Question

Describe Van-de-Graaff generator under the following points:
(i) Labelled diagram
(ii) Principle
(iii) Uses (any two)
(iv) Disadvantage.

Answer 1

(ii) Principle: We know that the capacity of a uniformly charged hollow spherical conductors is $C=4\pi {\epsilon }_{0}R$. Obviously, for the capacity to be large the radius $R$ should be large. Further at the pointed ends of a charged conductor the surface density of charge (i.e., charge/area) is more as compared to any plane surface, therefore the electric field near the pointed ends of conductor is more stronger than at any other places. The working of Van-de Graff generator is based on these facts.

(iii) Uses:

(i) To generate high voltage.

(ii) To accelerate $\alpha$ particles, protons and dentrons etc in nuclear disintegration.

(iv) Disadvantage: Due to its large size it is not convenient to carry it from one place to another.