Van de Graaff generator
Overview
Electrostatic generator
An electrostatic generator, or electrostatic machine, is a mechanical device that produces static electricity, or electricity at high voltage and low continuous current...
which uses a moving belt to accumulate very high voltage
Voltage
Voltage, otherwise known as electrical potential difference or electric tension is the difference in electric potential between two points — or the difference in electric potential energy per unit charge between two points...
s on a hollow metal globe on the top of the stand. It was invented in 1929 by American physicist Robert J. Van de Graaff
Robert J. Van de Graaff
Robert Jemison Van de Graaff, was an American physicist, noted for his design and construction of high voltage generators, who taught at Princeton University and MIT.-Biography:...
. The potential differences achieved in modern Van de Graaff generators can reach 5 megavolts. The Van de Graaff generator can be thought of as a constant-current source connected in parallel with a capacitor
Capacitor
A capacitor is a passive two-terminal electrical component used to store energy in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors separated by a dielectric ; for example, one common construction consists of metal foils separated...
and a very large electrical resistance.
A simple Van de Graaff-generator consists of a belt of silk, or a similar flexible dielectric
Dielectric
A dielectric is an electrical insulator that can be polarized by an applied electric field. When a dielectric is placed in an electric field, electric charges do not flow through the material, as in a conductor, but only slightly shift from their average equilibrium positions causing dielectric...
material, running over two metal pulleys, one of which is surrounded by a hollow metal sphere.
