Van de graff generator
Van De Graaff Generator
Construction and Working :-
It consists of a large metal sphere mounted on high insulating supports. An endless belt b, made of insulating material such as rubber, passes over the vertical pulleys P1 and P2. The pulley P2 is at the centre of the metal sphere and the pulley P1 is vertically below P2. The belt is run by an electric motor M. B1and B2 are two metal brushes called collecting combs.
The positive terminal of a high tension source (HT) is connected to the comb B1. Due to the process called action of points, charges are accumulated at the pointed ends of the comb, the field increases and ionizes the air near them. The positive charges in air are repelled and get deposited on the belt due to corona discharge. The charges are carried by the belt upwards as it moves. When the positively charged portion of the belt comes in front of the brush B2, by the same process of action of points and corona discharge occurs and the metal sphere acquires positive charges. The positive charges are uniformly distributed over the surface of the sphere. Due to the action of points by the negative charges carried by the gas in front of the comb B2, the positive charge of the belt is neutralized. The uncharged portion of the belt returns down collects the positive charge from B1 which in turn is collected by B2. The charge transfer process is repeated. As more and more positive charges are imparted to the sphere, its positive potential goes on rising until a surface maximum is reached. If the potential goes beyond this, insulation property of air breaks down and the sphere gets discharged. The breakdown of air takes place in an enclosed steel chamber filled with nitrogen at high pressure.
Made By :- 1. Amit Saini (13BCL003)
Construction and Working :-
It consists of a large metal sphere mounted on high insulating supports. An endless belt b, made of insulating material such as rubber, passes over the vertical pulleys P1 and P2. The pulley P2 is at the centre of the metal sphere and the pulley P1 is vertically below P2. The belt is run by an electric motor M. B1and B2 are two metal brushes called collecting combs.
The positive terminal of a high tension source (HT) is connected to the comb B1. Due to the process called action of points, charges are accumulated at the pointed ends of the comb, the field increases and ionizes the air near them. The positive charges in air are repelled and get deposited on the belt due to corona discharge. The charges are carried by the belt upwards as it moves. When the positively charged portion of the belt comes in front of the brush B2, by the same process of action of points and corona discharge occurs and the metal sphere acquires positive charges. The positive charges are uniformly distributed over the surface of the sphere. Due to the action of points by the negative charges carried by the gas in front of the comb B2, the positive charge of the belt is neutralized. The uncharged portion of the belt returns down collects the positive charge from B1 which in turn is collected by B2. The charge transfer process is repeated. As more and more positive charges are imparted to the sphere, its positive potential goes on rising until a surface maximum is reached. If the potential goes beyond this, insulation property of air breaks down and the sphere gets discharged. The breakdown of air takes place in an enclosed steel chamber filled with nitrogen at high pressure.
Made By :- 1. Amit Saini (13BCL003)