# Describe how iron filings and a plotting compass can each be used to show the direction of a magnetic field around a bar magnet, and state one advantage of using a plotting compass rather than iron filings for this purpose.

> Cambridge International IGCSE Physics (0625) — 4.1 Simple phenomena of magnetism · Describe · 4 marks

## Mark scheme (4 marks)

1. Iron filings method: paper is placed on top of (or over) the bar magnet and iron filings are sprinkled onto the paper; tapping the paper causes the filings to align along the magnetic field lines
2. Plotting compass method: the compass is placed next to the magnet and the needle points in the direction of the magnetic field at that point; dots are marked and the compass is moved progressively to trace a field line
3. Field lines point / arrows go from north pole to south pole (direction is shown)
4. Advantage of plotting compass: it shows the direction of the field (whereas iron filings only show the shape/pattern of the field lines but not the direction)

## Key terms

- [magnetic field](https://www.gradenine.co.uk/glossary/magnetic-field)
- [plotting compass](https://www.gradenine.co.uk/glossary/plotting-compass)
- [bar magnet](https://www.gradenine.co.uk/glossary/bar-magnet)

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