2.8 A small test charge is placed 20 mm to the right of sphere B, on the same plane. If the charges on both A and B is -3,58 nC and the repulsive force of sphere A on sphere B is 0,028 N to the right: A B 20 mm 20 mm Calculate the net electrostatic field on p, due to charges A and B. 2.9 The charge on B is now changed to be positive, 3,58 nC. (6)​