Re: How much does aspect ratio of secondary really matter

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Jared E Dwarshuis <jdwarshui@xxxxxxxxx>


Original poster: Paul Nicholson <paul@xxxxxxxxxxxxxxxxxxx>

Aaron wrote:
 > Any other gotchas associated with low aspect ratios?

Jared wrote:
 > Then the the magnetic field can no longer be considered uniform
 > within the core of the inductor and inductance is lower, then
 > predicted by the classic equation L = u Nsqrd Area/ Length

Irrelevant.  Nobody would be silly enough to expect
L = u Nsqrd Area/ Length to apply to an air cored solenoid.

--
Paul Nicholson
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From: Jared Dwarshuis

Four iterations of the closed path integral B dot ds = u (I total)
Give us the B field of ideal air cored solenoid.

We use the definition of inductance:  L = N phi/ i
Since phi equals  ( u N A i /  length ),  the current cancels from the
equation.

Then:    L = u Nsqrd A/  length

Cancellation of current in the numerator and denominator suggests that
a uniform current could be replaced with a non-uniform current,
yielding the same solution.

Just for fun, we can multiply the numerator and denominator by 4pi
getting:
L = u ( 2pi R N)sqrd / 4pi length
Since (2pi R N) is the wire length we can write:

L = u (Wire length)sqrd / 4pi length

"Horse sense is the sense that horses have, that keeps them from
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 W.C. Fields