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Ferrites, air-gaps, inductors




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From:  Malcolm Watts [SMTP:MALCOLM-at-directorate.wnp.ac.nz]
Sent:  Wednesday, February 18, 1998 3:57 PM
To:  Tesla List
Subject:  Re: Ferrites, air-gaps, inductors

Hi Ed,

> From:  Edward V. Phillips [SMTP:ed-at-alumni.caltech.edu]
> Sent:  Tuesday, February 17, 1998 11:45 AM
> To:  tesla-at-pupman-dot-com
> Subject:  Re:  Ferrites, air-gaps, inductors
> 
> "Over the weekend I fluoro'd a commercially-made rod choke, about 1/2
> inch in diameter by 5 inches long.  The inside was composed of five
> 1-inch lengths of ferrite bar, with about a 1/16 inch gap between each
> rod.  Perhaps Malcolm's comments explain why this wasn't just one solid
> ferrite bar."
> 
>     Any idea what the inductance is?  The effective permeability
> of that gapped rod core is probably less than 20, so wouldn't
> expect enough inductance to be of any use for TC work.  What 
> frequency does it operate at?  Flux density is proportional to the
> voltage across the coil and inversely proportional to core area,
> number of turns, and frequency.
> 
> Ed

Shouldn't flux density be proportional to the number of turns (rather 
than inversely proportional)? 
 
Malcolm