IGCSE Physics: Simple Phenomena of Magnetism Practice Questions
Like magnetic poles repel and unlike poles attract. A magnetic field is the region where a magnetic material experiences a force, and field lines are drawn from north to south with their spacing showing the strength of the field.
Sub-topic 4.1 of Cambridge IGCSE Physics 0625 is short but supplies the ideas used in the motor effect and electromagnetic induction. The one test examiners return to again and again is that only repulsion proves an object is a magnet. The questions below make that point directly.
What you need to know for Simple Phenomena of Magnetism
- Magnetic materialsIron, steel, cobalt and nickel are magnetic. Copper, aluminium, brass and plastic are not, even though copper and aluminium conduct electricity well.
- PolesLike poles repel, unlike poles attract. Repulsion is the only sure test that both objects are magnets, because a magnet attracts unmagnetised magnetic material as well.
- Induced magnetismAn unmagnetised magnetic material becomes a magnet when placed in a magnetic field or brought near a magnet. This is why a magnet picks up a chain of paper clips.
- Magnetic field linesDrawn from north to south outside the magnet, never crossing. Closer lines mean a stronger field, so the lines are most concentrated at the poles.
- Soft and hard magnetic materialsSoft iron magnetises and demagnetises easily, so it is used for electromagnet cores and transformer cores. Steel is hard, keeping its magnetism, so it is used for permanent magnets.
- ElectromagnetA coil of wire wound on a soft iron core. Its strength increases with the current, the number of turns and the use of a soft iron core, and it can be switched off.
IGCSE Physics Simple Phenomena of Magnetism questions and answers
4 exam-style questions written to the 0625 syllabus. Try each one on paper first, then open the worked answer to check your method against the marks.
A student has two identical looking steel bars. One is a magnet and one is not. Describe a test that proves which is the magnet, and explain why attraction alone is not sufficient.
Show the worked answer
- Bring one end of the first bar close to one end of the second bar and observe. Then turn one bar round and repeat.
- If repulsion is observed in either arrangement, both bars are magnets.
- If only attraction is observed however the bars are arranged, one bar is a magnet and the other is unmagnetised steel.
- Attraction alone is not sufficient because a magnet attracts unmagnetised magnetic material as well as the opposite pole of another magnet. Repulsion happens only between two like poles, so it can only occur if both objects are magnetised.
Describe the magnetic field around a bar magnet, stating the direction of the field lines and how the diagram shows where the field is strongest.
Show the worked answer
- The field lines emerge from the north pole and travel round to the south pole outside the magnet, forming closed loops.
- Arrows on the lines show the direction in which a free north pole would be pushed.
- The lines never cross one another, because the field can only have one direction at each point.
- Where the lines are closest together the field is strongest. This is at the poles, and the lines spread out and become more widely spaced further from the magnet, showing the field weakens with distance.
Explain why a magnet can pick up a chain of several paper clips hanging one below another.
Show the worked answer
- The first paper clip is placed in the magnet's field, so magnetism is induced in it and it becomes a temporary magnet.
- The induced pole nearest the magnet is opposite to the magnet's pole, so it is attracted and held.
- The far end of that clip becomes the opposite pole, which induces magnetism in the next clip and attracts it, and so on down the chain.
- The field weakens with distance, so the induced magnetism becomes weaker at each stage and the chain eventually cannot support another clip.
State two differences between a permanent magnet made of steel and an electromagnet, and give one situation where the electromagnet is the better choice.
Show the worked answer
- Difference 1: a permanent magnet is always magnetic, whereas an electromagnet is magnetic only while a current flows and can be switched off.
- Difference 2: the strength of an electromagnet can be varied by changing the current or the number of turns, while a permanent magnet's strength is fixed.
- A scrapyard crane needs to pick up scrap steel, move it, then release it on command.
- Only an electromagnet allows the load to be released by switching off the current, so it is the better choice.
Common mistakes in this topic
- Using attraction as proof that both objects are magnets.
- Drawing field lines that cross, or omitting the arrows.
- Assuming all metals are magnetic. Copper, aluminium and brass are not.
- Using steel for an electromagnet core. Steel keeps its magnetism, so the electromagnet would not switch off cleanly.
- Saying the field is uniform around a bar magnet. It is strongest at the poles and weakens with distance.
Exam tips
- In any test question about magnets, look for repulsion. It is the only conclusive result.
- Draw field lines with a ruler and a smooth curve, always with arrowheads and never crossing.
- Learn soft iron for temporary magnetism and steel for permanent magnetism, then apply it to cores and magnets.
- For a plotting compass question, say that the compass needle aligns with the field at each point.
- Any electromagnet strength question has three answers: increase the current, increase the number of turns, use a soft iron core.
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Simple Phenomena of Magnetism FAQs
How can I tell whether an object is a magnet?
Test for repulsion. A magnet attracts unmagnetised magnetic materials such as iron and steel as well as the opposite pole of another magnet, so attraction proves nothing. Repulsion occurs only between two like poles, so it proves that both objects are magnetised.
Which materials are magnetic?
Iron, steel, cobalt and nickel are magnetic. Most other metals, including copper, aluminium and brass, are not, even though several of them are excellent electrical conductors. Non-metals such as plastic and wood are never magnetic.
How are magnetic field lines drawn?
They run from the north pole to the south pole outside the magnet, with arrows showing the direction a free north pole would move. They never cross. Where the lines are closest together the field is strongest, which is why they are most tightly packed at the poles.
What is the difference between soft iron and steel in magnetism?
Soft iron magnetises and demagnetises easily, so it is used for electromagnet and transformer cores where the magnetism must switch off. Steel is magnetically hard and retains its magnetism, so it is used to make permanent magnets such as compass needles and fridge magnets.
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Written to the published Cambridge IGCSE Physics (0625) syllabus. Check your school entry code and syllabus year, because Core and Extended candidates are assessed on different content. Last reviewed 2026-08-12.