Magnets & Magnetism

What do all magnets have?

Two poles - north and south

What is a magnetic field?

A region surrounding a magnet where other magnets or magnetic materials experience a non-contact force.

What kind of force is a magnetic force?

Non-contact.

Name some magnetic materials:

Iron, steel(alloy), cobalt and nickel

In what direction do magnetic field lines go?

North to south.

What do magnetic field lines show?

Which way a force would act on a north pole if it was put at that point in the field.

The closer together the lines are…

The stronger the magnetic field.

The further away from a magnet you get…

the weaker the magnetic field.

Where is the magnetic field strongest?

At the poles.

At which part of a magnet are the magnetic forces strongest?

At the poles of the magnet.

What is the force between a magnet and a magnetic material?

Always attractive.

What happens when two magnets are brought close to each other?

They exert a force on each other.

Two like poles brought close to eachother will…

repel each other.

Two unlike poles brought close to eachother will…

attract each other.

What do compasses show the direction of?

Magnetic fields.

What is inside a compass?

A tiny bar magnet (needle) that points in the direction of the Earth’s magnetic field.

What is the north pole of this magnet (needle) attracted to?

The south pole of any other magnet that is near.

How can you investigate the shape and direction of a Magnetic field?

1. Place the magnet on top of a piece of paper and draw a dot at one end of the magnet near its corner

2. Place a plotting compass next to the dot so one end of the needle of the compass points away from the dot, use a pencil to draw a new dot at the other side of the compass needle

3. Move the compass so that it points away from the new dot and repeat the process above

4. Keep repeating the previous process until there is a chain of dots going from one end of the magnet to the other, then remove the compass and link the dots using a smooth curve - this will be the magnetic field line

5. Repeat whole process several times to create several other magnetic field lines

What are the 2 types of magnet?

Permanent magnets and induced magnets

What is the difference between a permanent magnet and an induced magnet?

A permanent magnet produces its own magnetic field. Whereas, induced magnets are magnetic materials that turn into magnets/ become magnetic when placed in a magnetic field.

The force between permanent and induced magnets is always….

Attractive.

What happens when an induced magnet is removed from a magnetic field?

The induced magnet loses most or all of its magnetism.

What is produced when current flows through a conducting wire?

A magnetic field is produced around the wire.

What is the field made up of?

Concentric circles perpendicular to the wire.

What does a circular field pattern indicate?

That the magnetic field around a current-carrying wire has no poles.

What determines the strength of the magnetic field around a current-carrying wire?

• The magnitude of the current flowing through the wire

• The distance from the wire

The right-hand thumb rule

Using your right hand, point your thumb in the direction of current and curl your fingers. The direction of your curled fingers is the direction of the field.

Explain how the behaviour of a magnetic compass is related to evidence that the core of the Earth must be magnetic?

In the absence of any magnet or magnetic materials a magnetic compass will always point north - this is evidence that the core of the Earth is magnetic and creates its own magnetic field.