A spherical conducting shell has 12 microcoulombs of positive charge on it. The radii of the shell are r(inner)=12 cm and r(outer)=2r(inner). A particle of -4 microcoulombs is placed at the center of the shell. Provide a sketch of the electric field lines (only a few). For the following 3 reigons... r less than or equal to r(inner), r(inner) less than r less than r(outer), and r greater than or equal to r(outer). Find the charge and sign of (inner) and (outer) shell surfaces. Also find the magnitude of the electric field at 3r(inner) from the center of the sphere.