1. The problem statement, all variables and given/known data A torodial solenoid has inner radius r1 = .15m, outer radius r2 = .18m; turns N=250 and carries a current I = 8.50A. What is the magnitude of the magnetic field at the following distances from the center of the torus? a) .12m b) .16m c) .20m 2. Relevant equations B = [tex]\mu[/tex]0NI/2pir 3. The attempt at a solution I'm actually not quite sure as to how to use the formula given the fact that we have inner and outer radii and then different distances on top of that. I was thinking the way to solve the problem would be to find the B fields at each of the radii and each of the distances given and then subtract given by the distance, so the B field at .12m would be subtracted from the B field at .15m, and than the other 2 would be subtracted from the .18m radius, like so B1 = 2.8*10^-3T B2 = 2.4*10^-3T B(.12) = 3.6*10^-3T B(.16) = 2.7*10^-3T B(.20) = 2.1*10^-3T B(.12)-B1 = 8*10^-4T B(.16)-B2 = 3*10^-4T B(.20)-B2 = 3*10^-4T not sure if I'm correct since my answers end in terms of a Gausse with such a small current, I was also thinking that the B field at .20m from the center would be 0 since it's outside the solenoid, if anyone could point out what I'm doing wrong I'd greatly appreciate it, thanks.