Re: EM Induction - A conceptual question

[Chuck Britton <britton@NCSSM.EDU>]

can this fringing still be true for a type I superconducting cylinder?

I'm not familiar with this symmetry argument for 1/2 strength at the ends.
Would you elucidate it please?



At  4:38 PM -0400  on  4/17/02,  John S. Denker   wrote
> ==================
>
> While we're on the topic of fringing fields:
>
> 1) We are all familiar with the notion that the field
> inside a long solenoid is uniform.  This is mostly true.
>
> 2) There is a widespread misconception that the uniform
> field extends all the way to the ends, so that the flux
> lines shoot straight out the end like water shooting out
> of a garden hose.  This is not right.
>
> You can easily show (by symmetry!) that the field right
> at the end of long solenoid is half the strength of the
> field at a typical point not near the end.  That means
> that half the field lines have "leaked out" sideways
> before reaching the end.  There's a whole lot of fringing
> going on.

--

 .-.     .-.     .-.     .-.     .-.     .-.     .-.     .-.     .-.     .-
    \   /   \   /   \ N /   \ C /   \ S /   \ S /   \ M /   \   /   \   /
     `-'     `-'     `-'     `-'     `-'     `-'     `-'     `-'     `-'
Chuck Britton                                   Education is what is left when
britton@ncssm.edu                               you have forgotten everything
North Carolina School of Science & Math         you learned in school.
(919) 286-3366  x224                            Albert Einstein,        1936