A nonconducting sphere of radius R = 5 cm has its center at the origin O of the coordinate system as shown in (Fig. 3.112). It has two spherical cavities of radius r=1cm, whose centers are at 0,3cm and 0,−3cm, respectively, and solid material of the sphere has uniform positive charge density ρ=1/πμ Cm^−3. Calculate the electric potential at point P(4 cm,0).