From: Paul
Date: Sun, 07 Jan 2001 02:16:12 +0000
Subject: Re: [TSSP] pn2511 is baloney
On the 27th, Bert wrote: > the Current and Voltage Amplitudes chart shown on page 12 > is an eye-opener - especially the current profile! ... > Have there been any current measurements that empirically > confirm the predicted maximum at around 1/3 of the way above > the grounded base? Re-reading some of my favourite papers, I came across a reference in G. Breit, "Distributed Capacity of Inductive Coils", Physical Review, Jun 1921, V17, Part 6, p649-677 Breit performs a mathematical analysis of the solenoid, (one of the earliest and best that I've found) and by formulating expressions for the distributed capacitance and mutual inductance using charge rings and current filaments, somewhat as we do, he uses some approximations to come up with similar differential equations for the case of very small h/d. I'd forgotten that at the end he presents voltage and current distributions measured on a h/d=0.114 coil, and lo and behold, his current profile for the grounded base configuration shows a nice rise to a peak at 40% elevation with a current 15% higher than the base current - a familiar shape. Incidently, to ensure minimum disturbance to the coil when measuring the currents, he viewed the galvanometer through a telescope! Cheers, -- Paul Nicholson, Manchester, UK. --
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.