Electrodynamic Definition and 34 Threads

Hello everyone, I try to calculate brake force for primitive eddy current brake, but I have problem with determining the frequency (skin depth) and characteristic length (magnetic Reynolds number). I attach the equations and a scheme of the model.

Hey guys! I am currently tackling the following problem: An electric dipole P is kept close to a conducting grounded sphere of radius A -assume a distance B between the center of the sphere and dipole. What is the potential of the dipole outside of the sphere when the orientation of the dipole...

Can someone explain what exactly happens at (4) ? I do not clearly follow, except that there is some cosine law going on? I also do not really understand why at (3), r' doesnt have a z hat component, but I can live with that.

There is a well-known Abraham-Lorentz equation describing radiative friction. Suppose a particle moves in an electromagnetic field. ma(t)=q(E+vxB) + m(tau)a’(t) By solving this equation numerically, I get non-physical solutions(runaway solutions) Although, it would seem that an electron in an...

Let's say we have a circuit, and in that circuit there's a resistor, and there's a wire that goes around it so that the current can flow freely without getting to the resistor. my question is this: how does the current "knows" to flow towards the around the resistor? how does it know not to get...

Moon and Mars have no magnetic field, but that they are immersed into solar magnetic field. If I place a long wire along north pole, perpendicular to Sun, while Moon/Mars moves along its orbit, the wire cuts magnetic field lines; this should produce a difference of potential between fare edges...

What is the difference between electrodynamic suspension (EDS) in maglev trains and quantum levitation? I'm having trouble distinguishing the difference between both.

Homework Statement Consider a charged body of finite size, (\rho=0 outside a bounded region V). \vec{E} is the electric field produced by the body. Suppose \vec{E} \rightarrow 0 at infinity. Show that the total self-force is zero: \int_V \rho \vec{E} dV = \vec{0}, i.e. the charged body does not...

Homework Statement [/B] In a thin rectangular metallic strip a constant current I flows along the positive x-direction, as shown in the figure. The length, width and thickness of the strip are l,w and d, respectively. A uniform magnetic field B is applied on the strip along the positive...

First, sorry if something is not totally clear, I'm translating physics term the best I can! 1. Homework Statement A sphere or radius a of permittivity ε2 is placed in a dielectric ε1. Without the sphere, we would have E = E0. We want to find the solution to this problem when ε2 = 1...

I found two ways to solve this problem, but I get two different solutions, it's confusing because I can't see the flaw in wrong solution. 1. Homework Statement Long cylindrical inductor of diameter D1 and inductance L1 is connected to battery and creates magnetic field B1. Inductor is then...

If the magnetization vector is in the z direction, is the bound surface current of a cube always 0, since z cross z is 0, and x and -x cancels and y and -y cancels out?

Hello, I have a doubtaboutthe use of Gauss theorem in the presence of a coductor. If I have a infinite cylindric long shell with a charge density ƍ of radius b and inside of it a cylindrical conductor of radius a, also of infinite lenght, what will be the electric field in a point located...

A company called ClearSign says it can use electric fields to shape combustion flames to improve powerplant efficiency by upto 30%: http://www.technologyreview.com/news/520466/flame-shaping-electric-fields-could-make-power-plants-cleaner/...

I was reading about the electrodynamic tether experiments in low Earth orbits to generate electricity. I had a doubt regarding the mathematics that went behind calculating the emf across the tether. I read further and i realized they use the equation ε=Bvl, but the problem with this is that the...

Hey all. I am taking my second college physics course (electromagnetic physics) and am looking for some help deriving the equations. I found it very helpful to know how to derive many of the equations in my first physics course. So far we have studied e fields, guass's law, capacitors...

I have studied Jackson, Landau, and Barut textbooks on electrodynamics, together with Weinberg's Gravitation and Cosmology textbook, and I find that the usual action S = S_f + S_m + S_{mf} is inconsistent and not well-defined. For instance, what is the meaning of S_f? A free-field term? Or...

