PHY 303L-A sphere of radius R1 has a uniform charge density

PHY 303L-A sphere of radius R1 has a uniform charge density

Subject: Physics    / General Physics
Question
A sphere of radius R1 has a uniform charge density ? within its volume except fora small spherical hollow of radius R2 located a distance a from the center.Find the E?eld at the center of the hollow, and ?nd the potential at the same point,assuming the potential is zero in?nitely far away from the sphere.