Final answer:
The expression for the electric potential due to an insulated charged sphere at different points can be found using Gauss's law.
Step-by-step explanation:
The expression for electric potential due to an insulated charged sphere at the outer point, surface, and inner point can be found using Gauss's law. For points outside the sphere, the potential is the same as that of an isolated point charge located at the origin. The potential at the surface of the sphere and at points inside the sphere can be determined by integrating the electric field over a closed spherical surface centered at the sphere.