Recent content by particlezoo

It may be more instructive to think about multiple capacitors in series vs. parallel before modifying an individual capacitor by itself. When you have capacitors in parallel, they have the same voltage V. So using U = CV^2 / 2 makes sense for capacitors in parallel. Also, capacitors in parallel...

I consider it to be a feature of the solution. The main crux as it turned out was how the voltage was going to scale with the square of the relative velocity between the electric charge and the conductive loop, meaning that one may expect the induced current in the loop to increase with the...

I know it has been over a year since I posted this thread, but here is a thought that I had been holding back from this discussion: The following quote is from Prof. Akira Hirose's lecture notes from course P812: http://physics.usask.ca/~hirose/p812/notes/Ch10.pdf So, if I had a conducting...

Hmmm... in the limiting case where there is just an (approximate) plane wave traveling at c, there is a "displacement current density" orthogonal to the wave vector. So the displacement current doesn't necessarily "propagate". But in the real world, we can have (approximate) plane waves...

To put this in another way, is there some reason from first-principles as to why we have j as the spatial component of the four-current rather than the total current density which includes the displacement current? Has anyone tried to see what the experimental consequences of this would be? Kevin M.

In that case, perhaps one can consider the electric field observed in a particular frame of interest, and be concerned not with the exact quantity of electric work that is done, but rather be concerned with whether that electric work is simply positive or negative, larger or smaller, and how...

The one I described in my reply, implicitly.

Ok. So last night I came up with idea of describing my scenario in terms of other scenarios, like some sort of special case of a special case. So for the vast majority of the scenarios, what I am essentially trying to do is picture a magnet and a charge, with the magnet being a relatively...

The setup for one magnet Introduce a magnet: Inertial Frame 1 (or lab frame) A frame where a magnet is seen to move with uniform velocity v and carries a uniform polarization P while a point charge Q is seen to be stationary at time t=0. Inertial Frame 2 (or material frame) A frame where a...

Here is a paper that may help explain what I mean by "V(x,y,z)" "Electromagnetic interactions derived from potentials: charge and magnetic dipole" by Roberto Coïsson https://arxiv.org/pdf/1403.0973.pdf However, he uses the symbol φ for the electric scalar potential rather than the azimuthal...

Sorry for being unclear. However, I believe that the answer was implied by the statement: So, I believe this implies that the magnetic field density B is not changing, which in turns implies that if the cylindrical magnet is rotating, it must be doing so on its axis of symmetry. It took me a...

Suppose I had cylindrically-symmetric rotating magnet surrounded by a plasma. I rotate it on its axis at a constant angular velocity, and so the electric field E produced is non-solenoidal and can be described as the negative gradient of some potential V(x,y,z). The electric field is induced...

Suppose I were to subject a polar molecule to a high-frequency electric field. The polar molecule responds to the high-frequency electric field and thus it has a time-varying electric dipole moment vector. If we treated this as a classical electric dipole, it would be expected to radiate some of...

In case if you missed this post, here it is again from above. It highlights my main concern. Of course here I am only considering what the bulk of the charge on the tube would do (i.e. the uniform contribution) under the guiding assumption that redistribution of charge can be made negligible by...

Presence reads to me a "placement", implying that the charge is only "placed" and that therefore a "location" is given, but not imply a velocity. The movement of charges that results of solely of "presence" implies then only a transient movement of charges, not a sustained current. Without a...