Here is a second thought experiment I designed to test if I understand certain concepts concerning electrostatics correctly. Help will be appreciated. There must be an error somewhere in the explanation below; I am giving the explanation as if “factual” only to explain how I understand it at...

I am casually working through Introduction to Electrodynamics, 3rd ed. by David J. Griffiths and created some theoretical situations to test my understanding of the subject matter. I am having difficulty with some, and will appreciate input. Consider the following theoretical cycle (see the...

Hey everyone, Just a quick question about a few electrodynamic concepts: 1) retarded time: t = t_r - (curly)r/c. Is t = total time, t_r = time elspased since the electromagnetic 'news' reached the point in question, and r/c = time taken to reach the point in question? 2) I'm a bit...

I am sort of having a brain fart about this, when sending electricity threw a metal it becomes negatively charged correct? |-------------------------------------------------< |-->(Positive)Power(Negative)-------->Metal-------^ The electrons leave the negative terminal, pass threw the...

Two very large parallel conducting plates of very large length l, and width w are separated by a distance d. A current I=Jw flows to the right in the lower plate and to the left in the upper plate. Each of the two currents produces a magnetic field \frac{B}{2} between the two plates. (a)...

Have anyone of you have listened about Melvin Schwartz's book on electrodynamic.https://www.amazon.com/dp/0486654931/?tag=pfamazon01-20. It is known to be inconventially written. Is this a good book for an undergrad. If not which book is better between David J. Griffiths and Purcell. Thank You.

Is there a simple way to understand why the Lagrangian of the classical electrodynamic field is (in SI units) E^2/2 e0 - B^2/2 mu0 ? Why is there a minus in it? Is there some simple, intuitive explanation for it? Heinz

In Edward Collet's book "Polarized Light: Fundamentals and Applications", Chapter 3 states that: However, in recent years (as recent as 2008), I came across a paper published in Nature Photonics that a group of scientists, Haifeng Wang et al. from Data Storage Institute based in Singapore...

Hello, I would like to know if there are experimental tests of the Equivalence Principle in the realm of electrodynamics. The book by http://books.google.com/books?id=BhnUITA7sDIC&pg=PP1&dq=Theory+and+Experiment+in+Gravitational+Physics&lr=#PPP1,M1" contains a lot of material about the...

In David Bohm's "Quantum Theory" (an intro topic building up to the Rayleigh-Jeans law), he states: "We now show that in empty space the choice div a = 0 also leads to \phi = 0 ... But since div a = 0, we obtain \nabla^2\phi = 0 This is, however, simply Laplace's equation. It is...

I would like anyone to reccomend good books on Electrodynamics. Any links to online resources for reading are also welcome.

Homework Statement Under what conditions is the quantity E^2+B^2 relativistically invariant? Homework Equations E\cdot B and E^2-c^2B^2 are invariant. (Also Lorentz transformation laws for E and B which I won't type here.) The Attempt at a Solution I think you can just...

I am new to physics. I am trying to build an electrodynamic trap using 2 ring electrodes to trap aerosol particles. I will be applying a voltage of 5 KV. What are the things that i need for example what camera do i use to visulaize the particles and what distance should i maintain between the rings

Most (or all) solvable EM problems are either (1) given a fixed static or periodically-varying EM field, find the motions of charged particles, OR (2) given a fixed static or periodically-varying charge distribution, find the resulting EM field. That is, either (1) solve the Lorentz force...

Can someone explain how to solve the following problem? A physical electric dipole consists of two equal and opposite charges (+/-)q separated by a distance d. Find the approximate potential at points far from the dipole.

hit a wall,u feel pain,what kind of forces r involved,r they electrodynamic?

Consider an electric field throughout the region of an electrodynamic system: E [x,y,z,t] The function, E [x,y,z,t], is a macrostate. Corrresponding to it are all the ways the charge in the system could be arranged ( p [x,y,z,t])so as to produce this macrostate. The set of p [x,y,z,t]s...