Steel keeps its magnetism (permanent magnet), while soft iron loses it quickly (temporary magnet). An electromagnet is a coil of wire with a soft iron core. It is magnetic only while a current flows.
This comparison appears in magnetism and fields, often as a “which material should be used and why” question.
What makes a material magnetically hard or soft?
Both iron and steel are magnetic materials and both can be magnetised. The difference is how they behave afterwards.
Magnetically soft materials, such as soft iron, magnetise easily and demagnetise easily. Magnetically hard materials, such as steel, are harder to magnetise but keep their magnetism. You can think of it as how firmly the tiny magnetic regions stay lined up once the field is removed. The word “soft” refers to behaviour, not how the metal feels.
How do an electromagnet and a permanent magnet compare?
| Feature | Permanent magnet (steel) | Electromagnet (coil with soft iron core) |
|---|---|---|
| Magnetism stays when the current or field is removed? | Yes | No, only while the current flows |
| Can be switched off? | No | Yes |
| Strength can be changed? | No | Yes: more turns, larger current, or an iron core |
| Poles reversible? | No | Yes, by reversing the current |
| Typical uses | Fridge magnets, compass needles, loudspeaker magnets | Scrap-yard cranes, relays, electric bells |
An electromagnet is stronger with more turns, a larger current and a soft iron core. Reversing the current reverses the poles.
Worked example
A scrap-yard crane must pick up iron objects and then drop them in a new place. The designer is deciding between a coil with a steel core and a coil with a soft iron core. A test on two small models gave these results. (Invented data for practice.)
| Core | Paper clips held, current on | Paper clips held, current off |
|---|---|---|
| Soft iron | 12 | 0 |
| Steel | 9 | 4 |
Step 1, read the table. With the current on, the iron core holds more clips (12 against 9). With the current off, iron holds none and steel still holds 4.
Step 2, link to the job. The crane must release its load when the current is switched off. Steel would keep some magnetism, so the load might not drop.
Step 3, conclude with a reason. Use a soft iron core. It becomes strongly magnetic when current flows and loses its magnetism when the current stops.
Notice that the answer uses both columns of the table and ends with a reason tied to the job.
The mistake to watch for
A common slip is to say steel is better because it is “stronger”.
Mistaken answer: “Steel should be used because it keeps its magnetism.”
That is true, but it is the wrong property for a crane that must let go.
The correction is to start from what the job needs, then pick the material. A permanent magnet is right when the magnetism should stay, for example a compass needle. A temporary magnet is right when it must switch on and off.
A second slip is to call the coil alone the electromagnet. The soft iron core is what makes it strong.
Check yourself
1. Give one use for a permanent magnet and one for an electromagnet, each with the reason it suits the job.
Show answer
Permanent: a compass needle, because it must stay magnetised without any power. Electromagnet: a relay or scrap-yard crane, because the magnetism must be switched on and off. Any sensible pairs with reasons are acceptable.
2. Name two ways to make an electromagnet stronger.
Show answer
Increase the current, add more turns to the coil, or use a soft iron core. Any two.
3. A student hammers a steel bar that was a magnet, and it no longer picks up pins. Explain in one sentence.
Show answer
Hammering shakes the tiny magnetic regions out of alignment, so they point in random directions and their effects cancel.
Where this leads next
Next, interpret magnetic test results using the comparison above. You can also revisit induced magnetism to see why both materials are attracted before anything is magnetised.
If you can list the facts but lose marks on the “why”, that is a good reason to work with someone on your wording. Our teachers do this in online one-to-one Physics tuition.