Evaluation of electric field due to uniformly charged spherical shell (charge Q):
`text(Case 1)` `text(At external point)` (r > R)
`E(4pir^2) = Q/epsilon_0`
`E = Q/((4pi epsilon_0)r^2)`
`text(Case 2)` `text(At internal point)` (r < R)
`E(4pir^2) = 0/epsilon_0`
`E = 0`
`E(4pir^2) = Q/epsilon_0`
`E = Q/((4pi epsilon_0)r^2)`
`text(Case 2)` `text(At internal point)` (r < R)
`E(4pir^2) = 0/epsilon_0`
`E = 0`