question_answer 35)

In a van de Graaff type generator a spherical metal shell is to be a 15 × 106 V electrode. The dielectric strength of the gas surrounding the electrode is 5 × 107 m?1. What is the minimum radius of the spherical shell required? (You will learn from this exercise why one cannot build an electrostatic generator using a very small shell which requires a small charge to acquire a high potential.)  

Answer:

Minimum radius of the shell of van de Graaff generator is given by the relation                 V = E.d i.e.                                 i.e.