Physics - Magnetism

What is magnetism?

A non-contact force, like gravity, but unlike friction.

What is a magnetic field?

The region of space around a magnet where another magnet will feel a force.

What are the three rules for drawing magnetic fields?

Field lines cannot intersect each other.

The denser the field lines, the stronger the field.

The field lines’ arrows point away from north bar / towards the south bar of the magnet.

Where is the field strongest and weakest?

The field is strongest when it is very close to the poles. It is weakest when it is far from the poles.

What is the magnetic field of a normal bar magnet?

Is Geographic South on Earth the Magnetic North or the Magnetic South?

Magnetic North - they are opposite. Geo North will be Mag South.

What does Earth’s magnetic field look like?

When like poles are put next to each other, will they repel or attract? What does their magnetic field look like?

Repel.

When opposite poles are put next to each other, do they repel or attract? What is their magnetic field?

Attract.

What does a uniform field look like?

What should you always try to do when drawing a uniform field?

Try to make the size of the gaps between the field lines the same.

What are permanent magnets’ domains like?

They are aligned.

Does a non-magnetic material have domains?

No, they don’t.

A magnetic material has something domains. What is it?

Random domains.

What is another word for random domains?

The domains are unaligned.

If you put a magnet near a magnetic material, their domains will do what?

They will align. This means the material has been magnetised.

What is a soft magnetic material?

A magnetic material that when you take a magnet away from it, their domains unalign again. This is called demagnetisation.

What are some examples of soft magnetic materials?

Iron, cobalt, nickel.

What is a hard magnetic material?

A magnetic material that when you take a magnet away from it, it’s domains remain permanently magnetised (aligned).

What are some examples of hard magnetic materials?

Steel and alloys.

What is the magnetic field for a wire going through a paper?

The field lines are in what circles?

Concentric circles.

The field gets something as you move further away.

Weaker.

What does the dot in the middle mean?

The current flows out of the page.

What are electromagnets use electric current to do what?

To make magnetic fields.

What materials are used for electromagnets?

Soft magnetic materials, usually iron.

What are the three ways to increase the strength of an electromagnet?

Increase current (voltage).

Increase number of loops of wire on coil.

Change the magnetic core to a material more magnetic.