From Physics Lab to Museum Demo: The Many Lives of the Van de Graaff Generator

This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.

The Van de Graaff generator was built for a serious purpose: producing the high voltages nuclear physicists in the late 1920s and 1930s needed to accelerate charged particles into targets and study the resulting reactions. In that original role it served for decades as one of the standard tools of early particle physics, before newer accelerator designs such as the cyclotron and later the synchrotron overtook it for reaching the highest energies. The high voltages a Van de Graaff generator can produce, up to about 5 megavolts in the largest modern versions, also found lasting practical use well outside particle physics, including in medical radiation therapy equipment and in industrial X-ray generators. The device's second life is a far more public one. A small tabletop Van de Graaff generator, capable of producing on the order of 100 kilovolts, is cheap and safe enough to build for classroom and museum demonstrations, and it has become one of the most recognizable pieces of apparatus in popular science education: a volunteer places a hand on the metal sphere, and as their body becomes charged along with it, each individual strand of their hair, carrying the same electric charge as every other strand, repels its neighbors and stands on end. The demonstration works precisely because of the same physical principle that made the device useful to physicists in the first place, that charge delivered to a conductor spreads itself out to minimize the energy stored in the resulting electric field, distributing evenly across every available surface, hair included.