Magnet Myths and Misconceptions

[TinselKoala]

I believe that multi-strand wire has less resistance than a solid wire of the same diameter.  (I think)  Does this mean that the strands are insulated individually themselves from each other like magnet wire?  Or, is it just a bunch of small, bare wires (all shorted together) having more additive surface area?  I guess I am being lazy here as I could just look this up.

Bill

ETA  I just read that due to the skin effect, multi-strand wire will have less resistance as most of the current flows along the surface of the individual wires.  I have no idea if this is true or not but googled it and read this in several places.

Litz wire.

http://en.wikipedia.org/wiki/Litz_wire

[TinselKoala]

Is there such a thing as "skin effect" where there is more conduction on
the surface of a conductor? Multi-strand wire ought to have good performance.

Yes, and "skin depth" is related to the frequency of the AC current being conducted. The higher the frequency the shallower this depth, in most materials. This is, in part, why people can get away with taking the discharge of a high voltage Tesla coil to their body. The current may be quite high... I have lit up incandescent light bulbs with body-conducted Tesla coil current -- but it travels on the surface of the skin rather than through the body. As long as the points of entry and exit are protected from the direct spark, one feels nothing.
And this is indeed why Litz wire is often used in coils that are to operate at high frequencies.

[poynt99]

You have got to get past these "why" questions, though.

I disagree. The how is the most interesting part in my opinion.

Once the field is there, how to calculate its strength and everything else about it is "old hat" so to speak.

Every text and web page I've looked at seems to skirt around the actual mechanism of how the field is created. I'm sure however that there is a simple explanation.

[TinselKoala]

Quote from: TinselKoala on Today at 01:50:07 AM

You have got to get past these "why" questions, though.

I disagree. The how is the most interesting part in my opinion.

Once the field is there, how to calculate its strength and everything else about it is "old hat" so to speak.

Every text and web page I've looked at seems to skirt around the actual mechanism of how the field is created. I'm sure however that there is a simple explanation.

See what you did there? "How" and "why" are not really the same question.
As I understand it, there are a few "free parameters"  in the modern physical description of reality. Not many, only like sixteen or something like that. Everything else takes its calculated or derived value from the seemingly arbitrary values we see of these free parameters. Nobody knows just "why" these parameters take on the values they do, but what is known is that if any of them were even slightly different, the world would be very much different. For example, let the fine structure constant be only a few percent different... and no stars can form. The situation is kind of like Euclid's Axioms. Nobody knows "why", on a perfect plane, two parallel lines never intersect. But it's easy to see _how_ that happens (or rather doesn't happen) and to use that fact to prove, with mathematical certainty, other theorems about geometry.

Sure, the explanation you seek is simple. If it were otherwise... we would not be around to see it. Eventually, when we ask "why" something in Physics is the way it is, we bump up against the Anthropic Principle, weak or strong. And as you know these explanations are less than satisfactory.

So, humans invented Religion. God did it, because He wanted it to be that way. See, it says so right here in the (insert favorite holy book here).

[Newton II]

Sure, the explanation you seek is simple. If it were otherwise... we would not be around to see it. Eventually, when we ask "why" something in Physics is the way it is, we bump up against the Anthropic Principle, weak or strong. And as you know these explanations are less than satisfactory.

You are absolutely right.   Sun always rises from the East and not from the West -   "why?" -  because God feels that East is better than West!!  (Waste!!)