일반물리학 2 — Magnetic Fields Due to Currents: Problem 17

17 A toroid having a square cross section, 5.00 cm on a side, and an inner radius of 19.0 cm has 460 turns and carries a current of 0.400 A. (It is made up of a square solenoid — instead of a round one as in Fig. 29-17—bent into a doughnut shape.) What is the magnetic field inside the toroid at (a) the inner radius and (b) the outer radius?