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 will be more appropriate to consider sound wave as a pressure wave or displacement wave

I was reading waves from H.C. Verma in which it was written when two sound sources vibrate in unison then at mid point between the sources a pressure antinode is produced but a displacement node . ...
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What is the physical significance of the value of wave amplitude being $1$?

In Feynman Lectures Vol.1, it is written that: First of all, we know that the new way of representing the world in quantum mechanics - the new framework - is to give an amplitude for every event ...
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Does Helmholtz reciprocity holds for partially coherent lights?

Helmholtz Reciprocity describes how light sources and sensors are reversal to each other. In other words, "If I can see you, then you can also see me." My question From Wikipedia's derivations, it ...
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Question regarding different time equations and physics formulas [closed]

Here is a simple problem I believe regarding differential equation which I can't figure out. So the problem says, An electrical signal is sent out with amplitude $3$. & frequency $200$ Hz. ...
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Doubt on calculation of a “general expression” on the energy of a travelling wave in a column filled with gas

I) SOME FACTS When we study mechanical waves, we essentially have to deal with $dm$ mass increments; then we can "expand" they as: $$ dm = \rho(x,t)dV.\tag{1}$$ Also, I think that it's pretty ...
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Sound waves travel with electromagnetic waves?

Do sound waves travel along/with electromagnetism and static electricity from the sun?
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Intuitive explanation for why blue light is refracted more than red light?

I understand the equation explaining angles of refraction related to wavelengths. But I'm looking for a more intuitive approach/visual explanation? Perhaps related to QM?
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EM wavelength in different medium

Considering a light wave traveling from the vacuum to air, I am trying to find what will happen to its wavelength. At first, using optics, we know that: $$n=\frac{c}{v}$$ where $n$ represents the ...
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Source of cylindrical electromagnetic waves

I have a question about waves with cylindrical wavefront. Precisely, I have read that they may be generated by a linear source, while for instance plane and spherical waves are respectively generated ...
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Why do matter waves have superluminal phase velocites?

Specifically why do they have $V = \frac{c}{β}$ as stated in this paper written by De Broglie: http://aflb.ensmp.fr/LDB-oeuvres/De_Broglie_Kracklauer.pdf ? I follow the proof of “phase harmony” ...
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Reflection in stationary waves

A stationary wave is formed by the superposition of two waves with the same frequency and amplitude travelling at the same speed in opposite direction. Consider a wave generated by a vibrator is ...
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Double slit experiment in water: A simple demonstration of refractive wavelength?

The speed and wavelength of light both reduce in media with high refractive index. However, it is perhaps not intuitively clear how frequency and wavelength behave in refractive media. A very simple ...
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Why can't a wave travel in a non-elastic medium?

Why a wave cannot propagate in a non-elastic medium We know that wave is a distrubance and carries energy. In this sense let imagine fall of dominoes, which carries disturbance and energy. Here fall ...
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Find the time period ($T$) for an electric field wave: $E=E_0\sin{m t}\sin{2mt}$ [migrated]

Find the time period ($T$) for an electric field wave: $E=E_0\sin{m t}\sin{2mt}$ I thought $T$ is such that, $E(T+t) = E(t)$. As period of given sinusoidal function $E$ is 2$\pi$, $$ \Rightarrow 2\pi ...
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Why does frequency remain the same when waves travel from one medium to another? [duplicate]

I was reading about reflection and refraction on BBC Bitesize and I can't understand why frequency is a constant in the wave speed equation. I can't visualise the idea of it. I know that wave speed ...
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De broglie frequency [closed]

The de broglie wavelength of matter particle is very low. Does that mean matter is associated with waves of high frequency? If so why can't we detect them?
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Why are there no even harmonics in a closed pipe?

I have seen a diagram on sites such as hyperphysics.com that show that there is a missing bit every time so that it makes every harmonic odd. I was hoping I could get a more intuitive explanation. We ...
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1D wave - impedance & amplitude relation

Consider a string with variant characteristic impedance $Z(x)$. Also $Z$ is a continuous function. We are exciting the edge of the string so that $y(t) = Ae^{iωt}$ at that point. Is it true that if $...
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Reference for Non-Linear Water Waves

In class, my professor just mentioned that some finite-amplitude water waves were satisfied by the KdV equation. Is there some reference which shows how to derive this from $1st$ principles, and also ...
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The relative velocity of sound waves in Doppler effect

Let speed of sound in the medium be $v$ when the source is at rest w.r.t the medium. In the case of the observer moving towards the stationary source with a velocity of $u_1$, the speed of sound ...
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Relation between phase change and mass of bodies during wave inversion

Is there a relation which shows how the phase change depends on the mass of the bodies in mechanical wave inversion? This question also applies to EM-waves and any sort of relation to explain their ...
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1answer
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Wave rate of energy confusion [closed]

Consider we are exciting the edge $x=0$ of a string, so that $ y(0,t) = A\cos(ωt) $. We know that the rate of energy is $$ \frac{1}{2}ρω^2Ac = \frac{1}{2}ω^2A\sqrt{Tρ}$$, where $ρ$ is the string ...
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Difference between alfven waves and magnetic fluctuations in solar corona

I have read in this paper https://arxiv.org/pdf/1911.07973.pdf about particles being accelerated in the solar corona either by Alfven waves (to my understanding when the turbulence is weak) or by ...
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Why does a spinning rod create transverse waves?

I attached a ballpoint pen refill to a DC motor and made it spin very fast. Instead of just turning along its axis, the refill started to wobble around to make a transverse wave. You can see that ...
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Interpretation and computation of properties and polarization of an electromagnetic wave (transverse wave) [closed]

I would like to calculate the polarization properties of a plane wave (transverse electromagnetic wave), based on values of an export file from an electromagnetic simulation. The values are recorded ...
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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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Can a wave undergo SHM?

