Repulsion is the only reliable test for a magnet. Attraction can come from a magnet or from unmagnetised iron, so on its own it proves nothing. This lesson is about reading and explaining results, not about how to set up equipment.
It appears in magnetism and fields as “what does this result show?” and “which bar is a magnet?” questions. The practical side is handled by your school under its own safety rules.
What can each result tell me?
Suppose a bar is brought near a known magnet, one end at a time, and you record what happens.
| Observation | What it shows |
|---|---|
| One end repels the north pole, the other end attracts it | The bar is a magnet |
| Both ends attract the same pole | The bar is an unmagnetised magnetic material (iron or steel), by induction |
| Neither end is attracted or repelled | The bar is not magnetic (for example plastic or copper) |
Only the first row needs a magnet in the bar. The second row is the trap: a magnet attracts iron whichever pole it uses.
How do I write the conclusion?
Use three parts: observation, meaning, reason. For example: “One end repelled the north pole, so the bar is a magnet, because only a magnet can repel.”
Quote the result that supports your claim. If two results disagree, say which is reliable.
Worked example
A class tests four bars, P, Q, R and S. Each end is brought near the north pole of a known magnet. (Invented data.)
| Bar | End 1 | End 2 |
|---|---|---|
| P | repelled | attracted |
| Q | attracted | attracted |
| R | no effect | no effect |
| S | attracted | attracted |
Later, both Q and S are stroked with a strong magnet in the same direction and the strong magnet is then taken away. Q now holds five pins, and S holds none.
Step 1, bar P. One end repelled, so P is a magnet.
Step 2, bar R. No effect at either end, so R is not magnetic.
Step 3, bars Q and S, first test. Both ends attract, and neither repels. Each is a magnetic material that was not magnetised at the start. The table cannot tell iron from steel.
Step 4, bars Q and S, second test. Q kept its magnetism after the strong magnet was removed, so Q behaves like steel, a permanent magnet once magnetised. S lost it at once, so S behaves like soft iron, a temporary magnet.
Notice that the first table settles P and R, and only the second observation separates Q from S.
The mistake to watch for
A common slip is to call every attracted bar a magnet.
Mistaken answer: “Bars P, Q and S are all magnets because they were attracted.”
Attraction occurs for unmagnetised iron too.
The correction is to ask “did anything repel?” before calling a bar a magnet. Attraction at both ends means magnetic material, not necessarily a magnet.
Check yourself
1. A bar is attracted at both ends by a south pole. What can you say about it?
Show answer
It is a magnetic material, possibly unmagnetised. It cannot be shown to be a magnet from this result alone.
2. A bar’s left end repels a north pole. What can you say about its left end?
Show answer
The left end is a north pole, because like poles repel, and so the bar is a magnet.
3. A student writes “the bar is magnetic” after seeing no effect at either end. Is this right?
Show answer
No. No effect means the bar is not a magnetic material. The conclusion contradicts the observation.
Where this leads next
Combine this with induced magnetism and permanent and temporary behaviour in the mixed practice set. The mistake log is useful for recording which reasoning step you miss.
Linking evidence to a conclusion is a habit worth building early. Our teachers work on it with you in online one-to-one Physics tuition.