AQA GCSE Combined Science (8464), Higher tier · Physics › Magnetism and electromagnetism › Permanent and induced magnetism, magnetic forces and fields
Practise Poles of a magnet. 11 exam-style questions on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
The poles of a magnet are the places where its magnetic forces are strongest. You need to describe how like and unlike poles affect each other, and the difference between a permanent magnet and an induced magnet. Expect 1 to 3 mark recall, 'describe' and 'explain' questions, often about magnets, nails or paper clips.
Grade by grade
What you need to be able to do, from the first marks up to the top grade.
3
State where a magnet's forces are strongestThe magnetic forces are strongest at the poles: the north (seeking) pole and the south (seeking) pole.
3
Predict attraction or repulsion between two polesLike poles (N and N, or S and S) repel; unlike poles (N and S) attract.
4
Identify magnetic forces as non-contact forcesMagnets attract or repel each other without touching, so these are non-contact forces.
5
Describe the difference between permanent and induced magnetsA permanent magnet produces its own magnetic field; an induced magnet only becomes a magnet when it is placed in a magnetic field.
6
Explain why induced magnetism always attractsThe end of the material nearest the magnet becomes the opposite pole to the magnet's pole, so there is always attraction.
7
Explain how to test for a magnetOnly repulsion proves an object is a permanent magnet, because a magnetic material is attracted to both poles.
Notes
Poles and forces
Every magnet has two poles: a north (seeking) pole and a south (seeking) pole.
The magnetic forces are strongest at the poles.
When two magnets are brought close together, they exert a force on each other.
Like poles repel (N and N, or S and S). Unlike poles attract (N and S).
The magnets do not have to touch, so magnetic attraction and repulsion are non-contact forces.
The forces get weaker as the magnets are moved further apart.
Permanent and induced magnets
A permanent magnet produces its own magnetic field all the time, e.g. a steel bar magnet.
An induced magnet is a material that becomes a magnet when it is placed in a magnetic field, e.g. an iron nail held near a bar magnet.
Induced magnetism always causes a force of attraction.
This is because the end of the material nearest the magnet becomes the opposite pole: a nail near a north pole gets a south pole at its near end. grade 6+
When it is taken out of the magnetic field, an induced magnet loses most or all of its magnetism quickly.
Iron loses its induced magnetism quickly, which is why it is used for the core of an electromagnet that must switch off. Steel keeps its magnetism, so it is used for permanent magnets.
Testing for a magnet grade 7+
A magnetic material (iron, steel, cobalt or nickel) is attracted to either pole of a magnet, because the magnet induces magnetism in it.
So attraction does not prove that an object is a magnet.
Only repulsion proves it: bring each end of the object up to one pole of a known magnet. If one end is repelled, the object is a permanent magnet.
Cheatsheet
Poles: north (seeking) and south (seeking); forces are strongest at the poles
Like poles repel; unlike poles attract
Magnetic attraction and repulsion are non-contact forces
Permanent magnet: produces its own magnetic field
Induced magnet: becomes a magnet only when placed in a magnetic field
Induced magnetism always causes attraction
An induced magnet loses most or all of its magnetism quickly when removed from the field
Magnetic materials: iron, steel, cobalt and nickel
Only repulsion proves an object is a permanent magnet grade 7+
How to answer each type of question
State whether two magnets attract or repel
1 to 2 marks3
Find which two poles are facing each other.
Like poles repel; unlike poles attract.
If one object is only a magnetic material (not a magnet), the answer is always attract.
Example. Two bar magnets, A and B, lie end to end on a table. The north pole of magnet A faces the south pole of magnet B. (a) State whether the magnets attract or repel each other. (b) Magnet B is turned round, so that its north pole faces magnet A. State whether the magnets now attract or repel.
Show the model answer
(a) Attract (1) (b) Repel (1)
Describe the difference between a permanent and an induced magnet
2 to 4 marks5
Say what a permanent magnet does: it produces its own magnetic field.
Say what an induced magnet is: a material that only becomes a magnet when it is in a magnetic field.
If asked what happens when the magnet is taken away, say the induced magnet loses (most of) its magnetism quickly.
Example. A bar magnet picks up an iron nail. A second iron nail hangs from the bottom of the first nail. (a) The first nail is an induced magnet. Describe the difference between a permanent magnet and an induced magnet. [2 marks] (b) The bar magnet is carefully pulled away from the top of the first nail. Suggest what happens to the second nail. Give a reason for your answer. [2 marks]
Show the model answer
(a) A permanent magnet produces its own magnetic field (1). An induced magnet only becomes a magnet when it is placed in a magnetic field (1). (b) The second nail falls off (1) because the first nail loses (most of) its magnetism quickly when it is no longer in the magnetic field (1).
Explain how to show whether an object is a permanent magnet
2 to 3 marks7
Explain why attraction is not enough: a magnetic material is attracted to either pole.
Describe the test: bring each end of the object up to the same pole of a known magnet.
Give the conclusion: repulsion means it is a permanent magnet.
