The work done in carrying a charge Q once round the circle of radius r with charge Q at the centre of the circle is
zero
A capacitor connected to a 10 V battery collects a charge of 40 μC with air as dielectric, and 100 μC with oil as dielectric. The dielectric constant of oil is
Electric potential of earth is taken to be zero because earth is a good
The electric field required to just support a water droplet of mass 10-5 g, which has a charge of 10-13 C is
107 V m-1
9.8 × 103 V m-1
106 V m-1
9.8 × 105 V m-1
