Magnetism

What poles attract?

S and N.

What poles repel?

S and S, N and N.

Name a magnetic material.

Iron, steel, cobalt, nickel, and some rare earth metals like neodymium.

What direction do magnetic field lines go?

North to south.

What is induced magnetism?

When a non-magnetic object becomes a magnet when attached to one.

When will a wire have a magnetic field round it?

When it has a current running through it.

What is a permanent magnet?

An object that always has a magnetic field around it.

What is a temporary magnet?

An object that only has induced magnetism from actual magnetic objects.

How do you increase the strength of an electromagnet?

Add more coils or increase the current.

What is the motor effect?

When any wire carrying a current can experience a force near a magnetic field.

What do transformers do?

They change the voltage of an electrical supply.

What is a transformer made up of?

Two coils wound onto an iron core.

Why is the power supplied to the primary coil and the power supplied away from the secondary coil equal?

Energy can’t be created or destroyed.

What do pylons do?

They transport energy to factories, homes, shops and offices across the country through extremely long overhead copper wires.

How do you prevent energy being wasted in wires?

By decreasing the current so less energy is wasted through heating.

What is a step-up transformer?

A transformer that increases voltage and decreases current simultaneously.

What is a step-down transformer?

A transformer that lowers voltage and increases current simultaneously.

What is a solenoid?

A coil of wire with electricity flowing in it.

How could the magnetic field in a solenoid be made stronger?

Add more turns to the coil.

How can iron filings be used to show the shape of an object’s magnetic field?

Put the magnetic object underneath the iron filings, and they will move into the shape of the magnetic field.

What are uniform magnetic fields like?

They are straight lines between two magnets.

What is the strongest place on a magnetic field?

Where the lines are the closest.

Demonstrate Fleming’s left-hand rule.

Thumb = force.

Index finger = magnetic field

Middle finger = current

How do you use iron filings to find out the shape of a magnetic field?

Put the object under the iron filings and they will move in the shape of its magnetic field.