If air is replaced by dielectric medium of constant K, capacitance decreases by K times increases by K times remains same. If charge is increased how does it affect the capacitance increases by two times decreases remains same. The ratio of coulombs force between two charges with air and a medium [of dielectric constant K] is 1:K K:1 1:2K. Eddy Current is induced current due to change in magnetic flux induced current due to property of conductor indeuced current due to constant magnetic flux. A cell is charged little more than required because of Eddy current induced e.m.f back e.m.f.