using Gauss law obtain in the expression for electric field intensity at a point outside a charged hollow sphere
Let, R be the radius of the shell and Q be the charge uniformly distributed on the surface.
i) For a point outside the shell :
E×4pi r^2 = Qen/epsilon
From this equation you can easily find the equation of electric field outside the hollow sphere. But inside the hollow sphere there is no enclosed charge present so E=0 inside the sphere.