Interaction Definition and 653 Threads

Book: Classical mechanics (textbook) by Douglas Gregory (cambridge publications) Law of mutual interaction states that when two particle (let it be P1 and P2) interacts, the particle (P1) induces an instantaneous acceleration (a21) on particle P2 and the particle P2 induces an instantaneous...

Homework Statement Problem 7.15 from Aitchison and Hey, Volume I, 3rd Edition. Verify the forum (7.139) of the interaction Hamiltonian \mathcal{H_{S}^{'}}, in charged spin-0 electrodynamics. Equation 7.139 is \mathcal{H_{S}^{'}}= - \mathcal{L}_{int} - q^2 (A^0)^2 \phi^{\dagger} \phi...

Homework Statement The problem is stated on page 10 and it is number 9. http://panda.unm.edu/pandaweb/graduate/prelims/QM_F11.pdfHomework Equations I know how to write Sy in the z basis for either spin up or down and I have all the spinors.The Attempt at a Solution I tried solving for |ψ(t)> by...

Hi, I've been thinking about the following scheme: let's say I have an incoming photon ray with wavefunction ψ1 that finds a bloch electron with wavefunction ψ2. Is there any way to compute the optical coefficients (transmitivity, reflectivity etc) of the material knowing only this two ψ and...

Hello All, I am quiet new to the subject, so if anybody can help me. The four fundamental forces of nature, gravity, strong, weak,electromagnetism. Through weak force, all the electrons, protons and neutrons interact with each other. An attempt was made late in the 20th.century to unify...

Dear all respected expert/collegues, I'm setting out a photoelectrochemical cell. I'm facing problem to regulate temperature in my photoreactor durng reaction. Can i just dip the photoreactor inside a big water jacket? But i wondering incoming photon or light supplied by my Xenon arc lamp...

(I am not sure what is the best subforum for this doubt, please move the thread if necessary) When we study the interaction of the electromagnetic waves with a charged particle (let's say an electron) we can find two totally different approaches in the literature. If we are talking about light...

Hi all, If I take an action involving two point particles coupled together by a delta function contact interaction is it possible to carry out the variation with respect to the fields? For e.g. S = \int dt \frac{1}{2} \dot{x}^{2} + \int \int dt \dot{x}(t) \delta^{D}\left(x(t) - y(t')\right)...

Let say I want to study electron-proton scattering (without considering proton's quarks, i.e. no QCD), which is the Lagrangian? I've seen two different answers to this question :confused: First one: L=\bar{ψ}e(i∂-me)ψe+\bar{ψ}p(i∂-mp)ψp-\frac{1}{4}Fμ\nuFμ\nu-e\bar{ψ}eγμψeAμ+e\bar{ψ}pγμψpAμ...

I wanted to know if there is a mathematical model to know the force with which a source of a magnetic field attracts or repels another source of magnetic field. For example, the mathematical model for the electrostatic force a charged particle exerts over another charged particle is: F =...

Hi, i have been trying to figure how to solve this problem, i just don't know how to proceed Homework Statement A particle with spin s=1 has due to rotational invariance all three states |s_z\rangle=1, |s_z\rangle=0 and |s_z\rangle=-1 degenated with energy E_0>0. Then its introduced an...

I am trying to run a simulation (transient analysis) in ANSYS Workbench of a rolling tire on a flexible pavement surface. The tire is a truck tire with pressure of 0.7 MPa. I defined various outputs at consequential small time steps, and I can see the tire gradually inflating until (what...

Homework Statement A particle with known rest mass energy, m_{p} c^{2} pass through a cloud of monoenergetic photons with energy E_{\gamma}. The particle collides with a photon and a particle A, with mass m_A is created. Show that the minimum energy of the particle required for the interaction...

I'm currently reading about the parton model and deep inelastic scattering. As I've understood it was observed that when protons collided at high energy very little transverse momentum transfer was observed, while when electrons were collided with protons transverse momentum transfer was...

Homework Statement Homework Equations This one has confused me, I know that Baryon number has to be conserved so X has to be a baryon. I can see how charge is conserved The Attempt at a Solution I know this is the strong interaction. Is it a collision? Is that where the...

