Wave Definition and 999 Threads

I never took any physics courses nor don't have a background in mathematics never the less I became very interested in quantum physics after reading Sean Carroll's book Something deeply hidden. One of the difficult things for me to wrap my head around was the concept of superposition and...

Is there a standard mathematical definition for "wave"? What is the definition? Assuming that there is a definition, what are the mathematical definitions of the properties of waves? For example, how is the "group" of a wave defined? ( as in the "group" that has a "group velocity"). I'm not...

I was conducting an experiment with a tone generator (330 Hz) in boxes of different sizes with a glass plate placed on top of the box. There is a receiver about .55 meters away. Without any interference, the receiver registered -41 db +/- 1 db. When the tone generator is placed in the box and...

In the blast wave generated by an explosion, after a first violent increase in the air pressure, there is a "negative phase" in which the pressure drops below the initial atmospheric pressure (see e.g. https://en.wikipedia.org/wiki/Blast_wave ). According to wikipedia, this underpressure is the...

I have heard that if you could make a sheet of material thinner than a wavelength representing a particle and fire particles at it, that particle might be detected on the other side of the sheet material when you try and detect it due to Quantum Tunneling i believe. Does that mean that it's...

My neighbor has two AC condensers are driving me insane. I took measurements of the units, and they were between 33.5db - 47.9db at 80HZ. About 3 feet away is a cinderblock privacy fence between us. It is about 10 feet tall. His home is on an elevation about 4 feet higher than mine (so the...

Hi, I was reading about the Pilot Wave theory. I also found this vid: Is the Pilot Wave theory against most of the other interpretations of QM? And what are the main things one needs to accept? - In pilot wave theory, --- we have to accept a medium of unknown particles. ---...

Hi, I am very new to this, but I can't help to ask the question to which I cannot find the answer on google. Was the process of investigating of wave collapse - split into sections - to identify which section produces the collapse? I am a web programmer and sometimes this is a method I employ...

I have a basic question in elementary quantum mechanics: Consider the Hamiltonian $$H = -\frac{\hbar^2}{2m}\partial^2_x - V_0 \delta(x),$$ where ##\delta(x)## is the Dirac function. The eigen wave functions can have an odd or even parity under inversion. Amongst the even-parity wave functions...

Hi, I've been reading Brillouin's 'Wave Propagation in Periodic Media'. About the following equation $$\nabla^2u_1+\frac{\omega^2_0}{V_0}u_1 = R(r)$$ Brillouin states that "it is well known that such an equation possesses a finite solution only if the right-hand term is orthogonal to all...

I don't see why it is not ##P(\omega)\propto |\langle \psi | \mathbb{P}_{\omega}|\psi\rangle |^2.## After all, the wavefunction ends up collapsing from ##|\psi\rangle## to ##\mathbb{P}_{\omega}|\psi\rangle.##

The energy density of an EM wave is given as (1/2) ϵ E^2 + (1/(2μ)) B^2. This is derived from the energy density of the electric and magnetic fields of capacitors and inductors, respectively. But why should the energy density of the fields of capacitors and inductors be the same as that of...

I want to find the particular solution to the differential equation$$g(L-x) \frac{\partial^2 y}{\partial x^2} = \frac{\partial^2 y}{\partial t^2}$$with the boundary condition ##y(0) = 0## for all ##t##. If the coefficient of ##\frac{\partial^2 y}{\partial x^2}## were constant then it could be...

When wave function collapses how long is it collasped... Shooting electrons at a double slit and observing the electrons before they reach the 2 slits collasped the wave function...so is its behavior particle like forever? Quantum mechanics is simple however wrapping ones head around it is...

light is electromagnetic wave ,so does it also have magnetic and electric field,like all others waves(micro,gama,xray,radio waves etc..)? i never heard that some one talk about light in sense of magnetic and electric field.. if it has ,why than compass don't response to light?

Let me ask a very primitive question. To and fro motion of pendulum under gravity tells us potential energy + kinetic energy = const. At the top points potential energy: max kinetic energy :0 At the bottom point potential energy: 0 kinetic energy :max EM wave is usually illustrated as...

we know that all emission from asctrophysical context is doppler shifted. So, how to make sure the doppler shifted 21 cm not contaminated by some other emission?

