Magnets and magnetic fields Cambridge IGCSE Co-ordinated Sciences (Double Award) revision
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In plain words
A magnet has two ends, called poles: north and south. Two the same push apart; two different pull together. Around every magnet is a field: the region where it can pull on magnetic materials. Only a few materials are magnetic: iron, steel, nickel and cobalt.
Three things to know
- Like poles repel, unlike poles attract. Magnetic materials (iron, steel, nickel, cobalt) are attracted to both poles.
- Magnetic field lines run from north to south outside a magnet. Where they are closest together the field is strongest.
- Soft iron is easy to magnetise and loses its magnetism easily (temporary magnets, electromagnet cores). Steel is harder to magnetise but keeps it (permanent magnets).
Tips and tricks
- Field lines go from north to south, never cross, and are closest together where the field is strongest. Put arrows on them.
- Being attracted doesn't prove something is a magnet (a plain iron nail is attracted too). Only repulsion does.
It lands in your notebook with its questions as flashcards.
Magnets and magnetic fields: 6 questions and answers
These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.
Which of these is a magnetic material?
Iron, steel, nickel and cobalt are the common magnetic materials.
In which direction do magnetic field lines point outside a bar magnet?
By convention field lines leave the north pole and enter the south.
What is the only sure test that a piece of metal is a magnet?
Only two magnets can repel each other.
Where is the field of a bar magnet strongest?
The field lines are closest together at the poles.
Why is steel used for permanent magnets?
Steel is magnetically hard.
Two magnets are placed with south poles facing. What happens?
Like poles repel.
Quiz
6 questions
Tap an answer and you’ll see straight away whether it’s right, and why.
Worksheet
4 questions, 8 marks. Write your answers on paper, then check them.
Magnets and magnetic fields
Cambridge IGCSE Co-ordinated Sciences (Double Award) 0654 · 8 marks · papermunch.org
Name ______________________________ Date ______________
State what happens when (a) two north poles and (b) a north and a south pole are brought together.[2]
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(a) They repel. (b) They attract.
Describe how to plot the magnetic field around a bar magnet using a plotting compass.[2]
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Put the compass near a pole and mark where the needle points. Move the compass so its tail is on the mark, and repeat. Join the dots.
Explain why the core of an electromagnet is made of soft iron and not steel.[2]
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Soft iron loses its magnetism as soon as the current is switched off; steel would stay magnetised.
An unmarked metal bar is attracted to both poles of a magnet. State what this tells you about the bar.[2]
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It is a magnetic material but not itself a magnet (a magnet would be repelled by one of the poles).
Answers: Magnets and magnetic fields
- 1. (a) They repel. (b) They attract.
- 2. Put the compass near a pole and mark where the needle points. Move the compass so its tail is on the mark, and repeat. Join the dots.
- 3. Soft iron loses its magnetism as soon as the current is switched off; steel would stay magnetised.
- 4. It is a magnetic material but not itself a magnet (a magnet would be repelled by one of the poles).