# A student sets up an electromagnet by wrapping a wire into a solenoid and connecting it to a power supply. The student then places a soft iron core inside the solenoid. Explain how the solenoid produces a magnetic field and why inserting the soft iron core increases the strength of that field.

> Edexcel A-Level Physics (9PH0) — 12.1 Newtonian gravity · Explain · 5 marks

> An electromagnet consists of a solenoid with a soft iron core. The student notices that the electromagnet can lift more paperclips when the iron core is inserted than when the solenoid has no core.

## Mark scheme (5 marks)

1. Current flowing through the wire produces a magnetic field around each turn of the coil
2. Coiling the wire causes the individual magnetic fields from each turn to combine / align to produce a single, stronger, (almost) uniform magnetic field along the centre of the solenoid
3. The overall field shape of a solenoid is similar to that of a bar magnet (with a north and south pole)
4. The soft iron core becomes an induced magnet when placed inside the solenoid (magnetism is induced by the solenoid's field)
5. It is easier for magnetic field lines to pass through iron than through air, so the iron core increases the overall magnetic field strength of the electromagnet

## Key terms

- [solenoid](https://www.gradenine.co.uk/glossary/solenoid)
- [electromagnet](https://www.gradenine.co.uk/glossary/electromagnet)
- [magnetic field](https://www.gradenine.co.uk/glossary/magnetic-field)

## Related

- [Revision notes for Edexcel A-Level Physics (9PH0)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/a-student-sets-up-an-electromagnet-0091d824) · Published by Druglandscape Ltd.