XPost: sci.electronics.design   
   From: fizzbintuesday@that-google-mail-domain.com   
      
   Tim Williams wrote:   
   > B is flux density: wrap a loop of wire around a given cross-sectional   
   > area, of uniform flux density B, and you get B*A flux in that loop   
   > (which if the flux is changing, you can do Faraday's law, etc.).  Who   
   > knows what current flows in the wire.   
   >   
   > Conversely, put some current into a loop of a given perimeter, and   
   > you have some magnetic field intensity H within it (give or take   
   > geometry, of course).  Who knows how much flux that took.   
   >   
   > In space, the ratio of these two happens to be mu_0.  Or at the   
   > terminals of the loop, its inductance: H == V.s / A.  For general   
   > materials, use mu = mu_0 * mu_r, and the effective cross sectional   
   > area A_e and effective path length l_e.   
      
   I think Phil understood best what I meant, but all the answers (except   
   Kevin Bacon) contributed something helpful.  Thanks so much.   
      
   A few things.   
      
   Where do you measure l_e?   
      
   What is V_s?   
      
   And you seem to be relating inductance H to mu, but isn't that a whole   
   different H?  Inductance doesn't depend on current for one thing.   
      
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