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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Rope waves with a twist

In the picture you see a person walking a slackline. A slackline is a tensioned flatband of polyester. Typical tensions are between 1 kN to 15 kN depending on the length of the line. The lines are ...
8
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5answers
397 views

Which formula for the de Broglie wavelength of an electron is correct?

So, I have my exams in physics in a week, and upon reviewing I was confused by the explanation of de Broglie wavelength of electrons in my book. Firstly, they stated that the equation was: $\lambda = ...
0
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1answer
166 views

Energy and the modes of standing waves

If you induce a higher mode in a standing wave, does the wave then carry more energy? If so, does that differ for a mechanical or EM wave? (Perhaps I should elaborate on why I am asking this ...
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9 views

Explain quality factor and bandwidth [duplicate]

Can anyone explain concept of quality factor and bandwidth with a mechanical example?
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0answers
17 views

Wave drag explanation

I was reading a book and came across a definition, wave drag is the resistance from the waves created on the water surface by a moving object. I can't get it. Can somebody explain it with a diagram. ...
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0answers
32 views

Why does thicker aluminum do better at reflecting wifi

I have performed a experiment based one the ability of aluminium reflecting wifi radio waves. I have found out that the more aluminium foil i put on my reflector, the better result I can get. I did up ...
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13 views

What is the relation between rhymes in terms of their wavelengths?

How are the wavelengths of any 2 rhyming words related? Eg: How is the wavelength of the sound produced bye 'fee' related to the sound produced by 'see'?
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1answer
84 views

Is meters per second equivalent to seconds per meter?

I know this question is probably ridiculous, but bear with me for a moment. This thought emerged while I was converting between nm and wave numbers ($\rm cm^{-1}$). In order to prove this conversion, ...
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20 views

How does cavity resonance produce EM waves?

My understanding is it acts like a capacitor and inductor in a loop. The capacitor releases stored energy which is absorbed by the inductor through a magnetic field which then returns it to the ...
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2answers
126 views

A plane electromagnetic wave - phase change - amplitude

A plane electromagnetic wave has the shape: $\vec{E}(\vec{r},t)=E_0\cdot cos(\vec{k}\vec{r}-\omega t)\cdot \vec{e}_y$ $\vec{B}(\vec{r},t)=(B_1\cdot cos(\vec{k}\vec{r}-\omega t)+B_2\cdot ...
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0answers
16 views

Solving traveling wave using the shooting method

The spatially-dependent Hodgkin-Huxley equation for a cylindrical dendrite or unmyelinated axon: where $\frac{a}{2\rho}\frac{\partial^2V}{\partial x^2}$ is a diffusion term $a$ is the fiber radius, ...
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3answers
109 views

Waves - determining whether a given formula represents a wave

Well the basic formula of a wave needs to contain $$y(x,t) = f(x \pm vt)$$ where the sign depends upon the direction of propagation of the wave. However, not every function in the form $y(x,t) = f(x ...
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21 views

Simple harmonic waves

When a simple harmonic progressive wave is travelling through medium,then each succeeding particle lags in phase before the preceding particle.Can anyone expain how does it lag? Thanks…
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47 views

Plucking Guitar Strings [on hold]

I was given this prompt: A musician frets a guitar string of length 1.5 m at x = 0.28 m with one finger, and simultaneously plucks the string at x = 0.14 m with another finger (raising it to a height ...
0
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1answer
172 views

Acoustical wave equation from Hamilton's principle

It is common to show the features and power of the Hamilton's principle by deriving the equation of vibrating string, membrane etc. using this principle. But I have never seen that used for deriving ...
0
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1answer
19 views

Is it possible to low pass filter the amplitude of a sound wave?

Is it physically possible to block or attenuate noise above a certain amplitude, but leave other lower amplitude noises unhindered?
0
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1answer
21 views

Can you have a problem with a Dirichlet boundary condition but with waves that reflect off the boundary?

