Consider two concentric, insulated, metallic hemispheric shells of radius a, where the top hemispheric shell is held at a constant potential (DD and the bottom one is held at the opposite value ( c110). Assume a point charge q located outside the spherical shells along the x-axis at (d, 0.0), where d > a. Find the scalar potential along the z-axis: (O, 0, z) for z>a