This practical can be conducted as a very simple introduction to electrostatics. It can be conducted as a class practical very easily or can be demonstrated by a teacher.

Equipment required (per set):

• Thin fishing line
• Two balloons
• Duster
• Metre rule
• Clamp and stand

The two balloons are inflated and each tied to a length of fishing line. The free end of each line is tied to one end of a metre rule which is clamped securely to a stand. The two balloons should hang freely from the metre rule, touching each other at the same point.

If the duster is rubbed on each of the balloons and they are left to hang they will repel each other. This is because they have the same charge.

If the balloons are rubbed against one another, they will take on a different charge and will attract each other.

This principle forms the basis of electrostatics and can be applied to other lessons involving the Van De Graff generator or the Wimshurst machine.

The fishing line is used because the nylon will itself not take on a charge unlike some other threads. It is important that the balloons are not hanging near the clamp stand or near any other metalwork, which is why the metre rule is used to distance them.