question_answer 20)

Two charged conducting spheres of radii a and b are connected to each other by a wire. What is the ratio of electric field at the surfaces of the two spheres? Use the result obtained to explain why charge density on the sharp and pointed ends of a conductor is higher than on its flatter portions. 

Answer:

Two charged conducting spheres of radii a and b connected by a wire will reach to same potential.                 Using E = , we get V = Er                 Then V = E1a and V = E2b                 i.e. E1a = E2b or                 Clearly electric charge density for the pointed surface will be more because a flat surface can be equated to a spherical surface of large radius and a pointed portion to a spherical surface of small radius.