# A solenoid is used to lift steel bolts in a factory. Describe how the solenoid produces a magnetic field and explain two ways the engineer could increase the strength of this magnetic field to lift heavier bolts.

> OCR A-Level Physics B: Advancing Physics (H557) — 4.2 Energy, power and resistance · Describe and Explain · 5 marks

> A factory uses a solenoid connected to a direct current power supply to sort and lift small steel bolts on a production line. The engineer notices that the solenoid sometimes fails to lift heavier bolts and wants to make the magnetic field stronger.

## Mark scheme (5 marks)

1. Current flowing through the coiled wire produces a magnetic field (around the wire / inside the solenoid)
2. The coiling of the wire causes the individual fields to align / combine to produce a single stronger, uniform magnetic field
3. First improvement: increase the current (flowing through the solenoid) — this increases the magnetic field strength
4. Second improvement: increase the number of turns (coils / loops) of wire — more turns increases the magnetic field strength
5. Adding an iron core (inside the solenoid) increases the magnetic field strength because it is easier for magnetic field lines to pass through iron than air

## Key terms

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

## Related

- [Revision notes for OCR A-Level Physics B: Advancing Physics (H557)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe and 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-solenoid-is-used-to-lift-70fc1e6a) · Published by Druglandscape Ltd.