Electronics > Projects, Designs, and Technical Stuff
Does magnetic flux surround a *ferrous* conductor?
T3sl4co1l:
You're working kind of backwards -- the external field is the same; the internal field is more intense.
Which, since the field within the conductor opposes flow of current in the conductor -- this causes the field to decay extremely quickly under the surface of the conductor.
That is to say, this is precisely why skin effect is so much more exaggerated for magnetic conductors. :-+
Tim
L_Euler:
Ampere’s law does not include a term for material or material properties. The field will be the same for all materials
Zero999:
--- Quote from: blueskull on July 01, 2019, 08:54:38 pm ---One hint: many coax cables are made from steel cores.
--- End quote ---
Why? Surely the skin depth at those frequencies with a ferrous conductor would be so tiny, the losses would be huge, or does steel stop being magnetic at high frequencies?
Rerouter:
How thin is that plating that it makes it worthwhile over straight copper?? Silver is like $450 per kg, Copper plated steel does exist...
T3sl4co1l:
It's copper and/or silver platings, the combination and thickness depends on the wire grade. You do indeed see the added losses at low frequencies, but at RF it's fine.
A related matter is plating of waveguides. Normally you'd use steel base (cheap, strong), then copper, nickel and silver (copper for bonding, nickel for diffusion barrier to prevent spontaneous alloying, silver for the intended surface), but if you order this from a plating shop without special instructions you'll find the nickel layer dominates and losses are shite. The silver has to be extra thick, several skin depths, to be worthwhile.
Tim
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