Capacitor plates in two frames *
A capacitor consists of two parallel rectangular plates with a vertical separation of 2 cm. The east--west dimension of the plates is 20 cm, the north--south dimension is 10 cm. The capacitor has been charged by connecting it temporarily to a battery of 300 V. What is the electric field strength between the plates? How many excess electrons are on the negative plate? Now give the following quantities as they would be measured in a frame of reference that is moving eastward, relative to the laboratory in which the plates are at rest, with speed 0.6c: the three dimensions of the capacitor; the number of excess electrons on the negative plate; the electric field strength between the plates. Answer the same questions for a frame of reference that is moving upward with speed 0.6c.