As the seventh- and eighth-grade science curriculums have evolved to address more advanced topics, much more sophisticated equipment is in order. The Brighton Education Fund has funded the purchase of several pieces not often found in middle school science labs, including an exciting Van de Graaf generator.
The Van de Graaf generator, in nuclear physics, is an electrostatic machine for the generation of extremely high voltages. It was developed in 1931 by American physicist Robert J Van de Graaf. The generator consists of a high voltage terminal in the form of a metal sphere, mounted at the top of an insulating column. A continuous belt of a dielectric material such as rubber-impregnated cotton runs from a pulley at the base of the column to a pulley within the sphere. As the belt continuously picks up electrostatic charges and delivers them to the sphere, a potential difference of as high as 5 million volts is built up.
A Van de Graaf generator can be used to illustrate how static electric charges can be developed. The classic and entertaining demonstration is to have a student with medium-length straight hair touch the sphere, causing his or her hair to stick up and out.
story by Ed Chi and Lawrence Root
photo by Gretchen Shafer
May 28, 2001