Re: [Phys-L] magnetic circuits ... was: change in inductance with iron core

[bernard cleyet <bernard@cleyet.org>]

> On 2021/May/05, at 11:51, Carl Mungan via Phys-l <phys-l@mail.phys-l.org> wrote:
>
> Okay, that’s helpful. So how about if instead of a bar, I use a square donut so field lines can loop around through it so they never have to pass through air?
>
> This might be easier if I use iron wire, initially long pieces passing through the core, but now I bend the free ends to join them together.

Which reminds me in the v. distant past I read that transformers favored sheets while DC pulse favored iron wires.  In transformers closed mag. circuit, but in spark coils (for Crookes and X-ray tubes, auto, and early radio transmitters) only a core [1] in a solenoid (two collinear, of course).  

John, please comment.


bc   still has Model T spark coils from Pep Boys Auto.  


[1] One end which activated the interrupter.