A toroid having a square cross section, 5.00 cm on a side, and an inner radius of 16.0 cm has 600 turns and carries a current of 0.700 A. (It is made up of a square solenoid bent into a doughnut shape.) (a) What is the magnitude of the magnetic field inside the toroid at the inner radius? 5.25e-4 T (b) What is the magnitude of the magnetic field inside the toroid at the outer radius? ? T I keep missing part B. I tried: B = PERMIVITY*n*I where n = N/(2PI*R); N is the number of turns: R is the radius of the toroid. PERMITIVITY = 4PIE-7; So i plugged in n = 600/(2PI*.05) B = 4PIE-7*.700*n which was wrong! any ideas?