AQA GCSE Physics Foundation (8463), Foundation tier · Magnetism and electromagnetism › Permanent and induced magnetism
Practise Magnetic fields. 7 exam-style questions on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
A magnetic field is the region around a magnet where another magnet or a magnetic material feels a force. You need to draw the field of a bar magnet, describe how to plot it with a compass, and explain why a compass is evidence that the Earth's core is magnetic. Expect drawing questions, 'describe how' method questions and short explanations.
Key facts
Magnetic field: region where another magnet or a magnetic material feels a force
Magnetic materials: iron, steel, cobalt, nickel (always attracted)
Field direction = direction of the force on a north pole placed there
Field lines go from N to S outside the magnet; always draw arrows
Closer field lines = stronger field; strongest at the poles
Field strength decreases with distance from the magnet
Compass = small bar magnet that lines up with the field
A compass points north with no magnet nearby, so the Earth has a magnetic field (magnetic core)
Notes
What a magnetic field is
A magnetic field is the region around a magnet where a force acts on another magnet or on a magnetic material.
The magnetic materials are iron, steel, cobalt and nickel. The force between a magnet and a magnetic material is always attraction.
The field is strongest at the poles. It gets weaker as the distance from the magnet increases.
Drawing field lines
diagram
Outside a magnet, field lines go from the north pole to the south pole. Always add arrows.
The closer together the lines, the stronger the field. Draw them closest together at the poles and further apart away from the magnet.
Field lines never cross.
Field lines go from N to S, never cross, and are closest together at the poles, where the field is strongest.
Between a north pole and a south pole facing each other, the lines are straight, parallel and equally spaced. This is a uniform field (the same strength everywhere).
Between facing N and S poles the field is uniform.
Plotting a field with a compass
diagram
A plotting compass contains a small bar magnet (the needle). The needle lines up with the magnetic field, and its north end points in the direction of the field.
Put the bar magnet on a sheet of paper and draw round it.
Place the compass near the north pole. Mark a dot at the end the needle points to.
Move the compass so the tail of the needle is over the dot, then mark a new dot. Repeat until you reach the south pole.
Join the dots with a smooth curve and add an arrow in the direction the needle pointed. Repeat from several starting points.
Each dot is marked at the tip of the needle. Move the compass so its tail is on the last dot, and repeat. The red north end of the needle shows the field direction.
The Earth's magnetic field
diagram
A compass needle points north even when there is no magnet near it: it lines up with the Earth's magnetic field.
This is evidence that the Earth has a magnetic field, so the Earth's core must be magnetic. The field has a similar shape to that of a bar magnet.
The Earth's field is like the field of a bar magnet inside it. The magnet's south pole is near the geographic North Pole, so the north end of a compass points north.
How to answer each type of question
Draw the magnetic field pattern of a bar magnet
2 to 3 marksGrade 4
Draw several continuous curved lines from one pole to the other, on both sides of the magnet.
Put an arrow on every line, pointing from N to S.
Draw the lines closest together near the poles, and make sure no lines cross.
Example. Sketch a bar magnet, label its poles, and draw the magnetic field pattern around it. Show the direction of the field. [3 marks]
Show the model answerHide the model answer
A sketch like this scores all 3 marks. Several continuous curved lines from one pole to the other on both sides of the magnet, not crossing (1). Arrows on the lines pointing from the north pole to the south pole (1). Lines closer together near the poles than further from the magnet (1).
Describe how to plot a magnetic field using a compass
3 to 4 marksGrade 5
Start with the set-up: magnet on paper, outline drawn round it.
Describe marking where the needle points, then moving the compass along to the dot.
Say you repeat until you reach the other pole, then join the dots.
Finish with arrows and repeating from different starting points.
Example. Describe how a student could use a plotting compass to find the shape of the magnetic field around a bar magnet. [4 marks]
Show the model answerHide the model answer
Place the magnet on a sheet of paper and draw round it (1). Put the compass near one pole and mark a dot where the needle points (1). Move the compass so the tail of the needle is on the dot, mark the next dot, and repeat until the compass reaches the other pole (1). Join the dots to make a field line, add an arrow in the direction the needle points, and repeat from several different starting points (1).
