# A student investigates the magnetic field produced by a solenoid connected to a direct current (d.c.) supply. Explain how the magnetic field inside and outside the solenoid is similar to, and different from, the magnetic field of a bar magnet.

> AQA A-Level Physics (7408) — 3.7.5 Magnetic Fields · Explain · 5 marks

## Mark scheme (5 marks)

1. The magnetic field outside the solenoid has the same shape as the field of a bar magnet (field lines emerge from one end and re-enter the other)
2. The solenoid has a north pole at one end and a south pole at the other, just like a bar magnet
3. The field inside the solenoid is strong and uniform, unlike the field of a bar magnet
4. The strength of the solenoid's magnetic field can be increased by increasing the current or increasing the number of turns of wire, unlike a permanent bar magnet
5. The direction of the magnetic field (and which end is north/south) can be reversed by reversing the direction of the current, which is not possible with a permanent bar magnet

## Key terms

- [solenoid](https://www.gradenine.co.uk/glossary/solenoid)
- [direct current](https://www.gradenine.co.uk/glossary/direct-current)

## Related

- [Revision notes for AQA A-Level Physics (7408)](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)

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Source: [GradeNine](https://www.gradenine.co.uk/q/a-student-investigates-the-magnetic-field-2d7c9b50) · Published by Druglandscape Ltd.