In a conducting hollow sphere of inner and outer radii 5 cm and 10 cm, respectively, a point charge 1 C is placed at point A, that is 3 cm from the center C of the hollow sphere. An external uniform electric field of magnitude 20 N/C is also applied. Net electric force on this charge is 15 N, away from the center of the sphere as shown in the figure. Find the magnitude of net force exerted on the charge placed at point A by the induced charges on the sphere.