Don’t lose marks
Forgetting the arrows, or drawing them from S to N.
Drawing field lines that cross or touch each other.
Drawing the lines evenly spaced all the way round: they must be closest together at the poles.
Plotting only one line: the method needs several lines from different starting points.
In the Earth question, not saying that the compass needle is a magnet that lines up with a magnetic field.
More tips
Memory tricks
'North Out, South In': field lines leave the north pole and go into the south pole.
Crowded lines mean a strong field; spread-out lines mean a weak field.
The north end of a compass needle always points along the field lines, so it gives you the arrow direction.
ICoNS: Iron, Cobalt, Nickel, Steel are the magnetic materials.
Exam technique
Draw field lines as smooth curves with a sharp pencil: examiners check the shape, the arrows and the spacing.
Write method answers as steps in order, and include marking the needle position and moving the compass on.
When a question asks about a 'field', use the words 'magnetic field' in your answer, not just 'magnetism'.
What each grade needs
What you need to be able to do, from the first marks up to the top grade.
Grade 3
Name the four magnetic materialsIron, steel, cobalt and nickel are always attracted by a magnet.
Grade 4
Draw the field pattern of a bar magnetCurved lines from the north pole to the south pole, with arrows, closest together at the poles.
Grade 5
Plot a magnetic field using a compassMark where the compass needle points, move the compass on, repeat, then join the dots from N to S.
Grade 5
State how field strength depends on distanceThe field is strongest at the poles and gets weaker further from the magnet.
Quick recall
Cover the answers and test yourself. The app has these as flashcards that come back just before you'd forget them.
State the direction of the magnetic field lines outside a bar magnet.
From the north pole to the south pole.
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy5 marks
(a) Which two metals are magnetic materials? Tick (✓) two boxes.[2]
Aluminium
Cobalt
Copper
Nickel
Zinc
(b) In which direction do magnetic field lines point outside a bar magnet? Tick (✓) one box.[1]
From the north pole to the south pole
From the south pole to the north pole
Towards both poles
Away from both poles
(c) What is meant by the magnetic field of a magnet?[1]
(d) A plotting compass is placed on a table, far away from any magnets. In which direction does the north end of its needle point?[1]
Show the answer and mark scheme
(a)Answer: Cobalt; Nickel
(b)Answer: From the north pole to the south pole
(c)Answer: The region around a magnet where another magnet or a magnetic material experiences a force.
the region around a magnet where a force acts on another magnet or on a magnetic material
(d)Answer: North (along the Earth’s magnetic field)
north / along the Earth’s magnetic field
Question 2Medium6 marks
A plotting compass is placed on a table, far away from any magnets. The compass needle points north.
(a) Explain why the compass needle points north.[2]
(b) Explain how the behaviour of compasses provides evidence that the Earth’s core is magnetic.[2]
(c) The compass is moved close to the north pole of a bar magnet. Describe and explain what happens to the compass needle.[2]
Show the answer and mark scheme
(a)Answer: The needle is a small magnet that lines up with the Earth’s magnetic field.
the compass needle is a small (bar) magnet
it lines up with / points in the direction of the Earth’s magnetic field
(b)Answer: Compasses everywhere line up with a field shaped like that of a bar magnet, so the Earth itself must be magnetic inside.
compasses all over the Earth line up with a magnetic field (with a pattern like that of a huge bar magnet)
so the Earth must produce its own magnetic field, which comes from inside the Earth (its core)
(c)Answer: The north end of the needle points away from the magnet, because near the magnet its field is much stronger than the Earth’s and points away from its north pole.
the needle turns so that its north end points away from the magnet’s north pole (its south end points towards it)
close to the magnet, the magnet’s field is much stronger than the Earth’s field / the needle points along the magnet’s field (which points away from a north pole)