Wave Definition and 999 Threads

  1. Like Tony Stark

    Mixed states and total wave function for three-Fermion-systems

    I've already calculated the total spin of the system in the addition basis: ##\ket{1 \frac{3}{2} \frac{3}{2}}; \ket{1 \frac{3}{2} \frac{-3}{2}}; \ket{1 \frac{3}{2} \frac{1}{2}}; \ket{1 \frac{3}{2} \frac{-3}{2}}; \ket{0 \frac{1}{2} \frac{1}{2}}; \ket{0 \frac{1}{2} \frac{-1}{2}}; \ket{1...
  2. zb23

    A Momentum operator -- Why do we use the plane wave solution?

    Why in order to derive the QM momentum operator we use the plane wave solution. Why later on in field theory and particle physics, the plane wave ansatz is so physically important?
  3. Philip551

    How can the direction of propagation help in determining the phase of a wave?

    Using the equation above I know that I have to find parameters k ##\omega## and ##\phi##. $$k = \frac{2\pi}{\lambda}$$ and $$\omega = 2\pi f$$ The problem I've been having is how you would go about finding ##\phi## since by solving: $$y(0,0)=0 \rightarrow sin(\phi)=0 \rightarrow \phi = 0...
  4. BiGyElLoWhAt

    3d plot of interference from 2 wave sources with 2d grid surface

    Desired output similar to image, but without the objects and with better wave interference: I tried plugging the following into wolfram (I specifically want the values to be adjustable): plot z= H*e^(-m*sqrt((x-a)^2+(y-b)^2))*sin(k*(x-a)+k*(y-b) -w*t) +...
  5. D

    Misc. DIY 'ECG' Machine: Testing Feasibility of Wave Transference

    I'm trying to make a DIY 'ECG' machine, except that it'll only record heartbeats on a piece of paper. Basically the piece of paper will be wound round a cylinder like object, which will be being spun slowly by a motor. A pencil at the end of a stick or something will be writing to this piece of...
  6. A

    Conservation of power in a traveling wave on a string

    The statement of the problem is: Consider a taut string that has a mass per unit length ##\mu_1## carrying transverse wave pulses of the form ##y = f(x - v_1 t)## that are incident upon a point P where the string connects to a second string with mass per unit length ##\mu_2##. Derive $$1 = r^2...
  7. Darmstadtium

    I Relationship between the Different Frequency vs Decibel Graph Peaks

    In the popular answer for the coin-mass question of Physics Stack Exchange, I am wondering what are the correlation between the first red peak at around 9kHz and the second red peak at 16kHz. I first thought that they are consecutive harmonics but there was no way of proving it as I do not know...
  8. Leureka

    I How does EM wave geometrical attenuation affect atomic absorption?

    Let's say we have a point source of an EM wave in a vacuum of total energy E, and an absorber atom at some distance from this source, whose first excited state is at the energy B, with B < or = E. The energy of the wave is constant as a whole, but at each point around the source the energy...
  9. homeworkhelpls

    How is Wave Intensity Affected by Half Amplitude and Double Frequency?

    TL;DR Summary: How do i find the intensity of this wave? I know I is proportional to amplitude / frequency squared, but I don't know what equation this comes from. And I don't know how to answer this.
  10. J

    Calculating Wave Amplitude & Wavelength in Water Pools

    How would we model/calculate the circular waves in a pool of water (wavelength and amplitude) from a mass falling into it from a given height, and from a fountain of water falling into it continuously? Is there is a way to describe the initial configuration of the wave based on the stimulus...
  11. uxioq99

    Time Independence of the Momentum Uncertainty for a Free Particle Wave

    Mine is a simple question, so I shall keep development at a minimum. If a particle is moving in the absence of a potential (##V(x) = 0##), then ##\frac{\langle\hat p \rangle}{dt} = \langle -\frac{\partial V}{\partial x}\rangle=0## will require that the momentum expectation value remains...
  12. M

    Showing that this equation is a solution to the linear wave equation

    For this problem, Where equation 16.27 is the wave equation. The solution is I don't understand how they got the second partial derivative of ##y## with respect to ##x## circled in red. I thought it would be ##1## since ##v## and ##t## are constants Many thanks!
  13. M

    Graph for sinusoidal wave travelling to the left

    For part(a) of this problem, The solution is, I don't understand why they assume on the graph where that the waveform is during it's phase. For example, could it not also be correctly drawn as shown in red: Could it not? Many thanks!
  14. I

    I Approach to extrapolate a "superpositioned" wave?

    Hello everyone, sorry if this is the wrong section. In this forum I'm a fish out of the bowl, my knowledge of physics is ages beyond most of the people on there, so please forgive my naivness. So, here's my problem, I'm a sort of "audio" engineer (won't enter much on detail) and on my free...
  15. J

    Trying to analyze a half wave rectifier with inductor and DC source

    I am trying to analyze a half wave rectifier with an inductor and DC source load. I understand the circuit but I guess I do not get the math. I am reading a book and this is the circuit and equations they came up with. I understand how they got from the first equation to the second equation but...
  16. Astronuc

    NASA NASA - Bimodal NTP/NEP with a Wave Rotor Topping Cycle

    New Class of Bimodal NTP/NEP with a Wave Rotor Topping Cycle Enabling Fast Transit to Mars https://www.nasa.gov/directorates/spacetech/niac/2023/New_Class_of_Bimodal/ Ryan Gosse, University of Florida, Gainesville, FL...
  17. Spinnor

    I Let a standing wave of length L go, get traveling wave of length 2L?

