일반물리학 2 — Maxwell's Equations; Magnetism of Matter: Problem 52

52 A parallel-plate capacitor with circular plates of radius 40 mm is being discharged by a current of 6.0 A. At what radius (a) inside and (b) outside the capacitor gap is the magnitude of the induced magnetic field equal to 60% of its maximum value? (c) What is that maximum value?