Hello! I recently had a discussion with a person who's well-read on quantum physics and I was suprised by his claim that "light is in no sense regarded as a wave" in quantum mechanics. His support for this claim was that there are no wave crest or wave trough, there is nothing moving. What...

Hello! I have been recently studying Quantum mechanics alone and I've just got this question. If the potential function V(x) is an even function, then the time-independent wave function can always be taken to be either even or odd. However, I found one case that this theorem is not applied...

I've marked the right answers. They mainly indicate at power carried by the particles being zero, and here is my doubt- why should it be zero? Shouldn't it have some definite value? I do understand that the kinetic energy is max at the y=0 and potential energy is max at y=A, but I don't know...

To begin with, I am trying to understand how does ##E^2 (x,t)## transform to ##A_y^2 + A_z^2##. And, noting that the already established equation of ##E^2 = E_y^2 + E_z^2##, I would assume that ##E^2 (x,t)## somehow ends up to being ##A_y^2 + A_z^2##. However, noting that ##E^2 = (A_y...

This is not a homework question, it is for my understanding so please do not answer this question with a question. I have found this great animated gif but it appears to be for a fixed end (notice wave inversions at the end). Has anyone seen a similar one for a free end? Many Thanks

Summary:: A plane wave incident upon a planar surface - determining polarization, angle of incidence etc. 𝐄̃i = 𝐲̂20𝑒−𝑗(3𝑥+4𝑧) [V. m−1 ] is incident upon the planar surface of a dielectric material, with εr = 4, occupying the halfspace z ≥ 0. a) What is the polarisation of the incident wave...

The problem I am having is "What can you conclude about wave prorogation in SR given the results?". The best I can come up with is that the number of wave planes N crossing a section of spacetime in either frame is the same. The section may be bigger or smaller depending on which frame you're in...

Hey I am trying to learn how waves move in time and I am not sure how to solve the following question. Can someone please guide me through it.

I am solving the wave equation in z,t with separation of variables. As I understand it, Z(z) = acos(kz) + bsin(kz) is a complete solution for the z part. Likewise T(t) = ccos(ω t) + dsin(ωt) forms a complete solution for the t part. So what exactly is ZT = [acos(kz) + bsin(kz)][ccos(ωt) +...

Hello everybody, I have to find the amplitudes of a wave that goes through 4 different mediums in terms of ##E_0##, suffering reflection in the first three but not the last one. I calculated the corresponding reflection indexes of the three mediums (all of them real). Following calculations, I...

I want to split a fat laser beam and interfere it with itself, kind of like this: The very obvious problem is that the wave peaks shown as black lines would be a whole lot closer together, so the interference fringes would be sub-microscopic. If a couple of glass wedges - oddly-shaped prisms...

Does each point in a stationary wave change its displacement and hence it's amplitude? If yes, why is this so? However, why does the amplitude at the node and antinode remains zero and maximum respectively? Does the above have to do with the fact that all the formation of a stationary wave is...

To begin with, I can first let ##T(x,y) = X(x) Y(y)## to be the given solution. With this, I can then continue by writing: $$Y \frac{\partial^2 X}{\partial x^2} + X \frac{\partial^2 Y}{\partial y^2} = 0$$ $$\Longrightarrow \frac{1}{X} \frac{\partial ^2 X}{\partial x^2} + \frac{1}{Y}...

hello , hope all of you are doing well , i have question about the unit of the function of waves of string fixed in both boundary , the function of waves is function of two variables x and t , so it's function describe the displacement in function of place and time , Ψ(x,t)=φ(x)*sin(ωt+α)...

Hello all, I am a newcomer here. Not a physicist, just an enthusiast. ;) I was thinking whether it is possible to separate a one-particle wave function into two, "completely disjoint" parts. The following thought experiment explains better what I am thinking about. Let us suppose, that there...

Hi there! This is my first post here - glad to be involved with what seems like a great community! I'm trying to understand the acoustics of a finite plane-wave tube terminated by arbitrary impedances at both ends. So far all of the treatments I've managed seem only to address a different...

The book's procedure for the "shooting method" The point of this program is to compute a wave function and to try and home in on the ground eigenvalue energy, which i should expect pi^2 / 8 = 1.2337... This is my program (written in python) import matplotlib.pyplot as plt import numpy as...

