(a) On a copy of Fig. 4, illustrate the shape of the field (in the plane of the page) within and beyond the shield by drawing field lines from the sphere to the shield and in the space beyond the open end. earthed metal shield at zero potential fig 4 (b) The electrical potential of the metal sphere in Fig. 4 is + V. On your copy of Fig. 4, draw three labelled equipotential lines at approximate potentials of V. IV and IV. (at a large distance from the shield, the charge and shield system could be considered as a point charge of 7.2 x 10 C. this value is lower than the charge on the sphere). (c) i Calculate the electric field strength at a large distance of 2.8 m from this point charge. il. The shield is maintained at zero potential by connecting it to earth. Explain why the effective point charge of 7.2 x 10" C is less than the charge on the sphere