Unit 3 - (Magnestism) Electromagnetism

Question 1

What are the poles of magnet in terms of magnetism

Answer 1

The parts of the magnet where the magnetism Is the strongest

Question 2

What is a magnetic field?

Answer 2

Is the space around a magnet where it’s magnetic force acts

Question 3

What do the lines of magnetic force show?

Answer 3

The shape of the field

Question 4

Which metal alloys will magnets attract to?

Answer 4

Magnets will ONLY attract to metal alloys which contain: -iron -cobalt -nickel

Question 5

What is the end of the magnet called which always points north?

Answer 5

The North-seeking pole

Question 6

What is electromagnetism?

Answer 6

Magnetism produced by electric currents

Question 7

What is an electromagnet?

Answer 7

A magnet whose magnetic field can be turned on and off with an electric current

Question 8

Advantages of electromagnets compared with normal magnets?

Answer 8

Can switch them off Can control their strength

Question 9

What is the composition of an electromagnet?

Answer 9

A solenoid (coil of wire) around an iron core

Question 10

How to make the magnetic field around an electromagnet stronger?

Answer 10

1. More turns in the coil
2. Use a larger current
3. Put an iron core in the solenoid (compared to eg plastic) 4. Make the turns tighter

Question 11

What happen if you freely suspend a magnet?

Answer 11

It will always come to rest on the north/south line of the Earth

Question 12

What happens when a current flows through a wire?

Answer 12

A magnetic field is created around the wire

Question 13

What is a magnetic field made up from?

Answer 13

Concentric circles with the wire in the centre

Question 14

What is electromagnetic induction?

Answer 14

The creation of a pd (voltage) across a conductor which is experiencing a change in magnetic field

Question 15

how can you do electromagnetic iduction?

Answer 15

By moving a magnet in a coil of wire or moving an electrical conductor in a magnetic field (‘cutting’ the magnetic field lines)

Question 16

What happens t the pd if you move the magnet in the opposite direction?

Answer 16

It The pd/current will be reversed too

Question 17

What happens to the pd if the polarity of the magnet is reversed?

Answer 17

It will be reversed too

Question 18

How do Dynamos work?

Answer 18

The cog wheel at the top is positioned so that it touched one of the wheels. As the wheels move rounds, it turns the cog which it attatched to the magnet. This creates an AC current to power the lights