# Questions tagged [plane-wave]

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### A parallel between eddy current and Beer-Lambert law

For AC current flowing in wire eddy currents are the reason for current density decay as we move towards the center. Similarly, in Beer-Lambert law, for electromagnetic plane wave impinging on ...
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### Acoustic Plane Wave

Consider an ideal fluid which we have a spherical object on it and a progressive plane wave is heading the object. I have a simple question and it is: If we assume the amplitude of the incident ...
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### Compute SH and SV component in shear wave (accoustics wave propagation)

I'm reading this guy right now. Basically I need to add to a ray tracing simulation components for shear waves propagation (in the acoustic/VHF range). Essentially this is related to section 1.2 of ...
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### Rigorous plane wave expansion in QFT

I work with quantum field theory in curved spacetimes, so I'm not fully aware of the notation used in standard QFT. However, I'll try to make myself clear. In standard QFT, the one-particle Hilbert ...
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### Behaviour at an interface plane wave

I have this example diagram that was given in one of my lectures and I am just going through what the equation given actually mean and calculating some results from the equation. Which are the angle ...
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### Conservation law charge in plane-wave

When considering a charged particle in a plane-wave field, it is possible to show that the 2 following quantities are conserved $\boldsymbol{p}_{\perp} - e\boldsymbol{A}_{\perp}$ and $p_z - \gamma$ ...
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### Plane wave and polarisation

I am trying to understand the concept of a polarisation of a plane wave. Generally, the plane wave can be seen as a sum of two orthogonal linearly polarized waves. according to Wikipedia. So I have ...
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### What is the load reflection coefficient for a uniform plane wave travelling at the boundary between a dielectric and a perfect conductor?

Suppose you have a uniform plane wave travelling from a dielectric medium towards a perfect conductor (suppose the interface is planar as well). From my understading of the theory behind EM waves and ...
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### Plane wave propagation constants being equal across all components

Starting from the wave equation for electric field in free-space, $$\nabla^{2}\boldsymbol{E}+k^{2}_{0}\boldsymbol{E}=0,$$ where $k_{0}$ is the free-space wavenumber, we usually proceed in deriving ...
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### What is the logic behind box normalization and periodic boundary condition?

Free particle energy eigenfunctions are $A\exp{[i(Et-\textbf{p}\cdot\textbf{r})/\hbar]}$ are non-normalizable. To normalize them one introduces a procedure called 'box normalization' where one imposes ...
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### Proof of non-orthogonality E and H fields of an electromagnetic wave in certain materials?

I understand that electromagnetic waves must have orthogonal E and H fields in free space from Maxwell's third equation. However, I saw on a Quora post that these fields do not necessarily have to be ...
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### Is a plane wave necessarily monochromatic?

Is the expression $$\psi(x,t)=A\exp{i(kx-\omega t)}, \hspace{0.3cm}A=\rm constant$$ the most general form of the plane wave? If yes, does it mean that a plane wave is necessarily monochromatic? If ...
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### What are plane waves in Bethe ansatz

I study Bethe ansatz, although my background is mathematics not physics. Can somebody explain to me what is plane waves? I have seen in many papers this expression that "The idea of the Bethe ansatz ...
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### Wave packets and the uncertainty principle

In my lecture course, I am told that a wave packet $\varphi$ is a superposition of plane waves such that $$\varphi = \int a(k) e^{ik-iw(k)t} dk$$ The function $a(k)$ is then linked to probability and ...
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### Magnetic field of a plane wave hitting a conducting surface

If the $E$ component of a plane monochromatic wave does not penetrate the conducting surface, what happens to the $B$ component? The $E$ field gets reflected back because we are talking about a ...
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### Describing travelling waves carrying energy from one point to another

A simple harmonic wave in one-dimension (for simplicity) $y(x,t)=A\sin(\omega t-kx)$ in a medium is often presented as an example of a travelling wave. But such a plane wave is infinitely extended ...
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### Can d'Alembert's Formula for the Wave Equation in one dimension (1+1D) be used in three dimensions (3+1D)?

The 3+1D wave equation for spherically symmetric waves is $$\frac{\partial^2 u}{\partial t^2} = c^2 \left( \frac{\partial^2 u}{\partial r^2} + \frac{2}{r} \frac{\partial u}{\partial r} \right)$$...
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### Uniform Plane Question [closed]

Question: Communicating with submarines is very challenging due to the fact that seawater is a conductor (conductivity of roughly 5 S/m). This conductivity indicates that electromagnetic waves do not ...
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### Pulsed plane wave

My question is specifically concerned with ultrashort pulses: can a plane wave (one with infinite spatial extension) have a finite duration in time? Is there some physical principle that is violated ...
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### How can pressure and velocity fluctuations in acoustic plane waves be in phase and still hold to the B.C. that velocity must be zero at a solid wall?

In linear plane-wave acoustics (no mean flow, small perturbations, etc.), it is often derived that the phase of a traveling pressure fluctuation wave and a fluctuation velocity wave are the same. For ...
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### Poyting theorem for a plane wave

I would like to apply and verify the Poynting theorem for a uniform plane wave but there is obviously something wrong in my demonstration. The Poynting theorem expresses the conservation of energy: ...
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### Electric field operator in 2D geomatry

In the free field (3D), transverse electric field operator is given by the below expression; e^{\bot}(\textbf{R}) =i \sum_{\textbf{p},\lambda}\Big( \frac{\hbar cp}{2V\epsilon_{0}}\Big)^{1/2} \{e^{(\...
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### Plane wave conditions

Which conditions have to be fulfilled in order to approximate a light beam by a plane wave (i.e. $\phi(x)\approx \phi(0)e^{ikx}$)? I am looking for both mathematical and experimental conditions. At ...
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### Understanding wave packets, in particular matter waves, dispersion and point particles

Here is what I have gathered so far: Particles like an electron (i.e. with rest mass) can be represented as matter waves (deBroglie). The matter wave of a particle can be modelled a wave packet. A ...
### Importance of the $\exp (i \bar{k} \cdot \bar{r})$ part of the plane wave equation
I am having trouble grasping how the equation $\bar{E} \left( \bar{r}, t \right) = \bar{E}_{0} \exp \left[ i \left( \bar{k} \cdot \bar{r} - \omega t \right) \right]$ fully describes a plane wave. ...