+ 9 + a a a a -q + 9 Fig.1 (Question 3) Fig.2(Question4) Q.3. Fig. 1 shows a spherical conducting shell of total charge of Q = -30 nC , with an inner radius a = 10.0 cm, and outer radius b = 2.00a . In addition, a small ball of charge q = 10.0 nC is located at that center. What is the magnitude and the direction of the electric field at radial distances (a)r = 0.5a, (b)r = 1.50a, and (c)r = 3.00b? (d) What is net charge on the inner surface and on the outer surface of the conducting shell? [2.5+2.5+2.5+2.5] Q.4 In Fig.2, four charges form a square assembly of charges. With V= 0 at infinity and q = 3.00 uC, and d = 4.0cm, a) what is the net electric potential at the top right corner due to these four charged particles? b) what must be the work done by the external agent to assemble this system