On Tue, 19 Jun 2007 05:28:29 -0700, dpierce wrote:
> Uh, ignoring core losses and other parasitics,
> you'll get whatever inductance you get inductance
> you get at ANY frequency. You don't get "millihenries
> at 50 Hz", you get millihenries.
Only if the core is air, or vacuum.
The permeability of any ferromagnetic core varies with frequency, hence
the inductance of a coil wound on such a core will vary with frequency,
too.Some ferrites would be totally useless at 50 Hz. Laminated silicon
iron stampings would work at 50 Hz and be no good at, say 100KHz.
This is different from "core losses", which are resistive.
The *apparent* inductance will be affected by winding capacitance as well.
Above its self-resonant frequency, an "inductor" looks like a capacitor.
There's nothing wrong with Tomi's statement.
--
"Electricity is of two kinds, positive and negative. The difference
is, I presume, that one comes a little more expensive, but is more
durable; the other is a cheaper thing, but the moths get into it."
(Stephen Leacock)
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