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Re: visualizing fields near charged objects



At 08:12 AM 2/9/01 -0500, Ludwik Kowalski wrote:
1) Is it appropriate to perform simple averaging for usual
cylindrical cells (dr=const)?

No.

Averaging is not the idea. Laplacian is the idea. The two are related in
a simple way in rectangular coordinates, but the relationship is more
complicated in general.

2) If not then what to do?

The cells in the cylindrical spreadsheet represent dr by dz.
http://www.monmouth.com/~jsd/physics/laplace-cyl.xls
We know d/d(phi) is zero.

But the Laplacian is not (d/dr)^2 + (d/dz)^2.
It is (d/dr)^2 + (1/r) (d/dr) + (d/dz)^2.
So that's what to do.