Experiments show that the charge on a conductor stays on the
surface. 



Consider a situation in which two points on
the surface of a conductor are at different potentials. In this
situation free electrons at one point have more potential energy
than at the other point and so they will move. The movement of
charge will stop when all points on the surface are at the same
potential. 



Conclusions: 

N.B. These conclusions apply when considering static
conditions in a perfect conductor. 

1. All points on the surface of a charged conductor are at the
same potential. 

2. There can be no electric field in a conductor. 



Experiments also show that there is no field inside a
hollow charged conductor. 



Potential due to a Charged Hollow Metal Sphere 



Outside the sphere the charge can be considered to be a point
charge placed at the centre. 

Therefore 



assuming the sphere is in a vacuum. 

Inside the sphere, there is no electric field so all
points are at the same potential as the surface. 

Therefore 