    Consider a very long string between fixed supports of mass density rho and tension T. At a distance 1 meter from one support pinch the string. The pinching does not change the tension. Adjust the mass density or tension so that when we add energy to this section of string we produce the first...
  18. maxelcat

    Standing wave, phase and antiphase

    I think I understand that points P and R are pi radians out of phase - reaching their max/min at the same time. But are P and Q in anti phase? What is antiphase exactly - is it when they are 180deg out of phase - or is it when they are anything other than totally in phase? I seem to find...
  19. loversphisics

    I Proving Behavior of Particle in Infinite Potential: Wave Function?

    Hello, guys! I have a question. How can I prove the behavior of a particle subjected to an infinite potential? Will the wave function exist?
  20. M

    I Can the Transverse Nature of a Wave from an Electron Gun be Observed?

    Hi. What equipment /mechanism / experimental procedure is used to determine that the nature of a wave fired from an electron gun is transverse in transit? Thanks Martyn
  21. M

    Deriving Wave Function for One-Dimensional Sinusoidal Wave

    Where did they get the equation in circled in red from? It does not seem that it can be derived from the graph below. Many thanks
  22. L

    B Quantum field theory and wave particle duality

    I recently watched this lecture "Quantum Fields: The Real Building Blocks of the Universe" by David Tong where the professor provides a succinct explanation of QFT in about 6 minutes around the midway mark. The main point being that there are fields for particles and fields for forces and the...
  23. N

    Average value of components of angular momentum for a wave packet

    I have typed up the main problem in latex (see photo below) It seems all such integrals evaluates to 0, but that is apparantly unreasonable for in classical mechanics such a free particle is with nonzero angular momentum with respect to y axis.
  24. Kyuubi

    Current on Infinite Periodic LC Circuit

    I wrote down the equation of motion for In(t) and I'm trying to match it with infinite spring mass system equation solution. In the spring mass system, we consider A to be the equilibrium length of the springs, and we can thus write Xn(t) = X(nA,t) and put it back into the equation of motion...
  25. H

    B Can we all agree "consciousness" is not required to collapse wave function?

    I see this written or talked about so often. Pop-sci for sure. But, whatever the wave function is, and whatever might collapse it, can we agree consciousness is not required to collapse it? I.E., the moon was there before "conscious" beings, on this planet or elsewhere, viewed it? Is at...
  26. H

    B Is there a resource that discusses wave collapse experiments?

    I would love to read about the different experiments that deal with the collapse of the wave functions and related items. Maybe summaries, I definitely don't want to get into math or anything. Just what causes it to collapse, what doesn't, can it partially collapse, can it collapse in these...
  27. H

    B Why does anyone think gravity might collapse wave function?

    Why on Earth does anyone, let along Roger Penrose, think gravity might be what causes the wave function to collapse? The most basic experiment in quantum physics, the double slit experiment, shows that collapse is most closely analogous to whether or not the item at issue (for example, an...
  28. M

    Why Wasn't (0,-3) Included in the Initial Graph of a Traveling Sinusoidal Wave?

    For part(a) of this problem, The solution is, However, why did they not have a point at (x,y) = (0, -3) initially? Also why did they not do a y against time graph?Many thanks!
  29. M

    Finding time difference between two arriving wave fronts

    For part(b), The solution is, However, where did they get the formula shown in red from? Many thanks!
  30. in2infinity

    B The wave solution to the Photoelectric effect

    I was recently examining the relationship between the work function of a material and its threshold wavelength. It was clear to me that the relationship is expressed as: (λW)² = c/2 Where λ is the threshold wavelength, W is the work function, and c is the speed of light. However, I am unable...
  31. K

    Can a Square Wave Tachometer Drive be Powered by a Sine Waveform?

    I'm a marine engine mechanic, and as engine controls & sensor systems have gotten more complicated with current technology, my shop gets more & more requests for instrumentation & control system repairs. I have a lot of trouble getting technical info from suppliers, so I have been starting to...
  32. M

    A Wave energy dissipated due to geometry

    Hey Condition 1: A 2D infinite plane and there is a circular hole in the middle. When t=0, an impulsive loading, P=f(t), is applied to the boundary of the circle(outward), so the wave will start at the boundary of the circle and propagate in the plane Condition 2: A 3D infinite plane and there...
  33. S

    Fourier transform of wave packet

    I am unsure if ##h(x,t)## really is a wave packet, but it looks like one, hence the title. Anyway, so I'd like to determine ##\hat{h}(k,t=0)##. My attempt so far is recognizing that, without the real part in the integral, i.e. ##g(x,t)=\frac{1}{2\pi}\int_{-\infty}^{\infty} a(k)e^{i(kx-\omega...
  34. H

    I Plane wave decomposition method in scalar optics

    Suppose an optical scalar wave traveling in Z direction. Using the diffraction theory of Fourier Optics, we can predict its new distribution after a distance Z. The core idea of Fourier Optics is to decompose a scalar wave into plane waves traveling in different directions. But this...
  35. H

    I Why is the electric field in y direction in a TE guided wave?

