In the expression qV (r) for potential energy of a charge q, V (r) is the
potential due to external charges and not the potential due to q As seen
in point 5, this expression will be ill-defined if V (r) includes potential
due to a charge q itself Rationalised 2023-24
Electrostatic Potential
and Capacitance
79
7 A cavity inside a conductor is shielded from outside electrical influences