Invented in 1929 by American physicist Robert Van de Graaff, the Van de Graaff generator is a device in which electrically charged particles are sprayed on a moving belt and carried to an insulated terminal in a hollow metal sphere, building up to create a lightning-like discharge. The first model was made using an ordinary silk ribbon from a five-and-dime store, but later models proved capable of generating millions of volts. Where is the world’s largest Van de Graaff generator on display? Discuss