[Phys-L] Re: Elecric Field Lines

[John Mallinckrodt <ajm@CSUPOMONA.EDU>]

Bob wrote:

> JM wrote:
> | . . .
> | Just yesterday I had every student in a junior E and M class tell me
> | that, if Cvector dot Avector = Cvector dot Bvector for any Cvector
> | then we can cancel the Cvector on both sides of the equation and
> | determine that Avector = Bvector.  That is the right answer, and the
> | argument is appealing, but it is, nevertheless, wrong.
> | . . .
>
> Perhaps they were inferring "for any Cvector" to mean "for any and all
> possible Cvectors"

And so they should have for that is what it means.  Indeed, the
result simply isn't true otherwise.  But I can assure you, based on
how long it took me to make them understand the critical importance
of that fact, that they weren't inferring any such thing!

--
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>
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