Magnetism: Page 66

QUESTION: Can any metal become a magnet?

OBJECTIVE: SWBAT explain why some metals have magnetic properties.

VOCABULARY: magnet magnetic polemagnetic field magnetic domain

Magnetism

Write these questions onto page 66

1. Draw the magnetic domain of a magnet.

2. What are some common places magnets are used?

The First Magnet

2,ooo years ago a rock with a very special property was discovered in Greece, near the town of Magnesia. This is how magnets got their name.

The mineral name of this rock is magnetite. It is also called loadstone.

Properties of Magnets

This rock would attract objects made of iron. It would also attract and repel other magnetic rocks.

About a 1,000 years ago it was discovered that this rock would point North if is was allowed to swing freely. This was the first compass.

Magnetic Poles

Any magnet, no matter what its shape , has two ends, called magnetic poles.

The end that points north is called the north pole. The end that points south is the south pole.

Opposite poles attract one another, while like poles repel.

Why Do Magnets Point North?

Magnets point north because the Earth is a gigantic magnet with a north and a south pole.

Why is the Earth a magnet?

Magnetic Fields

The area around a magnet where attraction or repulsion occurs is called the magnetic field.

Strong magnets will have a larger magnetic field than weak magnets..

Why are Some Metals Magnetic?

All matter including magnets are made up of atoms. These atoms contain spinning electrons.

As an electron spins it creates a very small magnetic field. In most matter the electrons spin in different directions. This causes the magnetic fields to point in different directions cancelling each other out.

Why are Some Metals Magnetic?

Magnets have electrons that all spin in the same direction causing one big magnetic field.

A group of atoms that have their electrons spinning in the same direction is called a magnetic domain.

Making a Magnet

If a piece of iron is rubbed many times in the same direction against a strong magnet, the domains of that piece of iron will line up causing the iron to become magnetized.

Breaking a Magnet

What will happen if you break a magnet in half? Will it still have a north and south pole, or will it have two poles the same?

In What Machines Are Magnets Found?

Magnets are found in all machines having motors. They are also found in computers, televisions, cameras, phones, video games, audio speakers and hundreds of other machines.

Magnetism: page 66

Check that the answers to these questions are in your notes.

1. Draw the magnetic domain of a magnet.

2. What are some common places magnets are used?

VOCABULARY

Magnet-any material that attracts iron.

Magnetic pole-the ends of a magnet.

Magnetic field-an area around a magnet where the magnetic force exists.

Magnetic domain-an area where the magnetic field of all atoms is lined up in the same direction.