Re: [Phys-l] RC Discharge

[John Mallinckrodt <ajm@csupomona.edu>]

John Denker wrote:

> Vern Lindberg wrote:
>
> >  Current is a vector?????
>
> Yes, current is a vector.  It has direction and magnitude.
>
> We would have big problems with the Biot-Savart law
> (among other things) if it weren't.
>
> >  Current density is, but not current.
>
> If current density is a vector, then I sum up all the
> current density in some area to get the current.
> Summation does not change the vectorial character.

There may be merit to this approach, but I sure don't immediately see 
it and it's certainly nonstandard.  Frankly, I'm not sure what it 
means to "sum up all the current density in some area."  Are you 
referring to the integral of j_vector times da over some surface?  If 
so, what is the meaning of this quantity and, more importantly, what 
is its advantage over the more conventional "flux of the current 
density," i.e., the integral of j_vector dot da_vector over the same 
surface?

--
John "Slo" Mallinckrodt

Professor of Physics, Cal Poly Pomona
<http://www.csupomona.edu/~ajm>

and

Lead Guitarist, Out-Laws of Physics
<http://www.csupomona.edu/~hsleff/OoPs.html>