Waves are disturbances that propagate throush 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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Producing photons with same frequency, different amplitude wave [duplicate]

I don't understand how two photons of the same frequency can have different amplitudes, neither how to produce them. I know that classically the square of the amplitude is proportional to the energy, ...
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1answer
36 views

What is the relative speed of the galaxy with respect to the Earth [on hold]

Consider a distant galaxy. Though this is a bit contrived, suppose that an astronomer measures the fourth transition of the Brackett series of transitions from n > 4 to n = 4 in Hydrogen at a ...
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1answer
31 views

Speed of sound and Break the sound barrier

What happens when plane exceeds the speed of sound? and What is the interpretation of the conical shape that appears behind the plane?
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65 views

Heat diffusion: evanescent waves?

It has been recently pointed out to me that the solution of the heat equation in a semi-infinite material with an oscillating boundary condition at the surface is not an evanescent wave. The argument ...
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1answer
127 views

Wave Packet in Curved Spacetime

It is known that the classical equation of motion for a scalar field wave packet on a curved spacetime background gives the geodesic trajectory (the e.o.m. is $(\nabla_\mu \nabla^\mu + m^2) \Phi=0$). ...
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45 views

Diffraction to be explained without Huygens principle

Can we explain diffraction without using Huygens principle?
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Relation between size of obstacle, wavelength and diffraction

"If the boundary is merely an obstacle implanted within the medium, and if the dimensions of the obstacle are smaller than the wavelength of the wave, then there will be very noticeable diffraction of ...
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1answer
26 views

Finding the distance between two osclilating particles in a wave

Assume a wave function $\psi = \psi(x,t)$ where $x$ is position from the starting point $(0,0)$ and $t$ is time. Two oscillating points A and B are located at $x_1$ and $x_2$ respectively with $x_2 ...
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13 views

What equation can be used to solve an ideal string/membrane in a non-vacuum medium?

I'm interested in the eigenmodes of the membrane for various mediums, such as vacuum, air, water, etc., which impose a damping effect on the membrane. This cannot be done by merely changing the value ...
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16 views

Difference b/w angular width and linear width of fringe

In double slit experiment and single slit experiment what is the difference between angular width of fringe and linear width of fringe?
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1answer
80 views

Linear vs. quadratic dispersion relation

In wave mechanics the dispersion relation between frequency $\omega$ and wave number $k$ is linear: $$\omega_n=c k_n$$ But in quantum mechanics, based on Schrödinger's equation, one can show that we ...
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29 views

Meaning of ideal membrane

I'm studying from a mathematical point of view the bidimensional vibrating membrane. How can I define an ideal membrane? What are the assumptions when I say 'ideal'? Thanks!
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Speakers and Changes in Temperature

Let's say that there is a speaker that oscillates the same way. Now, let's say there is a sudden drop in temperature. I know the speed of sound would drop. But, what will drop, the wavelength or the ...
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1answer
24 views

Difference between sound wave and lightwave scattering [on hold]

What are the main differences between sound and light scattering starting with the Helmholtz equation? (Preferably by circular cylinder)
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Boundary conditions for enthalpy waves inside a pipe

So I'm trying to solve a form of the wave equation for sound produced by a vortex distribution $\vec{\omega}$ convecting at velocity $\vec{v}$ . $$\left(\frac{1}{c_0^2} \frac{\partial^2}{\partial ...
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5answers
271 views

What happens to waves when they hit smaller apertures than their wavelenghts?

I was wondering this for quite a long time now. Let's say you have a water wave (like ripples, not the ones you see during tsunamis) with wavelength 10 m. Imagine you put a boundary with an opening of ...
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2answers
776 views

Wave diffraction explanation [on hold]

I'm trying to understand wave diffraction and I found this wikipedia article. It's in Czech so I'll explain a bit. I'm interested in the 4 images I couldn't find on english wikipedia. The first one is ...
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1answer
26 views

Sound Wave interference Experiment

I was wondering, can we use two sound sources so as to create a destructive interference at the position of a recorder at home? If possible, what is the easiest way?
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Frequency dependance of sound wave reflection

Why are high frequencies reflected more than low frequencies off an 'acoustically hard' surface such as concrete? I basically understand that the amount of reflection is determined by the impedance ...
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0answers
12 views

Determining speed of transverse wave [closed]

A transverse wave on a string, given angular frequency $\omega$, wave number $k$ and max displacement from equilibrium $A$. Determine the speed of the wave along the string. ATTEMPT $ v = { \omega ...
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1answer
220 views

Dispersion relation for TE and TM waves in general anisotropic medium

I want to calculate the dispersion relation (the relation between $\bf k$ and permittivity and permeability tensors and $\omega$) for a TE and a TM wave with wave vector $\mathbf k=k_x\mathbf {\hat ...
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2answers
44 views

Superimposed state vs. zero amplitude state

Two equal amplitude wave pulses approaching each other through some medium such as a string may form a region of zero amplitude when they overlap completely. At this point, the location of overlap is ...
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40 views

Physics - Waves (Help!) [closed]

When a microphone is moved along the line LS, the trace seen on the c.r.o. varies from a MAXIMUM amplitude to a MINIMUM amplitude and then back to a MAXIMUM amplitude. Sketch this sinusoidal graph ...
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1answer
45 views

Thin-wedge Interference Problems (Classical Waves Problem)

I would like to solve the problem on the following image: My question is: Why is the answer to (a) a minimum? When the light wave hits the top surface of the top glass, a wave will be reflected ...
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2answers
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Are there any ways to alter frequency of wave?

