# Are there any magnetics experts out there?

skeletal 16:20 23 Oct 08
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Not exactly a computer question, but hey!!!

I’m being a bit lazy, and have to admit I’ve half forgotten my magnetic theory, but I’m sure there is an easy answer to my question.

How many Gauss does a coil of 1000 Amp turns generate (1) in free air, (2) with an iron core?

Note carefully the units; I DON’T mean 1000 Amps per metre which would be 12.57 Gauss. I mean 1 Amp in a 1000 turn coil.

Skeletal

chub_tor 16:54 23 Oct 08

How do I convert an Amp-Turn rating to Gauss?
In the cgs system, one Gauss (B) is equal to one Oersted (H) in air. For coils longer than 5 times their mean diameter, the formula to convert Amp-Turns to Gauss is

B = H = (0.4 * pi * N * I) / coil length

where N = number of turns in the coil, I is the current in Amperes and coil length is in centimeters. As a close approximation, 2 Amp-Turns per inch of coil length develops one Oersted of magnetizing force, or a one Gauss field density, in an air core coil.

skeletal 17:45 23 Oct 08

Thanks chub_tor. I did do a Google, but in my usual incompetence I must have chosen the wrong search criteria. Perhaps I need to start another post: "How do I Google"!

I’ll play with that equation. I just need to be careful about SI and cgs units.