On Oct 17, 2008, at 10:09 PM, Michel Jullian wrote:
Ah, yes, this is what I was missing. Even though I still believe the
surface charge density is uniform on _most_ of the thin conducting
disk surface (as it is on the plates of a parallel plate capacitor), I
now realize the non-uniform charges
2008/10/16 Horace Heffner [EMAIL PROTECTED]:
On Oct 16, 2008, at 7:17 AM, Michel Jullian wrote:
But if you get closer and closer to a finite disk of charge, whether
on-axis or off-axis, it will look more and more like an infinite
sheet of charge, because the 1/r^2 law makes the effect of
On Oct 16, 2008, at 11:17 PM, Michel Jullian wrote:
2008/10/16 Horace Heffner [EMAIL PROTECTED]:
On Oct 16, 2008, at 7:17 AM, Michel Jullian wrote:
But if you get closer and closer to a finite disk of charge, whether
on-axis or off-axis, it will look more and more like an infinite
sheet
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
On Oct 15, 2008, at 11:54 PM, Michel Jullian wrote:
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
But if you get closer and closer to a finite disk of charge, whether
on-axis or off-axis, it will look more and more like an infinite
sheet of charge, because the 1/r^2 law makes the effect of the most
remote charges rapidly negligible compared to that of the closest ones
right under you.
So the
On Oct 16, 2008, at 7:17 AM, Michel Jullian wrote:
But if you get closer and closer to a finite disk of charge, whether
on-axis or off-axis, it will look more and more like an infinite
sheet of charge, because the 1/r^2 law makes the effect of the most
remote charges rapidly negligible
On Oct 14, 2008, at 7:54 PM, Robin van Spaandonk wrote:
In reply to Horace Heffner's message of Mon, 13 Oct 2008 02:08:35
-0800:
Hi,
[snip]
I disagree. You are ignoring the 1/r^2 nature of gravity or
electrostatic charge.
The field near a line charge is 1/r normal to the line. The field
I wrote: ... matter with some z axis velocity and a stable circular
orbit will essentially sustain simple harmonic motion in the z
axis ... .
That should say: ... matter with some z axis velocity and a stable
circular orbit will essentially sustain oscillating in the z axis ...
. The
... bobbing parabolas ...
Best regards,
Horace Heffner
http://www.mtaonline.net/~hheffner/
In reply to Horace Heffner's message of Mon, 13 Oct 2008 02:08:35 -0800:
Hi,
[snip]
I disagree. You are ignoring the 1/r^2 nature of gravity or
electrostatic charge.
The field near a line charge is 1/r normal to the line. The field
near a plane charge is uniform and normal to the plane.
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