Calculate the capacitance of the earth of radius 6400 km .

The capacitance of spherical conductor of radius 10 m is

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

Calculate the potential energy of hydrogen atom of radius 0.53 A^@ .

A man weight 60 kg-wt at the earth's surface The radius of the earth is 6400 km. At what height above the earth's surface, his weight becomes 30 kg wt ?