일반물리학 2 — Maxwell's Equations; Magnetism of Matter: Problem 26

26 The circuit in Fig. 32-26 consists of switch S, a 12.0 V ideal battery, a 20.0 MΩ resistor, and an air-filled capacitor. The capacitor has parallel circular plates of radius 6.00 cm, separated by 3.00 mm. At time t = 0, switch S is closed to begin charging the capacitor. The electric field between the plates is uniform. At t = 250 μs, what is the magnitude of the magnetic field within the capacitor, at radial distance 3.00 cm?