Say we are looking for a solution to the Helmholtz equation $$(\Delta + k^2) u = 0,$$ in in the upper half space ($y > 0$) in 2D with a Dirichlet boundary condition on the $x$-axis, that is, $u(x, ...
6
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3answers
96 views

Transverse simple harmonic wave travelling in a string [on hold]

This question came in my exam. My Attempt: I thought that the tension will not vary in the string because since we know that velocity of wave in a string is given by $$v=(T/m)^{1/2} $$ where $v$ ...
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0answers
25 views

How to solve the following wave equation? [on hold]

We have paraxial beam propagating in a uniaxial anisotropic media. When such is the case wave can be divided into two orthogonal parts: Ordinary wave beam Extraordinary wave beam. The ordinary ...
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1answer
343 views

Particle displacement at a rarefaction or compression

In a longitudinal wave, why is there zero particle displacement at a compression or rarefaction and maximum displacement at a point pi/2 from it? Shouldn't it be the other way round?
3
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3answers
72 views

Why is the Plane progressive wave equation $y= a\sin (kx-wt)$ for positive direction of x-axis?

Likewise, why is $y= a\sin(kx+\omega t)$ for negative direction? What is the basis/derivation for this?
9
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2answers
284 views

Explanation of the waves on the water planet in the movie Interstellar?

We will ignore some of the more obvious issues with the movie and assume all other things are consistent to have fun with some of these questions. Simple [hopefully] Pre-questions: 1) If the water ...
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2answers
31 views

What is the player's role in the functioning of a theremin?

I recently see a video on how the theremin works, and wasn't satisfied with the answer. I watched around, but they all seem to give the same explanation. A diagram as below is given, and it is ...
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3answers
707 views

Don't all waves transport mass?

How do matter waves not transport mass? I know that matter waves are associated with moving sub-atomic particles(which is insignificant for macroscopic particles). If a wave is associated with a ...
2
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1answer
29 views

Wave Velocity vs. Phase Velocity

I am trying to understand the difference between 'wave velocity' and 'phase velocity'. I know that generally they are equal, but when is that not the case? I, of course, tried to google it, and ...
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1answer
40 views

How do waves transfer mass?

A similar question was asked here, however the discussion was led astray by involving the equation $E=mc^2$. I know that waves transfer energy, but do they transfer mass? And, if they do, what would ...
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10 views

Energy density of a transverse

I'm finding it hard to understand the concept of energy density of a transverse wave. I know the formula, but I can't quite get my head around it. I know energy density is energy over volume, but ...
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1answer
38 views

Derivation of the wave equation from Hooke's law- Generalization question

Following the derivation on the relevant Wikipedia page, I am having a bit of trouble moving from the following line, with the case of 3 particles in a row: $$ \frac{\partial^{2}}{\partial t^{2}} ...
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3answers
20 views

Is the speed of a wave determined by the medium in which it travels, the frequency of the source, or both?

I know that for a string of linear density $\mu$ and tension $T$, the wave speed is given by $v=\sqrt{\frac{T}{\mu }}$. Additionally, the speed of any sinusoidal wave is given by $v=\lambda f$. My ...
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3answers
68 views

An experiment to show sound waves

My 6 year-old son asked me to explain the sound barrier. I think I'm ready to explain, but I wanted to know if I could add a little homemade experiment to show visually how soundwaves are generated. ...
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1answer
37 views

How to find net wave formed by superposition of two waves with different amplitudes and different frequency? [closed]

The original question was: Choose true or false for each options. The equation of two sound waves are given by $$\begin{align} y_1 &= 3 \sin 100\pi t \\ y_2 &= 4 \sin 150\pi t ...
3
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2answers
184 views

Is it better to call the doppler effect a change in wavelength or frequency?

