Chronology |
Current Month |
Current Thread |
Current Date |

[Year List] [Month List (current year)] | [Date Index] [Thread Index] | [Thread Prev] [Thread Next] | [Date Prev] [Date Next] |

*From*: "Prof. John P. Ertel" <JPE@USNA.EDU>*Date*: Fri, 16 Feb 2001 10:15:59 -0500

This thread is so long running that I'm no longer sure that I'm

answerign the right question.

But, if I do understand, then of course the total charge on any

capacitor in any normal circuit is ZERO (+q on one plate and -q on the other).

It seems to me that the "twice q" as compared to Smythe is due simply to

the question of how much charge it takes to produce a certain charge

density. For consistancy, we require the the integral of the charge

density over the surface yield q (either +q or -q depending on which plate).

+=================================+=================================+

Bob Sciamanda wrote:

This surface charge density result is just twice Smythe's result: pg 114;

eq (3).

Perhaps there is a discrepancy in what "Q" stands for; in Smythe it is the

total charge, added up over all disck surfaces.

David, I have been able to spend only sporadic moments on these things -

but I will "shortly" e-mail you some scanned pages of Smythe in TIFF

format.

Bob

Bob Sciamanda

Physics, Edinboro Univ of PA (em)

trebor@velocity.net

http://www.velocity.net/~trebor

----- Original Message -----

From: "David Bowman" <David_Bowman@GEORGETOWNCOLLEGE.EDU>

To: <PHYS-L@lists.nau.edu>

Sent: Sunday, February 11, 2001 01:44 PM

Subject: Re: capacitance of a disk

Regarding Ludwik's question:

. . .

Yes. In my most recent post I showed how to calculate the surface

charge density for this limiting flat disk case as well as for the

generic spheroid conductor case. To recap the result for the disk

the surface charge density is:

[sigma](r) = Q/(2*[pi]*R^2*sqrt(1 - (r/R)^2))

. . .

--

+=================================+=================================+

ERTEL SENDS.

{best viewed in Courier} /^\-/^\

/ \

| * |

|#########|

===========================

/ Prof. John P. Ertel \

/ USNA-NESA Faculty Rep \

/ veteran Eagle Scout \

+==============================================================+

| JPE@usna.edu or JPErtel@BigFoot.com |

| Physics Department, 9C Office : 410-293-6657 |

| Michelson Rm-338 DSN : 281-6657 |

| 572 Holloway RD FAX : 410-293-3729 |

| U. S. Naval Academy |

| Annapolis, MD 21402-5026 HomeVoice : 410-757-6618 |

| {Call HomeVoice to activate FAX/DATA} HomeFAX : 410-757-6619 |

+=======================================================

begin:vcard

n:Ertel;John P.

tel;fax:410-293-3729

tel;home:DSN: 281-6657

tel;work:410-293-6657

x-mozilla-html:FALSE

url:http://physics.usna.edu/physics/Faculty/Ertel/ertel.html

org:U. S. Naval Academy;Physics

adr:;;572 Holloway RD;Annapolis;MD;21402-5026;USA

version:2.1

email;internet:JPE@usna.edu

title:Prof.

x-mozilla-cpt:;3

fn:Prof. John P. Ertel

end:vcard

- Prev by Date:
**Re: Mpemba effect" ??** - Next by Date:
**Re: Source of Old CRT's** - Previous by thread:
**Re: capacitance of a disk** - Next by thread:
**Re: capacitance of a disk** - Index(es):