A spherical insulator has a radius of R = 0.20 m and is uniformly charged with a charge density of p= 2.8 x 10-6C/m. What is the magnitude of the electric field at a point that is... (a) 0.1 m from the center of the spheres (b) 0.20 m from the center of the spheres? (c) 0.3 m from the center of the spheres? (Reminder: the volume of a sphere is R.) 4 R (b) I (a) +(c)