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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Diffraction of matter waves

By considering the De Broglie wavelength of particles, we discover that matter can diffract if passed through openings with itself. This poses a variety of questions, namely Can matter waves ...
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29 views

What discrete form of the wave equation do you need to use to make a wave simulation?

I'm working my way through these blog posts about the wave equation. All has made sense up until now. The wave equation is $$ \frac{\partial^2h}{\partial t^2} = c^2 \frac{\partial^2h}{\partial x^2} ...
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39 views

Can KE and PE of a small element of a transverse progressive wave be maximum simultaneously?

Maybe a string can be taken as an example to produce the transverse progressive wave.
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9k views

What is the fringe separation in Young's double slit experiment?

In the double slit experiment, a pattern of dark and bright bands appears on the screen. Is the fringe separation the distance between two bright bands? Question: In a double slit experiment ...
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5answers
106 views

Does the statement “waves only transfer energy, not matter” violate $E=mc^2$?

I'm beginning to learn a little bit about waves, and I'm a bit confused. It is said that waves only transfer energy and not mass, but doesn't this violate $E=mc^2$?
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35 views

Can anybody explain about phase shift and phase spectrum terms in case of multidimensional signal?

I know about phase of a 1D signal, but when I move into higher dimensions like 2D or 3D etc, it becomes headache to grasp the concept. What do the terms "phase shift" and "phase spectrum" mean in ...
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1answer
52 views

How far can you propagate something, anything, before it becomes 'background noise'?

An electric field, light, a movement of molecules; anything at all. What is the maximum distance they can go before they are 'noise' to an ideal measurement instrument? So if the distance is ...
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1answer
87 views

How does a non-diffracting beam form from a converging ring of illumination?

I am trying to intuitively understand the basics of the supplementary text of a recent publication from Eric Betzig's group on lattice light sheet microscopy (1). I am confused by the explanation of ...
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1answer
14 views

Amplitude Modulation in dispersive mediums

I'm reading the book "Physics of Waves" by Georgi. In section 10.2 he says that to send a signal through one-dimensional dispersive mediums where the dispersion relation is not $\omega(k)=vk$ ($v$ the ...
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1answer
92 views

Path Difference Due to Angled Incident Light

If light incident on a diffraction grating makes an angle $\alpha$ with respect to the normal to the grating, show how $$m \lambda = d\sin\theta$$ becomes $$m\lambda = d[\sin(\theta - \alpha) + ...
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32 views

Does every object, every particle and every thing have it's own resonant frequency?

The principles of resonance are such that the greatest amplitude of a vibrational or electrical wave peak at a certain frequency, and they peak while consuming less power overall to maintain it. I'm ...
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1answer
21 views

How does a film with some thickness without reflection alter a wave's phase

How does the thickness of a film alter the phase of a beam of light passing directly through the film without reflection?
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1answer
45 views

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 ...
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104 views

How do waves have momentum?

A question on a practice test I'm taking is as follows: By shaking one end of a stretched string, a single pulse is generated. The traveling pulse carries: A. mass B. energy C. momentum D. ...
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6answers
512 views

Physics of how the cochlea isolates frequencies along its length?

Can anyone explain the separation of frequencies along the basilar membrane of the cochlea please? (equations would be nice) I understand it being related to the resistance caused by fluid in the ...
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3answers
51 views

How can a wave travel if it is spread over all space?

The wave equation in one-dimension is $$\nabla^2\psi = \dfrac{1}{c^2} \dfrac{\partial ^2\psi}{\partial t^2}$$ and in one dimension one possible solution to this equation is the function ...
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2answers
41 views

Would passing horizontally polarized light through a varying width vertical slit allow you to measure the amplitude of light? [duplicate]

I have found closely related questions on StackExchange, but (surprisingly) not this exact question. Seems some answers say individual photons do not have amplitude, only when traveling with other ...
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1answer
34 views

How to compute phases of the signals?

Let us take 4 signals which are sinusoidal and periodic. Suppose you are given a phase spectrum or (/and) equation of the (main) signal only and you are said that the given (main) signal is formed of ...
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0answers
24 views

Problem on string vibration [closed]

Given the standard wave equation for small amplitudes, we have been asked to find the position of string y(x,t), given: (i) y(x,0)=sin x, and, (ii) y'(x,0)=cos x, where y' depicts partial derivative ...
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24 views

How can we calculate the spherical wave vectors L,M,N [on hold]

if we have a vector wave function in spherical coordinates ae^ikz. then how can we calculate its spherical wave vectors M,Nand L
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16 views

Finding skip distance/one-hop distance for a radio wave?

I've been racking my brains all afternoon trying to figure this out. Here's the question we're given: At an altitude of 400km is the reflective layer in the atmosphere. What is the maximum distance ...
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1answer
42 views

If EM waves are made of oscillating electric and magnetic fields, how come photons have no charge?

I just recently learned that electromagnetic waves are made of oscillating electric and magnetic fields, and I have a question. In the standard model, photons are described as having zero charge, and ...
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1answer
26 views

Is this a standing or moving wave?

The electric field of a uniform plane wave traveling in a source free region of free space is given by: $ \vec E= (0.5j \vec x + \vec y)(e^{j \beta z} - e^{-j \beta z})$. Is this a traveling wave or ...
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1answer
546 views

Deriving the group velocity of a wave produced by some basic cosine waves with unequal amplitudes

Consider some basic cosine waves of the form ${E_i} = {E_0}\cos ({\omega _i}t - {k_i}z)$ with different amplitudes, frequencies and phases. We know a combination of such waves could result in a wave ...
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10 views

What is the effect of a magnetic field on a plasma speaker?

