Experiments show that when a charged conductor is placed in contact with the inside of a hollow conductor, all the charge on the charged conductor is transferred to the hollow conductor. In principal the charge on the hollow conductor and and its electric potential can be increased without limit by repetition of the process
May I know the reason for this? Will this be possible even if the potential of the hollow space is less than potential of the conductor?
When the charges are on the belt they feel a repulsive force due to the electric field produced by the dome of the VdG.
Whatever is driving the belt is doing work and this results in the potential of the charges increasing as they move towards the dome.
Once inside the dome the charges on the surface of the dome no longer repel the charges on the belt.
A charge on the belt only feels the repulsive force of the other charges on the belt and so moves away from them until that force (due to the charges on the belt) becomes zero and that occurs when the charge is on the outer surface of the dome.
The electric field inside the sphere of a Van de Graff generator is zero (apply Gauss's law). Electrons on a rubber belt are carried into the sphere where they repel each other and jump to a nearby conductor which takes them to the surface of the sphere. The voltage limit is determined by the size of the sphere and the surrounding atmosphere. As I recall, the machine I worked with (back in the fifties at MIT) had a sphere a couple of meters in diameter which was mounted in a tank of dry nitrogen. (The tank stood about 3 stories high.) It sustained a potential of several million volts. A much smaller Van de Graff provided a one mega-volt beam of electrons for the synchrotron. Its cylindrical tank was about 2x4 meters.
