The nucleus of an atom has a charge of 65 protons.
(a) What are the direction and magnitude of the electric field at 4.9 x 10^-10 m from the nucleus?
Use Coulomb's law for the magnitude. The nuclear charge is +65 e, where e = 1.6*10^-19 Coulombs.
The direction is radially outward from the nucleus, everywhere.