A condenser has two conducting plates of radius separated by a distance of . It is charged with a constant current of . The magnetic field at a point from the axis in the gap is
Consider a loop of radius between the two circular plates ,placed `maxially with them. Then area of the loop is
And area of the plate is
By symmetry magnetic field induction is equal in magnitude and is tangentially to tha circle at every point.
In this case , only displacement current will cross the loop. Therefore, using ampere’s Maxwell law, we have