Re: [Vo]:Black Holes from Newtonian Gravity? - discs.gif - segements.gif

[Michel Jullian]

2008/10/15 Horace Heffner <[EMAIL PROTECTED]>:
...
> Agreed!  It appears I am mistaken about the field lines near the plane of a
> finite 2D disc.  I was confused by thinking I knew the field lines at a
> charged surface become normal to the surface as you approach the surface (in
> the limit).  This only applies to conductors, where the charges are free to
> redistribute to make this so.
...

Nope, no such redistribution required, only uniform charge
distribution. Perpendicularity of E field to uniform sheet of charge
easily shown using Gauss law:
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/elesht.html#c1
Infinity of the sheet of charge is not required either, provided one
is much closer to the sheet than to its edge (Gauss box much thinner
than wide => flux through the sides can be neglected).

Michel