Van de Graaff Generator

Voltages of hundreds of thousands of volts can be generated with a demonstration model Van de Graaff generator. Though startling, discharges from the Van de Graaff do not represent a serious shock hazard since the currents attainable are so small.
A pulley drives an insulating belt by a sharply pointed metal comb which has been given a positive charge by a power supply. Electrons are removed from the belt, leaving it positively charged. A similar comb at the top allows the net positive charge* to spread to the dome.

A favorite demonstration with the Van de Graaf is to make someone's hair stand on end.

Other demos

Click on image for more.

Experimenters Erin Klein Jacobs above and Nehlia Grey at left demonstrate the reality that like charges repel. The strands of their hair all have the same net charge and therefore repel each other strongly.

*electrons are of course the mobile charge carriers.

Index

Voltage concepts

R Nave

Go Back

Van de Graaff Generator

Voltages in excess of 100,000 volts can be generated with a demonstration model Van de Graaff generator. Though startling, discharges from the Van de Graaff do not represent a serious shock hazard since the currents attainable are so small.
Such voltages are enough to make your hair stand on end! Like charges on individual hairs makes them repel each other and stand away from Jennifer's head. She is standing on a wooden chair to isolate her from ground so that the charge will build up on her.