(Solved): A hollow metal sphere has 7 cm and 10 cm inner and outer radii, respectively, with a point charge at ...

A hollow metal sphere has 7 cm and 10 cm inner and outer radii, respectively, with a point charge at its center. The surface charge density on the inside surface is \( -150 \mathrm{nC} /\mathrm{m}^{2} \). The surface charge density on the exterior surface is \( +150 \mathrm{nC} / \mathrm{m}^{2} \). What is the strength of the electric field at point 12 cmcm from the center?