    Hi, I have a fairly simple question, but the answer is probably not as simple. I'm not sure to understand why in a guided wave (TE), the electric field is in the y direction. I know ##E_z = 0##, but why ##E_x = 0, B_y = 0##?
  36. N

    I Can I send an electromagnetic wave to a specific point?

    Since I'm computer engineer and don't have much experiences with electromagnetism, I'd like to know if it is possible to make an electromagnetic signal (250khz - 500khz) and send it to a point (with an error of maximum 1cm) in a room. If yes which devices do I need to setup my experiment?
  37. Shreya

    Phase of a wave - My interpretation

    Let's begin my interpretation: (please refer the image below). There I have considered a point in the disturbance/wave (let's call it ##P##),(not a particle of the medium) and I follow it as the wave progresses. The solid curve is a Pic of the wave at ##t=0## and the dotted one is its Pic at...
  38. H

    Energy conservation: electromagnetic wave in matter

    Hi, I completely failed this homework. I mean I think I know what happen, but I don't know how to show it mathematically. The energy lost by the wave is used to oscillate the electrons inside the conductor. Thus, the electrons acts like some damped driven oscillators. I guess I have to find...
  39. bobacity

    Wave Period Calculation: Is 0.1 the Correct Answer for Frequency of 1/10?

    I think the answer is just 1/10 (according to the formula for period), so the answer is 0.1. Is that correct? Thanks!
  40. bobacity

    Calculating Speed of a Wave | Solving Problem with Period of 0.025s

    Since the period is 0.025s, I think the frequency is 1/0.025s = 40 Hz. I don't know how can I proceed solving the problem from here. I'm assuming I will have to try to find the velocity and wavelength, but idk how.
  41. C

    B How is energy transferred from a wave to a photon?

    This is just a curiosity to me. My interest is from the position of a layman (as you will see from my description below). In the double slit experiment it shows a wave passing through both slits and interfering with itself to create an interference pattern. This is how I understand it... From...
  42. A

    Travelling wave and standing wave

    I wasn't sure about my solution for part c. I said "same distance as for traveling wave ie \lambda/2=0.06m". Also how do you enter LaTeX on this forum?
  43. S

    Correct statement about sound wave

    My answer is (1) and (2) but the teacher said it is only (1). I thought the speed of point at center of compression and center of rarefaction would be the maximum. Or the correct one is the speed at center of compression and center of rarefaction would be zero? Thanks
  44. H

    How is converted the energy of a E.M. wave in a conductor

    I'm thinking about how the energy is conserved when a E.M. wave pass through a conductor. If a E.M. pass through a conductor, the electrons must move "oscillated", thus the energy from the E.M. wave is converted to kinematic energy. Another way I see that is the E.M wave must generate a current...
  45. VVS2000

    I Wave packet experimental detection

    I know the wave function "collapses" when a measurement is made but still not satisfied with it
  46. S

    Correct statement about transverse wave propagating along a string

    My answer is (1) only but my teacher said (3) is also correct. I don't understand why, I think when the wave is moving to the left both Q and R will be moving upwards, no? Thanks
  47. Ahmed1029

    Sonometers, tuning forks, and wave periodicity

    Summary: Cofnusion regarding waves on a sonometer band A tuning fork is used to determine the wave frequency of a sonometer(according to my understanding), so whay about pulse waves? Does a pulse have a wave frequency? Couldn't a pulse travel over the sonometer band that can be determined by a...
  48. Ahmed1029

    I Wave number, frequency, and velocity in dispersive waves

    1) If I generate a dispersive wave, will it have well-defined constant wave number and frequency? Ones that don't change in time? 2) does the velocity of any point on the wave stay constant in time? 3) How does force interact with waves? Does a free wave act in analogy with free particles...
  49. yucheng

    I General solution of 1D vs 3D wave equations

    For the 1 dimensional wave equation, $$\frac{\partial^2 u}{\partial x ^2} - \frac{1}{c^2}\frac{\partial ^2 u }{\partial t^2} = 0$$ ##u## is of the form ##u(x \pm ct)## For the 3 dimensional wave equation however, $$\nabla ^2 u - \frac{1}{c^2}\frac{\partial ^2 u }{\partial t^2} = 0$$It appears...
  50. yucheng

    Why Is the Paraboloidal Wavefront Approximation Valid?

    We can either plot the real part of the complex amplitude, or the wavefront. However, how is wavefront meaningful for varying amplitude? In order to plot the paraboloid, we must vary ##z##, which varies the amplitude ##\frac{A_0}{z}##. Unless the amplitude is varies little, i.e. ##1/z##...
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