Example. A student has a metal rod. She says: 'The rod is attracted to the north pole of my bar magnet, so the rod must be a magnet.' Explain why she could be wrong, and describe a test that would show whether the rod is a permanent magnet. [3 marks]
Show the model answer
The rod could be a magnetic material, which is attracted to either pole because magnetism is induced in it (1). Bring each end of the rod in turn up to the north pole of the bar magnet (1). If one end is repelled, the rod is a permanent magnet (1).
Shortcuts and memory tricks
Unlike poles attract, like poles repel: the same rule as for positive and negative electric charges.
'Attraction can fool you, repulsion proves it': only repulsion shows an object is a magnet.
ICoNS: Iron, Cobalt, Nickel, Steel are the magnetic materials.
'Induced' means 'in a field': an induced magnet is only a magnet while it is in a magnetic field.
Where marks are lost
Saying an induced magnet can repel a magnet: induced magnetism always causes attraction.
Saying all metals are magnetic: copper, aluminium, gold and silver are not. Only iron, steel, cobalt and nickel are.
Saying the forces are strongest in the middle of a magnet: they are strongest at the poles.
Using attraction as proof that an object is a magnet.
Calling the poles 'positive' and 'negative': magnetic poles are north and south.
Exam technique
Use the words 'attract' and 'repel'. Vague words such as 'react' or 'affect each other' do not get the mark.
In 'describe the difference' questions, write about both types of magnet, not just one.
If a question says an object becomes magnetised only while it is near a magnet, it is describing an induced magnet.
Quick recall
Cover the answers and test yourself. The app has these as flashcards that come back just before you'd forget them.
A student holds two bar magnets close to each other. Where are the magnetic forces of a bar magnet strongest?
At the poles
Two magnets exert forces on each other without touching. What type of force is this?
A non-contact force
Give one everyday object that uses a permanent magnet.
A fridge magnet (or any similar example).
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy4 marks
A student holds two bar magnets close to each other.
(a) The north pole of one magnet is brought close to the north pole of the other magnet. What happens? Tick (✓) one box.[1]
The magnets attract each other.
The magnets repel each other.
There is no force between the magnets.
(b) The force between the two magnets is an example of which type of force? Tick (✓) one box.[1]
Contact force
Friction
Non-contact force
Tension
(c) Where are the magnetic forces of a bar magnet strongest?[1]
(d) Name one magnetic material.[1]
Show the answer and mark scheme
(a)Answer: The magnets repel each other.
(b)Answer: Non-contact force
(c)Answer: At the poles
at the poles / at the ends
(d)Answer: Iron (or steel, cobalt or nickel)
iron / steel / cobalt / nickel
Question 2Medium7 marks
A student hangs a small iron nail from the north pole of a bar magnet. A second nail is then hung from the bottom of the first nail, and a third nail from the bottom of the second, forming a chain.
(a) Explain why the first nail is attracted to the magnet.[2]
(b) Explain why the second nail is attracted to the first nail.[1]
(c) The student carefully pulls the magnet away from the top nail. Describe and explain what happens to the chain of nails.[2]
(d) Describe the difference between a permanent magnet and an induced magnet.[2]
Show the answer and mark scheme
(a)Answer: The nail becomes an induced magnet, and induced magnetism always causes attraction.
the nail becomes an induced magnet (when it is in the magnetic field)
induced magnetism always causes a force of attraction
(b)Answer: The first nail has become a magnet and induces magnetism in the second nail.
the first nail is magnetised / is an induced magnet, so it induces magnetism in the second nail (which is attracted)
(c)Answer: The chain falls apart because the nails lose their induced magnetism quickly.
the nails fall apart / drop off
an induced magnet loses most or all of its magnetism quickly when it is removed from the magnetic field
(d)Answer: A permanent magnet has its own magnetic field; an induced magnet is only a magnet while it is in a magnetic field.
a permanent magnet produces its own magnetic field (all the time)
an induced magnet only becomes a magnet when it is placed in a magnetic field
Question 3Hard5 marks
A student holds the north pole of a bar magnet near one end of an unmagnetised iron rod. The rod is attracted to the magnet. The student then turns the magnet round, so that its south pole is near the same end of the rod. The rod is still attracted to the magnet.
(a) Explain why the iron rod is attracted to the magnet in both cases.[3]
(b) The student takes the bar magnet away. Describe and explain what happens to the magnetism of the iron rod.[2]
Show the answer and mark scheme
(a)Answer: The rod becomes an induced magnet whose nearer end is always the opposite pole to the magnet's pole, and unlike poles attract — so induced magnetism always gives attraction.
the rod becomes an induced magnet when it is placed in the magnetic field of the bar magnet
the end of the rod nearest the magnet becomes the opposite pole to the pole held near it (a south pole near the magnet's north pole, a north pole near its south pole)
unlike poles attract, so induced magnetism always causes a force of attraction
(b)Answer: It quickly loses most or all of its magnetism, because an induced magnet is only magnetised while it is in a magnetic field.
the rod loses most or all of its magnetism (quickly)
because it was only an induced magnet: it is magnetised only while it is in a magnetic field