Why is it preferable to say that the doppler effect causes a shift in frequency rather than a shift in wavelength? I often read on websites that they define the doppler effect as a change in ...
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2answers
80 views

Do mechanical waves also carry momentum as well as energy? [closed]

I have read that electromagnetic waves carry momentum because they carry energy, while energy is equivalent to mass. So they carry momentum. But this explanation is in the context of special ...
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1answer
15 views

When should I use the phase constant in the equations of waves?

In the equations of Waves, I find that somewhere they have used the phase constant and somewhere haven't. While deriving the formula of standing wave they assumed two equation as $ y_1\; =\; y_0\, ...
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4answers
55 views

Is the speed of sound in air constant?

In Optics lecture we took a formula for the speed of a wave which is: $$ v=\frac{\omega}{k} $$ where $\omega$ is number of complete vibrations per second: $$ \omega=\frac{2\pi}{\tau} $$ and: $$ ...
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3answers
273 views

Why a ship can't pass through its own wave?

This is a photo of a container vessel. All container vessels are long because they are cruising at high speeds. When a ship is sailing it creates waves. When the wavelength of these waves equal the ...
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2answers
69 views

Is Huygens's Wave Theory still correct?

We have to study on details about Huygens's Wave Theory though we have Electromagnetic theory, quantum theory today. Is it still correct or not?
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31 views

Problem in understanding the interpretation of $-T_0\frac{\partial\psi(z,t)}{\partial t}\,.$

I've been reading in Frank S Crawford's Waves, travelling waves and reflection. Here in the following quotes, the author interprets the term $\frac{\partial \psi(z,t)}{\partial z}$: The power ...
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0answers
17 views

Conservation of energy in a sound wave

I have two ultrasonic transducers, an emitter and a receiver, and I'd like to know how the energy of the spherical wave is conserved. I guess the energy is proportional to its amplitude and it ...
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2answers
43 views

Is the wave equation a periodic wave equation?

I have seen that in the derivation of wave equation, they always use the periodic property of waves in the derivation. But what about non-periodic waves? Do they have some different wave equation? Is ...
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2answers
2k views

Why doesn't the magnetic field polarize when polarizing light?

If the magnetic field doesn't polarize does it follow the electric field path of propagation? or does it vanish?
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1answer
50 views

Why are two speakers at the same volume and distance not twice as loud?

If I have two identical speakers facing me which are adjacent to eachother, playing the same music at the same volume, would it be any louder than having just one speaker at the same volume? If not, ...
3
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2answers
44 views

How does a tranverse wave propagate?

Sound waves can be understood as particles hitting each other and to conserve momentum the vibration travels in air. Each particle transfering it's momentum to the other until it reaches our ears. ...
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2answers
41 views

Is a spring shaped like a sine wave?

It's just a casual observation, so I wanted to check it: A regular spring, when not completely compressed, looks an awful lot like a sine wave. The idea of a circular shape stretched out in the third ...
0
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0answers
23 views

Why are photonics fibers called band gap fiber?

Why are photonics fibers called band gap fibers? Do the photonic fibers guide light inside the band gap or outside? What creates the band structure?
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0answers
14 views

How does an increase in temperature change the width of the central bright for Fraunhofer's single slit experiment?

When coherent light shines onto a metal sheet with a thin slit. There will be an interference pattern with a central bright fringe. If the temperature of the metal is increased, this causes linear ...
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4answers
2k views

How to derive the formula for phase difference $\Delta \Phi = \frac{2\pi}{\lambda}\Delta x$?

How can I derive the formula $$\Delta \Phi = \frac{2\pi}{\lambda}\Delta x$$ for calculating the phase difference? On a relative note, why does the particle velocity have an upwards direction when ...
5
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2answers
124 views

Must flow be supersonic for disturbances not to affect upstream?

I'm studying oil production and found a fact that puzzled me. It states that fluid flow downstream of the wellhead must be supercritical in order not to disturb the flow upstream of it. From ...
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1answer
36 views

Failure of Superposition principle at high amplitudes

Why does superposition principle fail at high amplitudes. Please answer with respect to transverse waves. If possible, plane progressive transverse waves at best.