Re: wire tension

[Bob Sciamanda <trebor@VELOCITY.NET>]

From: "Ludwik Kowalski"
> Carl described alternative methods of solving this problem:
>
> > A circular loop of flexible wire is placed in a uniform
> > magnetic field perpendicular to its plane. The radius of
> > the loop is R and its current  is I. What is the tension?
>
> This was very useful to me. Thanks. I like this little
> problem because at first it is nearly a paradox. Not a single
> radial force has a tangential component but the tangential
> force, I*B*R, is not zero in the loop.

 Isn't this another version of the standard intro mechanics problem:
Push sideways on a rope stretched taught between two trees; calcuate the
resulting tension.
The rope's tensile properties convert the sidewise forces into tangential
stresses.
A three dim version would be a balloon being pumped up.

Bob Sciamanda (W3NLV)
Physics, Edinboro Univ of PA (em)
trebor@velocity.net
http://www.velocity.net/~trebor