How Does a Van De Graaff Generator Work?

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  • 0:05 Basics of Static Electricity
  • 1:27 Van de Graaff Generators
  • 2:51 How Do They Work?
  • 3:57 Lesson Summary
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Lesson Transcript
Instructor: Betsy Chesnutt

Betsy teaches college physics, biology, and engineering and has a Ph.D. in Biomedical Engineering

Van de Graaff generators do more than just make your hair stand up! They use static electricity to produce very high voltages, which are used in all kinds of applications. In this lesson, learn how Van de Graaff generators are able to produce such high voltages!

Basics of Static Electricity

If you could shrink yourself until you were really, really tiny, you would find that everything is made out of atoms. Inside each atom are even smaller particles called electrons and protons, which each have an electric charge. Protons are in the nucleus of the atom and are positively charged, while electrons exist in a cloud around the nucleus and are negatively charged.

Electrons can be pretty easily removed from atoms because they're not tightly bound to the nucleus like protons are. When an object picks up extra electrons, then the whole object becomes negatively charged. If it loses electrons, then it has more protons than electrons, so it becomes positively charged.

Whether we're talking about individual electrons and protons or much larger charged objects, positive and negative charges interact with each other in very predictable ways. Objects that have the same type of charge, either both positive or both negative, will repel each other, while objects with different types of charges, one positive and one negative, attract each other. These interactions between positive and negative charges are known as static electricity.

That's all you need to know! This simple concept explains everything from how lightning forms to why your hair stands up and your sweater sticks to your jacket on a cold day. It also is the basis for a really cool electrical device, the Van de Graaff generator.

Van De Graaff Generators

A Van de Graaff generator uses static electricity and a moving belt to charge a large metal sphere to a very high voltage. You may have seen one in a science museum or maybe in your science class. If you put your hands on a Van de Graaff generator, it will make your hair stand up!

Why does this happen? The generator has a large charge on its surface, so when you touch it, you also pick up some of that charge. It passes into your hair, too, so each strand has the same charge. Remember what happens when things have the same charge? They repel! Because each strand of your hair has the same type of charge, the individual strands all try to get as far away from each other as possible.

Van de Graaff generators can also create lightning-like sparks that travel through the air. This happens if an object with an opposite charge is held near the generator. Remember that opposite charges attract each other, and the force of this attraction can be strong enough to allow charges to pass through the air, creating a spark.

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