Two concentric conducting spheres have radii of 5 and 9 cm. There is a perfect dielectric for which e, = 3.5 between them. The potential of the inner sphere is 5 V and that of the outer is -5 V Find the location of the 0V equipotential surface O a. 7.03 cm O b. 6.43 cm .23 O d. 6.83 cm . 6.03 m O f. 6.63 cm