Exploring the Spark: How a Van de Graaff Generator Energizes Minds

Have you ever felt a slight shock when touching a metal doorknob after shuffling across a carpeted floor? That jolt is caused by static electricity, a fascinating phenomenon where electric charges build up on the surface of objects. How does this relate to the Van de Graaff generator? The Year 9 students have been finding out how this machine works and the Science behind it.

Named after its inventor, physicist Robert J. Van de Graaff, this remarkable device is designed to generate high voltages of static electricity. Imagine a large, spherical, metal dome mounted atop an insulated column. Inside this column resides a rubber belt, like a mini conveyor belt and two metal brushes.

The Inner Workings

Initially, the rubber belt starts to move, driven by a motor. As it rotates, the belt rubs against two metal brushes, acquiring a surplus of electrons. Remember, electrons are negatively charged particles. With each rotation, the surplus of electrons accumulates on the surface of the belt. According to the law of electrostatics, like charges repel each other, so the negatively charged belt repels electrons in the belt, forcing them to move upward to the dome. As electrons build up on the surface of the dome, it acquires a substantial negative charge. This process continues until the potential between the dome and the ground reaches a very high level, often in the range of thousands to millions of volts!

When a student puts a hand on the dome, the electrons will spread out onto them as they repel from the other electrons. They are most obvious in a person’s hair because the like charges of the electrons repel each other and cause the hairs to stand up and spread away from each other. Year 9 had some great fun using the machine and explaining how this works. Take a look below at some of the students new hair do’s!

Mr Dean 

Science Department

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