8.02 Lecture Notes - Lecture 1: Displacement Current, Capacitor, Poynting Vector
Document Summary
The b eld is counterclockwise, which means that ux is increasing in time. So positive charge is increasing on the bottom plate. Consider a charging capacitor: use ampere"s law to calculate the magnetic eld just above the top plate. B s = i i = j n a. Surface 1: i = 1 and surface 2: i = 0. We don"t have current between the capacitor plates but we do have a changing e eld. It is not a ow of change but proportional to changing electric ux. If surface 2 encloses all of the electric ux due to the charge plate, the i = i. B s = (i + i ) = j n a + / t( e n a) A capacitor consisting of circular plates of radius r separated by a distance d is in a circuit carrying the steady current i as shown.