Page 147 - Science Coursebook

10.3 Electrons on the move

Explaining why neutral objects are attracted by charged objects
If you rub a balloon on a cloth, it will become charged. If you hold the charged
balloon near a scrap of paper, it will attract the paper.
The paper is not charged. So why is it attracted?

The reason is that the paper contains electrons. (Everything that is made of atoms
contains electrons.) If the balloon has a positive charge, it attracts the electrons in the
paper and so the paper feels a force towards the balloon.
Understanding how electrons behave is the key to understanding electricity.
J. J. Thomson discovered electrons in 1897, so it is not surprising that scientists did not
really understand what was going on before then.

Question

4 If you put two electrons next to each other, would they attract or repel each
other? Explain your answer.

Activity 10.3

Everything's electric!

It is important to understand that
everything is made of atoms. Atoms
have electrons and so everything
is electric.
Use thread to hang different items, so

that they are free to turn. Make sure
that they are not moving.
Charge a plastic rod by rubbing it
with a cloth. Bring the charged rod
close to one end of the hanging item. Even a pepper (capsicum) contains electrons and can be
Can you observe attraction? attracted by a charged rod.

Summary
• Objects become charged when electrons are rubbed from one
object to another.
• The object which gains electrons has a negative charge; the object that
loses electrons has a positive charge.

10 Electricity 145