- #1

zmorris

- 13

- 0

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/wirfor.html

F/L = u0*I1*I2/(2*pi*r)

And the general formula here:

http://en.wikipedia.org/wiki/Ampère's_force_law#Equation

It's easiest to see the formula in the link because it contains integrals.

The problem is, I've been out of college too long and my brain is suffering from petrification. I've always had a hard time visualizing line integrals. My guess is that when parallel wires are bent into a ring, each infinitesimally small section of wire will feel an increasing force as the opposite section of wire is bent closer to it. So probably the 1/2pi term will fall away when the wires are formed into a circle. I'd like to work the integral to know for sure, but can't remember how to do it.

A simpler question related to this is: when we find the force per length on one wire with respect to the rest of the wire, what is the radial force outward with respect to the origin? I think it's half as much because the force on each radius added together would total the force across the ring.

So my best guestimate is that the radial force per length anywhere on the ring is:

F/L = u0*I/2

But it seems that the "elegant" solution would be:

F/L = u0*I

Can anyone do better?

Thanks for your help,

Zack Morris