I was reading about how a plane mirror reflects light and would like confirmation I have the right theory. It says that the metal coating of a mirror is a conductor in electrostatic equilibrium which means the electric field is zero. As the electromagnetic wave hits the mirror the electrons...

Hi All, I am trying to understand why Cooper pairs form. The textbook proof that I am reading (Grosso & Parravicini) starts out as follows: Imagine a 'passive' electron gas filled out to some Fermi sphere kF. Add two 'extra' electrons that interact via a potential U(x-x'). Transform to...

Hello, I was wondering if there is any evidence on how (free/not within nucleus) neutron/neutron interactions work. I know there is QCD which states they attract (but maybe only in a nucleus?), but that's theory - has this been experimentally proven at all ? I'm only interested in the free...

The usual story is that after a solar flair (coronal mass ejection) towards the Earth the Earth's magnetic field gets strongly deformed. It usually takes a few days from the solar event to when the Earth is impacted. But I wonder if there is also a direct interaction: If there is drastic...

Before I sound stupid I am only at GCSE level (high school in America) so understanding is little. But theoretically could an alpha particle (helium nucleus) gain electrons and become a helium atom. If this is possible can it be done with two beta particles? Correct me I in wrong an explain why...

I've attached a video of magnetic putty swallowing a rare Earth magnet. Will the resulting shape of the putty be cubed like the rare Earth magnet (equal distribution of magnetic forces along the surface) or will the shape be spherical (weird magnetic forces along the edges of the cube)...

In the well known Ising model, without any external field (H=0), the energy (E), spins (s) and exchange interaction (J) are related as in the following equation $$ E = -\sum_{<ij>}J_{ij}s_{i}s_{j} $$ Jij is site dependent and consists of three components JAA, JBB and JABwhere A is say up...

Hello if i have two waves soliton y=A \sech^2 (k(x \pm ct)), both solution of KdV differential equation how i find a equation for the interaction between the right and left waves \pm c i think on supperposition waves, y=A \sech^2 (k(x + ct))+B \sech^2 (k(x - ct)), but i don't understand if...

The interaction of light with matter, or EM waves in general, falls into 3 categories: transparent where they pass through, opaque where they are scattered, and shiny where they are reflected. What on the quantum mechanical level about the atoms electrons determines those properties? I think the...

Homework Statement See attachment Homework Equations The Attempt at a Solution Thus far I believe I am supposed to use calculate the interaction with kQq/Δr? I have tried summing over interactions so that 1/4∏ε*[(-Q)(-q)/(r-d/2+D/2) + (-Q)(q)/(r+d/2+D/2) + (Q)(-q)/(r-d/2-D/2) +...

I am simulating protons and electrons in a simulator that runs 1 femto seconds per second up to 1 second per second. So it can accurately show the passage of charge particles through space with data being updated on their displacement, velocity and acceleration. However I am now adding in...

Hello :)I was working on a project for one of my classes, and it had to do with electromagnets + magnet's B field interactions(A simple demonstration of a few laws of electromagnetism). Basically its a simple configuration like this random photo I found...

Consider the S-matrix: <f|U(t,-t)|i> When going into the interaction picture, this becomes: <f_I|U_I(t,-t)|i_I> where the propagator is the interaction picture propagator, and the states are interaction states. Can you say that: <f_I|U_I(t,-t)|i_I>= <f|U_I(t,-t)|i> ? It...

S-Matrix is calculated in that the interaction at infinite past and future time is zero.Then how can we solve the problem of ''scattering'' where the interaction presents at all time(e.g considering interaction of electron in an atom) with QFT?

Homework Statement Object A of mass 10 kg moving at 10 m/s [E] interacts with (but does not touch) Object B of mass 8 kg moving at 12 m/s [N]. What is the minimum possible kinetic energy of the system after the collision? Homework Equations M1V1o + M2V2o = M1V1f + M2V2f KE = (.5)(m)(v2)...

Let's consider a mach-zehnder apparatus The picture is below: http://en.wikipedia.org/wiki/File:Mach-zender-interferometer.png 1. When the photon encounters (and emerges from) a half-silvered mirror does it loose any energy? The photon does change phase when it moves through a half...

