Recent content by Order

  1. O

    Current phase between inductor and capacitor in LCR-circuit

    Ok, let's see if I got things right: 1. The current is (for an ideal inductor with no capacitance) equal throughout the LCR-Circuit. (This is so because of Kirchoffs first rule.) 2. The voltage is not in phase between the different parts of the Circuit but at resonance it all adds up to...
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    Galilean invariance and kinetic energy

    That will have to do if I cannot find anything else. But from what I remember the book had a single author and the argument was easier to follow. I translated it into something that a 15-year old could understand. I don't quite follow the Lagrangian argument myself actually and why you can't...
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    Galilean invariance and kinetic energy

    I tried to look this up on the internet. I know there is a book about it but I forgot its title. I know that you can prove that the kinetic energy should be proportional to velocity squared by saying that this is the only Galilean invariant definition of kinetic energy. Can someone help me...
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    Current phase between inductor and capacitor in LCR-circuit

    At resonance (## \omega_0^2= 1/LC##) in an LCR-Circuit the phase angle given by \theta=\tan^{-1}\left( \frac{\omega L - 1/\omega C}{R} \right) obviously is zero. And still there are other phases to deal with. This I don't understand. Let me elaborate. For example when calculating the amount...
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    Deflection of suspended coil (fluxmeter)

    Yes i guess it is hard even for trained physicists. Or maybe I screwed it up so much no one wants to help. No I don't understand it either. Thats why I ask for help According to my calculations above this would lead to the very unlinear differential equation \frac{d^2...
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    Deflection of suspended coil (fluxmeter)

    Homework Statement A fluxmeter is a device sometimes used for measuring magnetic fields. It is a suspended coil instrument in which the suspension has virtually no restoring twist. The instrument is used in series with a search coil which is removed from or rotated in the field to be measured...
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    Closed integral problem: field in the plane of a magnetic dipole

    Solved Yes, obviously the cosine of the angle is dependent of ##\phi## to first order. I should have understood that. I got an estimation of ##\cos \varphi ## without making this assumption (##\phi=0##) but it was half a page of trigonometric calculations and approximations! (There must be...
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    Deriving the local field and Clausius Mossotti formula in a dielectric

    Thanks, that makes me more Confident that there is more to it. I don't Think I will read Jackson in a while (I know it is chapter 4), but when I do I will keep all this in mind.
  9. O

    Closed integral problem: field in the plane of a magnetic dipole

    I have read about Biot-Savarts law but I have no idea how to solve it when the curve is dependent of some variable. My books in mathematics don't help, nor my books in physics. You are welcome to give me a link where I can read about this, but first let me know if I have got it right this far...
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    The resistance in water between two bouys

    Ok, I'm glad there was nothing wrong with my calculations or reasoning, but the problem was that I thought the bouys were submerged very Deep in the ocean! (yes the current becomes halved and the resistance doubled.)
  11. O

    The resistance in water between two bouys

    Homework Statement Two spherical buoys float half submerged in a calm deep sea. Their radius a is very much smaller than their separation b. Calculate the resistance between them if the resistivity of the water is ρ. Homework Equations R=V/I V=\int Edl I=\sigma \int_S \textbf{E} \cdot...
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    Deriving the local field and Clausius Mossotti formula in a dielectric

    (My last https://www.physicsforums.com/showthread.php?p=4424810#post4424810 post did not get much attention so I try again without all these formulae. Think this will be more clear...) To derive the local field in a non-polar dielectric you assume a very small spherical cavity in which (since...
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    Paradox in evaluating the Lorentz field in a dielectric

    Vielen dank for giving my problem attention Meir Achurz. I thought it would engage more phycisists when I am saying something is wrong. I Think it should be easy to correct a misstake. But I don't know if you have really understood my problem. (If you cannot imagine Surface charges inside the...
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    Paradox in evaluating the Lorentz field in a dielectric

    Can someone help me in understanding where I am wrong when thinking about the derivation of the Lorentz field in a dielectric. I give the derivation in italics (although the familiar reader should not need to read it) and after that I present the paradox. The basic idea is to consider a...
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    Estimating the (average local field)/(Applied field) in water

    Yes, I have covered the orientational polarizability induced by dipoles aligning with the Electric field, but with a simpler derivation than done in your linked presentation. As they hint I let the distortional polarizability be zero and then I get the quotient 6,6.
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