Why the Van de Graaff generator is enclosed inside an earth connected steel tank filled with air under pressure?

Van de Graaff generator is used to

State the principle of Van de Graaff generator.

In a Van de Graaff type generator a spherical metal shell is to be a 15 xx 10^6 V electrode. The dielectric strength of the gas surrounding the electrode is 5 xx 10^7 Vm^-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.)

The top of the atmosphere is at about 400 KV with respect to the surface of the earth, corresponding to an electric field that decreases with altitude. Near the surface of the earth, the field is about 100 Vm^-1 . Why then do we not get an electric shock as we step out of hte house into the open? Assume the house to be steel cage so there is no field inside?

With the help of labelled diagram of Van-de-Graaff generator. Explain its principle, construction and working of van-de-Graaff generator.

Answer the following: The top of the atmosphere is at about 400 kV with respect to the surface of the earth, corresponding to an electric field that decreases with altitude. Near the surface of the earth, the field is about 100 Vm^-1 . Why then do we not get an electric shock as we step out of our house into the open? (Assume the house to be a steel cage so there is no field inside!)

In filling the gasoline tank of an aeroplane, the metal nozzle of the hose from the gasoline truck is always carefully connected to the metal of the aeroplane by a wire, efore the nozzle is inserted in the tank . Explain why.