So it would be a property of dipoles in fact, interesting indeed, keep us tuned!
Michel ----- Original Message ----- From: "Stephen A. Lawrence" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Friday, February 02, 2007 3:27 PM Subject: Re: [Vo]: electricity question > > > Michel Jullian wrote: >> Right, this is Paul's paradox (he does make sense occasionally ;), so >> it seems only the second and third way of looking at things >> (potential energy and work of forces) are equivalent in all cases. >> >> Maybe the paradox comes from electric and gravitational fields being >> static in nature whereas magnetic field results from a motion? > > Something just occurred to me when I read that. A "dipole" made of two > nearby monopoles shows the same effect, and we can build one of those > from electric charges. > > So, two electric dipoles will also show increasing field energy as they > draw together. > > Hmmm.... This deserves more thought... > > >> Maybe >> a full relativistic analysis could reconcile all approaches. >> >> Michel >> >> ----- Original Message ----- From: "Stephen A. Lawrence" >> <[EMAIL PROTECTED]> To: <[email protected]> Sent: Friday, February >> 02, 2007 4:38 AM Subject: Re: [Vo]: electricity question >> >> >>> >>> Michel Jullian wrote: >>>> Paul, Paul, Paul you missed my point again, never mind :) >>>> >>>> To go back to your pet theory, since as you said the formulae for >>>> field energy and potential energy are the same, there are in >>>> fact at least three equivalent ways to describe the same thing: >>>> field energy, or potential energy, or work done by the forces. >>> A minor nit to pick: Potential and field energy may be >>> interchangeable for electric fields, but apparently not for >>> magnetic fields. Permanent magnetic dipoles have potential energy = >>> -mu.B which is not tracked by the total field energy. Case in >>> point: If the field of one dipole has energy E, then the fields of >>> two widely separated dipoles have total energy 2E. Let them pull >>> themselves together until they touch end to end -- the potential >>> energy drops, but the total field energy increases, to about 4E, as >>> the two fields overlap almost exactly. (The energy density goes as >>> field intensity squared, so halving the volume while doubling the >>> intensity yields a net energy increase of 2x). >>> >>> So if we include permanent magnets in the picture, it's going to be >>> awkward to replace PE with field energy everywhere. I think this >>> may be what led Paul to assert that nobody knows where the energy >>> comes from in this case. >>> >>> >>>> All in all the third way: >>>> >>>> Kinetic energy change = Work done by the forces >>>> >>>> seems the most sensible to me as it is universal (functions with >>>> all types of forces), it is not 'potential', and it is also the >>>> most fundamental since fields are defined from forces, not the >>>> other way round as is commonly thought. >>>> >>>> How does the work approach fit with your violation theory? >>>> >>>> Michel >> >
