Solve the all parts of given question:
Question: A metal sphere of radius 14 cm has a net charge of 2.9E-8 C.
Part I: What is the electric field at the sphere's surface?
Part II: If V = 0 at infinity, what is the electric potential at the sphere's surface?
Part III: At what distance from the sphere's surface has the electric potential decreased by 490 V?
I don't know how to get that answer for the above questions. Please help! Thanks.