How do I get the wave dispersion for a 2D continuum unit cell subjected to a periodic boundary which is excited longitudinally? I'll be applying forces in ABAQUS with varying frequencies. I have come across Blochs theorem but I can't find any application of it in continuous systems. Every...

Applying the time reversal operator to the plane wave equation: Ψ = exp [i (kx - Et)] T[Ψ ] = T{exp [i (kx - Et)]} = exp [i (kx + Et)] This looks straightforward as I have simply applied the 'relevant equation' however my doubt is in relation to the possible action of operator T on the i...

Some questions: Why is this even a valid wave function? I thought that a wave function had to approach zero as x goes to +/- infinity in all of space. Unless all of space just means the bounds of the square well. Since we have no complex components. I am guessing that the ##\psi *=\psi##. If...

I was thinking about a problem I had considered a long time ago in some thread, finding an example of a wave function ##\displaystyle \psi (x) =e^{iax}\phi (x)## with ##\displaystyle\phi (x)## being periodic with period ##\displaystyle L## and the corresponding Schrödinger equation...

First, I have a question about supereposition of the plane waves - whether the direction of all such plane wave is same, i.e. ##\vec{n}## is in some direction. If not, I think it would be ##\vec{E}(\vec{x}, t)=\int\mathbf{\mathfrak{E}}(\vec{k}')e^{i\vec{k}'\cdot\vec{x}-i\omega t}d^3k##. Besides...

Hi, I was trying to get some practice with the wave equation and am struggling to solve the problem below. I am unsure of how to proceed in this situation. My attempt: So we are told that the string is held at rest, so we only need to think about the displacement conditions for the wave...

To plot ##u(r)## we need to find the solutions for each region. Which is in the relevant equations part. Now, I have to do this numerically. Using python 3.7 I made an ##u## which is filled with zeros and a for loop with if/elseif statement, basically telling it to plot values for whenever...

Hi, I just need someone to check over my work. I am having trouble with the next part of this question and I just wanted to check that this part was correct first. I have two particles in an infinite square well (walls at x=0 and x=L). I need write an expression for the spatial wave...

So to do this problem I need the relevant formula for phase difference which is this: I first need to find wavelength and this is lambda = velocity/frequency So lambda = 257/641 = 0.40093603744 m Hence phase difference (in radians) = 2pi * (2/0.40093603744) = 31.3 rads My concern is that...

There is a multiple choices question about traveling wave in my book. Based on the graphic, if T = 2s, the wave equation is ... My answer : ω = 2π/T = 2π/2 = π k = 2π/λ = 2π/4 = 0,5π → in my country, we use comma (,) for point (.) y = ±A sin (ωt - kx) y = -0,5 sin (πt - 0,5πx) y = -0,5 sin...

Hi all. I just watched a great video on gravity wave 'telescopes'. So i have been wondering if any of my intuitive hunches are right about gravity waves. Accelerated masses generate gravity waves that dissipate energy.. So let's say i turn my rocket ship engine on while sitting in deep...

Hi, So the main question is: How to deal with power loss in E-M waves numerically when we are given power loss in dB's? The context is that we are dealing with the damped wave equation: \nabla ^ 2 \vec E = \mu \sigma \frac{\partial \vec E}{\partial t} + \mu \epsilon \frac{\partial ^ 2 \vec...

Since the membrane doesn't break, the wave is continuous at ##x=0## such that ##\psi_{-}(0,y,t) = \psi_{+}(0,y,t)## ##A e^{i(k \cos(\theta)x + k \sin(\theta)y - \omega t)} = A e^{i(k' \sin(\theta ') y- \omega t)}## Which is only true when ## k' \sin(\theta ') = k \sin(\theta) ##. From the...

I've searched threads and can't find easy explanation - sorry if I'm missing something basic / have a basic understanding error! In the classic picture of an EM wave with the Electric and Magnetic components oscillating at 90 degrees to each other, both components cross the middle axis at the...

Frequency nU = W/2pi = 287.6/6.28 = 45.796 = 45.80 Speed C = nU * I = 45.80 * 186.9 = 8560 m/s

I am not sure what is meant by "equation of propagation of crest" but this is my attempt: First, I find the velocity of wave: v = ω / k = 0.5 / 0.25 = 2 m/s Then I calculate wavelength: k = 2π / λ λ = 4 m I imagine the crests will move to the right along with the wave so I try to use equation...