Van de Graaff

The Van de Graaff generator is a device invented in 1929 by the physicist Robert J. Van de Graaff. It is a machine using the same effect as when you rub a balloon against the hair. It consists of a sphere on top of some support. Inside the support there is a rotating rubber band. Because of the different materials of the rubber and where the rubber band is connected, electric charge will be transferred between the materials as a result of the triboelectric effect. The process results in that charge is transferred to the sphere on top. After having the machine activated for a little while there will be a strong charge on the sphere which easily creates sparks. This charge can be utilized for raising the hair by holding a hand on the sphere.

It is in general not a dangerous device, since the electricity generated is only static, and therefore does not contain a lot of energy. The obtainable voltage is on the other hand very high.

• A simple Van de Graaff that works well