Page 148 - Knowledge Organiser Yr8 24-25

Knowledge Base: Science 8.10 Force Fields Year 8
5. Magnetic Interactions
5.1
What will happen if two north poles are brought together?
They will repel.
5.2
What will happen if two south poles are brought together?
They will repel.
5.3
What will happen if a north and a south pole are brought together?
They will attract.
5.4
What happens if a permanent bar magnet is split in half?
Both halves become new bar magnets with their own north and south poles.
7. Electromagnets
7.1
What is produced around a current carrying wire?
A magnetic field.
7.2
How can you increase the strength of the magnetic field around a wire?
Create a coil.
7.3 What is an electromagnet? A coil of wire with an iron core.
7.4
What happens to the magnetic field around a wire when the current is not flowing?
There is no magnetic field.
7.5
How can you increase the strength of an electromagnet?
1. Increase the number of turns in the wire.
2. Increase the current flowing through the wire.
7.6
Why are electromagnets sometimes used instead of a permanent magnet?
1. Electromagnets can be turned on and off. 2. Electromagnets are usually stronger.
6. Earth
6.1
What is the Earth’s core made of?
Iron.
6.2
What does the magnetic field of the Earth look like?
It looks like the magnetic field that is created around a bar magnet.
6.3
Where would you find the Earth’s magnetic south pole?
At the Earth’s geographic north pole.
6.4
What way does a compass always point?
Towards the Earth’s geographic north pole.
6.5
Why does a compass point towards the geographic north pole of Earth?
The compass needle is a small bar magnet. The point is the north pole.
This will be attracted to the Earth’s magnetic south pole which is found at the Earth’s geographic north pole.
8. Using Electromagnets
8.1
Give three uses of electromagnets.
1. The Maglev train
2. Sorting metal in scrap yards 3. The school bell
8.2
Some appliances have spinning components. What causes these components to spin?
A motor
8.3
What is the motor effect?
When a DC current is passed through a wire placed in a magnetic field, it will cause the wire to move.
8.4
How does a motor work?
• Both the permanent magnet and the current-carrying wire have a magnetic field around them.
• The permanent magnet and the wire exert a force on each other.
• This makes the coil spin.
148