Quote:
Originally Posted by DrRocket
QUOTE=korjik;1258118 Do you do much physics?
Nice hypothetical, but not germane to the original estimate and coclusion that E + V X B = 0 with no further qualifications. This is the first mention of a 100 GHz wave or a linearly decreasing B field over a spanof 1ms. Other assumptions would lead to other conclusions. I really don't care how it is done in some textbook if the fundamental mathematics is as you represent it. Non-rigorous symbol manipulations have led to erroneous conclusions before. So, can you come up with a justification for your estimate and back it up rigorously? All that I am looking for is solid mathematics and justified approximatioins. Rigor will convince me. Bluster and attempts at intimidation will not.
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Where is the math not solid and the approximations not justified?
If you do not understand my explanations, you need to get a plasma physics book and do the problems yourself. This forum is too limited in its ability to display math to make it possible to do the full derivations here.
As to E+vxB=0 there are alot of further qualifications. It is assumed that nJ is small because in most cases nJ is small (n=eta for this). The assumption is based on measurement. It isnt dogma that requires the assumption, but practice. There will be times when nJ ends up not being small and then you have to use different methods.
You seem to think that E+vxB=0 is a dogma that is prayed to. It isnt. It is a handy shortcut that applies in a set of circumstances. Plasma physics is pretty much all handy shortcuts and approximations because going back to the general form is generally unsolvable.
I cannot explain it any better here. Mathmatical rigor is not a property of physics. Plasma physics even less so. If you are looking for 'apply equation x to get the exact answer', you wont find it. If you want to learn how the physics is done, go get yourself a book and do it. That is really the only way you will learn it.
P.s. watch your quotes and unquotes when posting please. Sometimes hard to see what is your and not.