Recent content by Meir Achuz

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    Undergrad The Electric Displacement, ##\mathbf D##

    In Gaussian units, which I use, ##\mathbf E##=q##\mathbf r##/r^3 & ##\mathbf D=\mathbf E+4\pi\mathbf P##.
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    Undergrad Small question about constantly accelerating charges

    I meant applying his equivalence principle to EM radiation.
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    Undergrad Small question about constantly accelerating charges

    The papers I have seen do not mention whether the antenna is accelerating or not. My feeling is that AE never mentioned EM when he stated the equivalence principle, and died drying to combine Relativity and EM.
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    High School Electric Fields inside Conductors & Gauss' Law

    We derive Gauss's law from Coulomb's law for a single point charge. We start with the surface integral, $$ \oint {\bf dA}\cdot{\bf E}=q \oint{\bf d A}\cdot\frac{{\bf r}}{r^3}, $$ of the normal component of ##{\bf E}## over a closed surface surrounding the point charge. The vector...
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    Undergrad Does a Point Charge in Classical Electromagnetism Possess Self Energy?

    Thanks for your interest, but I guess we are at an impasse. The quote was something like, “with all the new math being applied to my theory, I hardly understand it any more myself.”
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    Undergrad Does a Point Charge in Classical Electromagnetism Possess Self Energy?

    I apologize. I shouldn't have used that word in a technical discussion thread. The point was to show by the insert where taking 'self energy' too seriously can lead.
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    Undergrad Does a Point Charge in Classical Electromagnetism Possess Self Energy?

    It was a joke, but read the insert. I appreciate that you have expended time and knowledge on my post, which I had thought was straightforward. I certainly didn't mean to bring Einstein into it. We have some agreement, but I will comment on some things: 1. You wrote,"So in principle, we can...
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    Undergrad Does a Point Charge in Classical Electromagnetism Possess Self Energy?

    Of course, I mistyped. It should have been, it IS there by absence. I did write, "This PDF shows that a point charge in classical electromagnetism has no 'self energy'." That's because there is no self energy term in the sum of charges. Thank you for pointing it out. Since the continuous...
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    Undergrad Does a Point Charge in Classical Electromagnetism Possess Self Energy?

    This is getting silly. Neither of us will be convinced, but you keep putting up half truths, half wrong. I will try again. You neglect what you don't want. Jackson's equations 1.47, 1.48, 1.49, 1..50 clearly show there is no i=j term. For some reason, he says it in words for Eq,. (.51). You...
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    Undergrad Does a Point Charge in Classical Electromagnetism Possess Self Energy?

    Don't ignore the footnote, which I have attached. Jackson points out that infinitesimal charge is mathematical and NOT PHYSICALLY POSSIBLE, The point here is that to define E, even a small charge can polarize the source of E, making the force equation bilinear. It is completely different for...
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    Undergrad Does a Point Charge in Classical Electromagnetism Possess Self Energy?

    I thought you would recognize Griffiths. Actually, the shoe is on the other foot. Can you cite a textbook reference that justifies and agrees for an electron in the case where its charge is infinitesimal??
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    Undergrad Does a Point Charge in Classical Electromagnetism Possess Self Energy?

    "Chapter2 Electrostatics so,ifyouhavesetthereferencepointatinfinity, W=QV(r)." You added the word "infinitesimal". "W= 1/ 8π\\epsilon_0 sum n i=1 n j=i qiqj/rij (2.41) (wemuststillavoidi=j,ofcourse)."
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    Undergrad Does a Point Charge in Classical Electromagnetism Possess Self Energy?

    This PDF shows that a point charge in classical electromagnetism has no 'self energy'.
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    High School Understanding Newton's Third Law and the Net Force on Objects

    Reading this thread, I see why students always get a third law question wrong.