An electric field of approximately is often observed near the surface of the Earth. We may assume that this field is the same over the entire surface. We have to calculate the electric potential of a point on the surface.

Solution:             Click For PDF Version

Earth is a sphere of radius . If the electric field is approximately uniform near the surface of the Earth, we may say that it is equivalent to the field produced by an amount of charge Q at the centre of the Earth.

That is

.

Electric potential of a point on the surface of the Earth will therefore be equal to