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Electrostatic Repulsion from Van de Graaff Generator

A fun way to illustrate electrostatic forces from a Van de Graaff generator.

A Van de Graaff generator, invented by American physicist Robert J. Van de Graaff, is a kind of electrostatic generator popular in science demonstrations.

For an in-depth look at how these machines operate, please visit our Van de Graaff generator tutorial.

Lots of objects – from fluorescent light bulbs to the hair on your head— can be used with the generator to demonstrate electrostatic principles.

This tutorial shows how soap bubbles can illustrate attraction and repulsion.

Instructions

  1. Click the “bubbles” button to blow bubbles toward the Van de Graaf generator
  2. Watch how the bubbles at first are attracted to the generator, then suddenly are repulsed.

Why does this happen?

At first, the bubbles carry the charge of the person who blew them, so they’re attracted to the sphere, which carries the opposite charge. But when the first bubbles hit the sphere, they absorb its charge and are immediately repelled, popping in the process. Encountering the spray from these burst bubbles, the incoming bubbles will be repelled.