Aug 13 2019

might suggest that the retarded scalar potential for a moving point charge is {also } .. Thus, we have obtained the so-called Liénard-Wiechert retarded potentials. Lecture 27 – Liénard-Wiechert potentials and fields – following derivations in. Lecture When we previously considered solutions to the. The Lienard-Wiechert potentials are classical equations that allow you to compute the fields due to a moving point charge in the Lorenz Gauge Condition.

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Part of a series of articles about Electromagnetism Electricity Magnetism Electrostatics. Sign up using Facebook. My thesis briefly discusses aspects of Whitney’s argument and cites many relevant wiechrrt for further study.

There is 1 pending change pktential review. The argument proceeds in two steps: Art Brown 4, 1 18 It is important to take into account the zero point field discovered by Planck M. Home Questions Tags Users Unanswered. When you say “it is clear that if the charge cloud was small enough, or if we were far enough, the potential would be just the potential for a point charge of charge equal to the total charge eiechert the cloud” you’ve also implicitly made the assumption that the charge is moving slowly enough that it’s distribution may be integrated over at a single time co-ordinate.

I don’t think the increase in potential due to the moving charge leading to an “overcounting” Wieechert in disagreement with Feynman’s result. Post Your Answer Discard By clicking “Post Your Answer”, you acknowledge that you have read our updated terms of serviceprivacy policy and cookie policyand that your wirchert use of the website is subject to these policies.

To compute energy, it is necessary to use the absolute fields which includes the zero point field; otherwise, an error appears, for instance in photon counting. Jackson refutes Chubykalo’s argument by claiming that Lienard-Wiechert potentials are indeed a solution of Maxwell’s equations, but Chubykalo did not state the issue as precisely as Whitney, which is related to boundary conditions rather than solutions to the differential equations.


Schwarzschild and Fokker lienarv the advanced field of a system of moving charges, and the retarded field of a system of charges liwnard the same geometry and opposite charges. A similar argument is used by Schwartz in his “Principles of Electro-Dynamics”. So why is my argument wrong?

Electrodynamics/Lienard-Wiechert Potentials

This earlier potentiql in which an event happens such that a particle at location r ‘sees’ this event at a later time t is called the retarded timet r. Lamb’s correction of levels of H atom. I like it, except this bit:.

What matters is if it gives a correct solution to Maxwell’s equations and Feynman’s derivation does. It seems to me that it is this extra counting which makes the potential to be larger than expected, and I am uncomfortable with it.

The first term describes near field effects from the charge, and its direction in space is updated with a term that corrects for any constant-velocity motion of the charge on its distant static field, so that the distant static field appears at distance from the charge, with wiechdrt aberration potntial light or light-time correction. Quantum electrodynamics helped bring together the radiative behavior with the quantum constraints.

I think I need more time than I’ve got right now, to avoid making another goof.

Thus, electromagnetic radiation described by the second term always appears to come from the direction of the position of the emitting charge at the retarded time. I won’t try to defend Feynman’s derivation, which seems strangely non-relativistic. The electric and magnetic fields are in non-covariant form:.

By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. I like it, except this bit: You’re not the only one who’s noticed this double counting: However, under certain conditions, there always exists a retarded time.


Physics Stack Exchange works best with JavaScript enabled. Electromagnetic tensor stress—energy tensor. We can calculate the electric and magnetic fields directly from the wiechrrt using the definitions:.

Multiplying electric parameters of both problems by arbitrary real constants produces a coherent interaction of light with matter which generalizes Einstein’s theory A.

Liénard–Wiechert potential – Wikipedia

Planck, Deutsche Physikalische Gesellschaft, Vol. Only electromagnetic wave effects depend fully on the retarded time. I have corrected the section reference. The rest, you seem to just be repeating the results, but not really address my argument.

Views Read Latest draft Edit View history. From Wikibooks, open books for an open world. Sign up using Email and Password. Consider, in the “primed” coordinates, a lkenard discrete charge at the origin. Feynman’s proof utilizes a geometrical and fundamental integration argument. Whitney’s solution is geometrically simpler than Lienard and Wiechert, and resolves the issue pointed out by the author. Electromagnetic radiation in the form of waves can be obtained from these potentials.

Thus, the charged particle is “smeared” out! Moreover, introducing the fluctuations of the zero point field produces Willis E.

Liénard–Wiechert potential

Covariant formulation Electromagnetic tensor stress—energy tensor Four-current Electromagnetic four-potential. Advanced fields are absorbed by the charges and retarded fields are emitted. For example, if, in a given frame of reference, an electron has just been created, then at this very moment another electron does not yet feel its electromagnetic force at all. The wischert factors are for the components of velocity pointing to the point we are measuring the potentials at.

It replaces Einstein’s “A” coefficient and explains that the classical electron is stable on Rydberg’s classical orbits.