second last paragraph, that The point is worth repeating: Time translation invariance and linearity imply that we ...
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Why is acoustic intensity inversely proportional to density of the medium?

The definition of sound (acoustic) intensity is given by $$ I = {p^2 \over {\rho c}} \;\;\;\; \text{or} \;\;\;\; I = {p^2 \over {2\rho c}}$$ I've seen both definitions in different textbooks and am ...
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Double Slit Interference pattern - horizontal or vertical?

What determines whether in a double slit experiment the interference pattern will be horizontal or vertical for example? Is it mostly seen horizontal because the slits are small enough horizontally ...
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Bandwidth in beatings

Im sudying this concepts, but i doesn't find anything clear about it, because I don't have a clear interpretation of the bandidth concept, and the number of bands in a beating wave. $\bullet$ ...

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