Page 143 - Science Coursebook

10.1 Static electricity

Activity 10.1B
Observing electrical repulsion

SE The diagram shows one way to
investigate the force of one charged
object on another. A plastic rod hangs
from a thread so that it is free to turn
round. The rod is charged by rubbing
it with a cloth.
A second rod, made of the same
plastic, is also charged by rubbing it.
It is brought close to one end of the Two charged plastic rods – what
hanging rod. happens when the end of one rod is
brought close to the end of the other?
Try this. What do you observe?
Investigate what happens if you use

two rods made of different types
of plastic.

Attraction and repulsion
The experiments in this topic show that objects with an electric charge can attract
or repel other objects. This is rather like what you learnt about magnets in Unit 13 of
Stage 8. However, it is important to realise that the electric force caused by a charged
object is not the same as the magnetic force between magnets.
In the next topic, we will look at how scientists have learnt to explain
static electricity.

Questions
2 What are the rules of attraction and repulsion for magnetic poles?

SE 3 How could you test whether a plastic rod that has been given an electric
charge would attract or repel a magnet? Describe your method and include a
diagram. What result would you expect to observe?

Summary
• Objects can be given an electric charge by rubbing them.
• Electrically charged objects can produce a force of attraction
or repulsion.

10 Electricity 141