1. The problem statement, all variables and given/known data Consider the core of dimensions given in example 5-1. A coil requires an inductance of 23.6μH, a maximum current of 4A is allowed, and flux density is not to exceed 1.3T. Calculate the required relative permeability, μr, of the magnetic material that should be used. (HINT: You will need to consider N, the number of turns on the core. Compute this first, and use the result to find µr) 2. Relevant equations Lm = N^2/R Bm = μm*N^2/lm gamma = N*PHI PHI = N*i/Rm PHIm = Bm*Am 3. The attempt at a solution I can solve the solution IF I can solve for N, the number of turns in the core. I cannot find a way to do this. Can anyone point me in the right direction? Am I missing an equation? I've read thru class notes and our book (Electric Machines and Drives - Ned Mohan) and cannot find something that would lead to N. Thanks!