Hi, I just started self studying solid state and I'm having trouble figuring out what the hamiltonian for a square lattice would be when considering the Heisenberg interaction. I reformulated the dot product into 1/2( Si+Si+δ+ +Si+δ+S-- ) + SizSi+δz and use Siz = S-ai+ai Si+ =...

Two permanent magnets are on the table some distance apart and having some arbitrary orientation relative to each other. When we let go of them they will rotate and translate until they stick together. I am looking for suitable equations to model this interaction on a computer. Also, if anyone...

Okay, I am not an electrical engineer but I dabble with circuits, electronics, and electromagnets. Id like to know if it is possible to measure the voltage, or current (not sure sure which is applicable here) using the measurement of interaction between one small magnetic field produced, and...

I know that the generators of the Poncaire group that are associated with *orbital* angular momentum belong to an infinite dimensional representation, i.e. \begin{equation} L = \frac{\partial}{\partial \theta} \end{equation} Also the spin generators are associated with some finite...

I'm just wondering... Regarding the single & double slit experiments... Why does every interpretation say that the photographic screen is 'measuring' the position of the particle traveling towards it? Why not say that the photographic screen interacts with an electron that is spread out...

hello! I want to know which factors determine the strength of interactions between two atoms (which both or one or none can be a part of a bigger molecule) thanks

The strong interaction has color ''charge'',the electromagnetic interaction has electric charge,the gravity interaction has mass ''charge'',then what is the charge in weak interaction? Each interaction corresponds to a symmetry.Symmetry SU(3) for strong interaction, SU(2)xU(1) for...

Question on Molecular Orbital Theory (and the "dot" that represents no interaction) I have a question about the "dot" that represents no interaction between orbitals. For example, in the molecular orbitals of H3, there is the lowest energy molecular orbital that has two bonding interactions...

hello! which equation descripts the electrostatic interaction between two non-point (ie. that have dimensions) charged particles? thanks!

I can't find sth about self interaction which tells for sure in what situations we should consider it and how to manipulate it! Can we talk about self interaction for e.g. a single electric charge?Or it appears only in certain cases?How should we calculate it? Thanks

How does light cause matter to move? For example, when a photon collides with an atom, an electron absorbs the photon and moves to a higher energy state. If the energy is not used then the electron falls back to a lower energy state and emits radiation. I am unsure of how the photon in the above...

Ok so I was wondering, let's say I have a device (eg., shaped like a toothpaste box with the two square ends cut off). I make 2 of the opposite faces from copper plate and the other 2 from iron plate (for example). I then generate an electric field in the box with the copper plates, and a...

hello! which factors determine, which parameters affect, the strength of an atomic interaction or bond? thanks!

For my understanding of electron-phonon interaction is that when electron moves across a lattice, it distorts charges and it leads to a higher density of positive charge at an instance of a second. As the electron leaves the region of high positive charge, another electron will jump into...

Let's suppose, we have two ideal point charges q_{1}, m_{1} and q_{2}, m_{2}. One of them comes from almost infinite distance with relative velocity v_{0}, w.r.t another charge. I'm curious how can we analyze this situation mathematically, i.e the equations of the motions of these particles...

Hi, there are two material points with unitary mass that can move on a stright line. They are subject to a potential of mutual interaction V which depends on x and y and it's not symmetric, where x and y are the coordinates of the two points. I can choose in the istant 0 v1,v2,x and y. How...

Roger Penrose in Chapter 25 of his book The Road to Reality describes a "zigzag" model of the electron that consists of a pair of massless components one with a left-handed spin (the zig) and the other with a right-handed spin (the zag). He says that the Dirac equation can be written as a pair...

Recently, I was surfing Youtube looking for scientific videos, and I came across one on black holes. Naturally, I figured I'd already heard it all before, but decided i might as well watch it anyways. At one point, it talked about black holes making "dents" in space-time due to its its gigantic...

Is the wave function, an unreal (but a useful mathematical) tool, to partially model a real interaction? i.e. can probabilities have an existence of their own? i.e. exist by themselves without referring to some underlying phenomena? The wave function is a mathematical/probability tool. It is...