일반물리학 2 — Maxwell's Equations; Magnetism of Matter: Problem 41

41 As a parallel-plate capacitor with circular plates 20 cm in diameter is being charged, the current density of the displacement current in the region between the plates is uniform and has a magnitude of 15 A/m². (a) Calculate the magnitude B of the magnetic field at a distance r = 50 mm from the axis of symmetry of this region. (b) Calculate dE/dt in this region.