Calculate the capacity of the earth as a conduction sphere of radius ` 6.5 x 10^3` km.

Calculate the capacitance of the earth of radius 6400 km .

The capacity of spherical conductor of radius 10 m is :

State Ohm's law. Calculate the conductivity of a conductor of radius 0.5 mm and length 10 cm having resistance 25 Omega .

The potential at the centre of a hollow charged sphere is 900 volts. Find the charge on the sphere in micro-coulomb if the sphere is of radius 10 cm.