A spherical shell of a Van de Graff generator has an electric field strength E = -10000 N/C on the surface of its spherical shell R=10 cm in radius.
a) Find the net charge on the shell
b) Find the flux of the electric field through a surface at r=15 cm around the shell of the generator.
c) Find the flux of the electric field through a surface at r=30 cm around the shell of the generator. How is it related to the flux through the surface at r=15cm?