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
A capacitor of capacitance 2 μF is charged to a potential difference of 200 volts. After disconnecting from the battery, it is connected in parallel with another uncharged capacitor. The common potential is 40 volts. The capacitance of the second capacitor is
Two equally charged small balls A and B, placed at a fixed distance experience a force F. A smilar uncharged ball C after touching one of them is placed at a middle point between the two balls. The force experienced by ball A, is
2F
4F
Electric potential of earth is taken to be zero because earth is a good
Two spheres of radii r1 and r2 are charged to the same potential. If s1 and s2 are surface densities of charges on the two, then ratio is