The following surprised me a little. I’m curious what you all think. I asked Mathematica to solve this problem numerically.
Consider a circular, uniformly charged metal disk of radius 10 (in whatever units you like).
Start at a point directly above the center of the disk, say at height 1. Now move radially outward at the same height.
Since we started close to the disk (relative to the radius) we expect the net electric field to stay approximately constant as we move radially. But what does it do exactly: decrease a bit, stay exactly constant, increase a bit, or some combination (such as first decrease and then increase) as we move to a position at height 1 and radius 9?
ps: I just switched my PHYS-L subscription to non-digest mode, because I haven’t received any digests from the list in weeks even though the archives tell me there have been postings. I’ll hope to see this message echo back to me after I click send.