I am recently studying about Simple Harmonic motion and during that I thought, Do a wave undergo simple harmonic motions ? Do they ?
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Why use solids for soundproofing when sound waves travel through them faster?

I'm doing a soundproofing experiment where I test out different materials with different specific heat capacities to see how SHC affects how much sound level is emitted. But I also know that sound ...
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4answers
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Has a reflected wave an arbitrary phase shift?

Let an EM wave propagate in the $\hat{z}$ direction - $$\vec{E_I}(z,t)=E_0e^{i(kz-\omega t)}\hat{x}$$ it hits a conducting surface at $z=0$ so there is a reflected wave - $$\vec{E_R}(z,t)=E_{0R}e^{i(-...
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Explaining light distribution trough a gap using waves and Huygens principle

According Huygens principle when a light wave goes trough a gap that is so narrow that only one wavelet can pass, it would spread out in all directions like in this image: (image from https://en....
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Mechanical wave transmission through 3 strings of different medium qualities

How would the motion of waves behave if there are 3 strings joined to each other (as displayed in the fig.) and a wave was started in the string-3? Which would undergo inversion of strings and for ...
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Reasons for mechanical wave inversion? [duplicate]

General idea (with strings): When a wave in a string in transmitted through 2 different media, a part of it is inverted and a part transmitted. 'Rules:' If a wave enters a region where the wave ...
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Direction of momentum and group velocity of electron in a solid

So I am looking at the dispersion relation of electrons in a solid i.e. a $E(k_y)$ plot and I am being bugged by a very basic question about wave propagation. If $v_g = \partial E/\partial(k_y) > 0$...
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1answer
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Why do we demand that $\lambda \ll \text{size of slit}$

I'd appreciate it if anyone could explain to me why do we demand that the wavelength will be much smaller than the distances between the slits in order to see wave diffraction when performing Young's ...
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Peculiar Question: Can Sound travel through particles of Light?

It is a thought Experiment. Imagine a box that is lined on the inside with 100% perfect mirrors. Shine some light into that box and seal the box. The light will bounce back and forth between the ...
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If both violet light and red light was incident on the center of a semi circular block, and refracted, would they have the same refraction angle?

As the violet and red light have the same speed in air, with the incident angle being less than the critical, with the violet light and the red light coinciding on each other, (like on top of each ...
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Power spectrum on wavelength

For a peak in hydrogen spectrum, we fit a peak function of Lorentzian. I seeked for an explanation and I found the power spectrum $|f(\omega)|^2$ is in fact the Lorentzian. $f(\omega)$ is the Fourier ...
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What are the phase speeds of $A_0$ and $S_0$ Lamb waves at very low frequencies?

Lamb waves are elastic wave modes in plates. In general, they are mathematically complex to deal with, and numerical solutions are typically used to find dispersion curves for each mode, as shown in ...
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Is there a formula that links between emited sound level (dB) and specific heat capacity?

I'm doing an experiment on soundproofing and seeing how different materials with different specific heat capacities affect the level of sound emitted from a music speaker. Each material is formed into ...
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How to calculate the phase and group velocity of a superposition of sine waves with different speed and wavelength?

This might seem like a trivial question but it is not for me. So, I was reading on group and phase velocities from A.P. French where he calculates the phase and group velocities for a superposition of ...
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Speed of light and wavelength

Does the speed of Electromagnetic wave depend on its wave length? For vacuum I'm aware that it's a constant $c=\frac{1}{\sqrt{\mu_o\epsilon_o}}$. Similarly can we say speed of light in any medium is a ...
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Average value of potential energy and kinetic energy in simple harmonic motion [closed]

In the Derivation of the formula of average potential energy and kinetic energy in simple harmonic motion. Please explain the step in the image.
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Relation between frequencies of different harmonies

I know the relation between frequencies of different harmonies is $$ f_n = n\times f_1 $$ but I'm heving trouble to develope the equation which proves this equality. can anyone please give me a lead ...
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Waves and Alternating Current

What will happen if a metallic spring fixed at one end which is connected to a steel wire of certain length and the other end of the steel wire is connected to an AC source. Shall we see the spring ...
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1answer
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Harmonic waves: direction left or right?

Consider $E(x,t)=A\sin(kx-\omega t)$ where $k=2\pi / \lambda$, with $\lambda$ the wave length and $A$ its amplitude. We have $$E(x,t)=A\sin(k(x-vt))$$ so this wave is going to the right. Know, if I ...
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Does the angle between adjacent maxima remain the same?

Is the angle between adjacent maxima, in this case adjacent rainbows, the same. That is, is the angle made by the First-order rainbow and Central white the same as the angle made by the First-order ...
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Do reflection and diffraction occur at the same time?

When waves pass through a gap as the above, diffraction occurs. As the upper and lower part of the plane wave (indicated by yellow colour) are striking the barriers, does reflection occur at the ...
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Deriving the wave equation for electromagnetic waves

I'm currently referring to the wave equation derivation given in "Introduction to Electrodynamics" by David J. Griffiths. It follows something like this: The electromagnetic wave equations are given ...
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1answer
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Spacing between primary maxima of $N$-slit diffraction pattern and single-slit envelope

As far as I know, in the double-slit diffraction pattern, the spacing between primary maxima is determined by the equation of double-slit interference pattern, and the intensities of primary maxima ...
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Does a particle interact with the slit in diffraction from a single slit?

The wave explanation of the diffraction pattern from a single slit takes in account the interference of the wavelets of all points between the walls of the slit. In effect it turns so that the wave ...

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