I want to know how can we change frequency of wave, both sound and light, and what is the nature of "changing frequency" Such as, any material could absorb and re-emit wave in another wavelength. Or ...
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about superposition of two sinusoidal waves

I am reading a material on introduction of interference and superposition. To go deeper, I want to know how the math works in superposition, from wiki ...
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4answers
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Is the existence of electromagnetic standing waves dependent on the observers reference frame?

If I take two plane EM waves travelling in opposite direction e.g. $E = E_0 \sin(kx-\omega t)$ and $E=E_0 \sin (kx + \omega t)$, they sum to give a standing wave with a time-averaged Poynting vector ...
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Can radial mode standing waves exist in a column of gas?

In a solid bar such as aluminum one can excite transverse, longitudinal and torsional standing waves. In a column of gas bound within a tube, whether open-open, open-closed or closed-closed, physics ...
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Distribution of refractive index of water when applied pressure wave

I was wondering when applying pressure wave, ultrasonic sound waves, under water, how I would be able to measure the distribution of the refractive index.
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19 views

Sound vibrations for marine propulsion

I asked a similar question about bubbles making less friction on a mass moving through water, now I'm wondering of sound waves could do the same thing as supercavitation or possibly create it's own ...
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1answer
40 views

Trouble understanding phase matching equation

consider a 2nd order non linear optical material, i.e. a material in which it holds that $ P = \epsilon_0 E + 2dE^2$. In the Born approximation, the non linear contribution to the polarization density ...
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26 views

Modeling the creation of transverse waves

Suppose I hang one end of a jump rope against a wall and start waving the other end. I'm interested in knowing the behavior of the jump rope as it starts generating waves. In other words, how can I ...
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1answer
18 views

Intensity of Sound Wave

Is the intensity of a sound wave same at all the points through which the wave travels? The formula for intensity is $ I = \frac{{p_0}^2 }{2 \rho v}$. But this does not make sense to me. Shouldn't the ...
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1answer
210 views

Does a wave experiencing a total internal reflection penetrate the medium in any way?

Let me explain my concern usingn this picture: At the point of total internal reflection does a fraction of the wave get into medium 2? I would imagine it should happen because of the uncertainty ...
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3answers
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Double-Slit Experiment Separation Between Fringes

I was taught in class that the double slit diffraction pattern would always have bright fringes of same length. We derived the formula: $y=m(\lambda)(L)/d$, which also shows this equal distance. I ...
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1answer
392 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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Why doesn't amplitude affect the speed of sound?

I understand why amplitude doesn't affect the speed of the sound AFTER the 'leading compression'. The extra force provided on one stage of the cycle is countered on the other stage. But shouldn't the ...
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Standing waves on a compound string

I've been having some difficulties in understanding standing waves. The questions that I have are as follows: 1) Suppose I have a compound string, made up of two strings. What is the correct way to ...
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3answers
83 views

How damaging is light? [closed]

On Surely You're Joking Mr Feynman, when talking about the Trinity test, the author states: the only thing that could really hurt your eyes (bright light can never hurt your eyes) is ultraviolet ...
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1answer
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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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28 views

Destructive and Constructive Interference Sign Problems in Sound Speakers

The problem statement, all variables and given/known data Problem b). Looking at the attached document of my teacher, the visual representation of the answer does make sense. Relevant equations ...
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93 views

What makes laminar cascade break?

Near my house there is a mall that have a cascade, which has a pratically constant flow, and doesn't seem to have perturbations (at least near the edge where water falls), between its two levels. ...
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15 views

Appropriate order of the sources in the phase difference formula (Waves)

Please look at b). My teacher defines delta(x) to be x1-x2 and then says that phi naught of 1 =0. However, because she defined the difference to be "1"-"2", the phi naught difference should also be ...
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1answer
33 views

Reflected waves and phase changes

If a wave passes from a lightweight string to a higher density string, we say that the reflected wave has a pi phase change. Can we say that it has minus pi phase change? If yes, why would that not ...
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1answer
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What happens when a slow wave reaches lower hybrid resonance?

Lower hybrid resonance occurs when $n_{\perp}^2$ goes to infinity, and it occurs only for the slow wave solution, not the fast wave. Since $n_{\perp}$ is proportional to $k_{\perp}$, and $k = \frac{2 ...
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1answer
91 views

Questions related to resonance/standing-waves and sound

I understand resonance for a simple harmonic oscillator but not for more complex systems like standing waves. How can I be in resonance with the normal mode in an organ pipe? I understand that the ...
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1answer
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Why is a particular wavelength favored by transmission through a thin film?

A sheet of glass is coated with a $500\text{ nm}$ thick layer of oil ($n=1.42$). For what visible wavelengths of light do the reflected waves interfere a) constructively? b) destructively? ...
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1answer
82 views

Why can we leave off half of the general solution?

In these pdf notes, it says at the bottom of the first page and beginning of the second: [...] whose solution is: $$\Psi(\theta) = c_1 e^{i\omega\theta} + c_2 e^{-i\omega\theta}$$ Since we are ...
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1answer
25 views

Propagation of sound waves and monopole

While it is understood that in order for the acoustic waves to reach far field the wavelength should be less than the characteristic length of the source, I am not able to physically understand how? ...
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24 views

Radar Vs. Sonar

What is the true difference between radar and sonar? My understanding is that radar uses a reflected EM wave, while sonar uses a compression (shock wave) of the material it's in. (It compresses water, ...