I have been doing some research for the past couple years investigating the effect of a magnetic field on a plasma speaker. More specifically, if you apply a relatively uniform magnetic field in no ...
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1answer
26 views

Wave velocity dependence on frequency

Is the velocity of a wave dependent or independent of its frequency? I cannot figure this out on my own. I've asked friends and they do not know.
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1answer
37 views

D'Alembert Equation and standing wave

As we know the d'Alembert Equation is $$ \frac{\partial^2\psi}{\partial x^2}=\frac{1}{c^2}\frac{\partial^2\psi}{\partial t^2} $$ for an undimentional string. Now if we seek standing wave ...
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Disadvantages of viewing a diffraction grating at larger order?

If you are using a diffraction grating as a spectrometer you are likely to use high order, because you have a better resolution (as a result of larger dispersion??). But are there any disadvantage? I ...
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1answer
20 views

Polarisation by Reflection - oscillation direction

I'm currently studying polarisation by reflection, and have come across two pieces of information from the same source, which I can't seem to understand on how they differ. The oscillation direction ...
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1answer
33 views

Why does a good conductor shows pronounced skin effect?

I am currently studying transmission of em waves and skin effect is puzzling me. Let us consider an em wave propogating in z-direction with electric field in x-direction & magnetic field in ...
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3answers
251 views

How does one determine whether an object will make an EM wave refract in a qualitative way?

for example, i have a vague notion that the actual answer is that the permittivity and permisivity are different in each different material, so all waves refract at every boundary, but we only call it ...
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2answers
162 views

Light wave crossing media and the relationship between speed, wavelength, and frequency

There are many threads on this topic (like this one) but one aspect about the equation $ v = \lambda\nu $ still confuses me. I have read that frequency does not change when light crosses into ...
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1answer
65 views

Wave properties and temperature

Today it was told me that wave properties of a particle increase if the temperature decreases. I'm surprised because I have never listened a similar thing, but I think that it's very interesting. ...
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35 views

Calculating the energy of a string wave with different phase and group velocity/amplitude/etc

(Please note this is mostly a theoretical, mathematical question, not one about specific particles. Let me know if this is more appropriate in Mathematica) The energy per wavelength of an ideal ...
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513 views

Would fog impair echolocation abilities?

I was driving down a major highway today and the fog was thick enough I could barely see 40 ft in front of me. I then wondered if I had had some other form of perception could I have perceived my ...
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1answer
29 views

Energy Proportional to the Square of the Amplitude

I don't understand how the energy of a wave is proportional to its amplitude squared...For example, if we consider simple harmonic motion at the maximum displacement, there is no kinetic energy and ...
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1answer
66 views

Derivation of group velocity?

In the standard simplified derivation of group velocity (which can be found here) we use two waves $$y_1=A\sin(K_1x-\omega_1 t)$$ $$y_2=A\sin(K_2x-\omega_2 t)$$ In the proof we then get ...
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5answers
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Do the electric and magnetic components of an electromagnetic wave really generate each other?

Frequently when EM waves are taught, it is said that the change in electric field causes a change in the magnetic field, which then causes a change in the electric field, and so on and so forth. But ...
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3answers
8k views

Do light and sound waves have mass

I have been reading Hawking's 'A Brief History of Time' and it has gotten me thinking about Einstein's theory of relativity, in that it assumes that an object must have infinite mass if it is to be ...
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1answer
493 views

Wave superposition, is my textbook wrong?

Here's the question: Two coherent electromagnetic waves are incident simultaneously at some point in space. The intensity of each independent wave is $I_0$. What is the intensity of the superposition ...
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1answer
126 views

How does a longer wavelength penetrate deeper with Rayleigh waves?

I'm struggling slightly to understand this idea. I've slowly been building up an explanation, so at this stage it might be just some confirmation I'm looking for, but also some guidance if I'm off ...
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1answer
69 views

Light follows the shortest path, but to where?

I'm a high school student and I'm trying to understand why waves bend when they refract. I read a few answers on the site, and the explanation that they follow the shortest path makes sense enough to ...
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1answer
36 views

Unsmooth behavior of water waves

I happened to come across this rather interesting picture of a very deformed (or perhaps intricate) wave. The structure looks like it illustrates a superposition of multiple waveforms, as intuitively ...
2
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1answer
106 views

Diffraction and $k$-space

Regarding diffraction I am a little bit lost reading about reciprocal space and the space of $k$'s. As I understand it the Fourier relationship between a wavepacket $\Psi(\vec r,t)$ and the complex ...
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1answer
34 views

Question about group velocity and travelling waves

I'm trying to learn some basic quantum mechanics and I have a question related to group velocity of a travelling wave. I know there are already a few questions related to group velocity, but I ...
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1answer
78 views

Cavity dynamics from traveling waves to standing waves

This is a question on mathematical physics. The conventional reasoning about the characteristic wave modes in a cavity is to apply the boundary conditions, namely, wave amplitude is equal to 0, and ...
4
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1answer
54 views

Speed of sound in an inifinitely dense medium

Curious thought i just had. The speed of sound is affected by a few factors, but the density plays a large role. As density increases, does this mean that sound could approach the speed of light? If ...
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2answers
4k views

Why do longitudinal waves travel faster than transverse waves?

I have learned that if a medium can transmit longitudinal waves and transverse waves, then the longitudinal wave will travel faster. Why is this the case?
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1answer
132 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?
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1answer
25 views

Disparity between two texts on intensity and phase interference - which is right?

So, I'm learning phase interference. Imagine we have two waves. $$ E_1 = A_0sin(wt) $$ and $$ E_2 = A_0sin(wt+\phi) $$ With $$ \phi = \frac{2\pi}{\lambda}dsin(\theta) $$ Which is the path ...