A robotic arm uses a permanent magnet to move identical steel discs. A field-line map is used to choose where a disc should be positioned.
The table shows the average separation between neighbouring field lines at four positions on the same map.
| Position | Average separation between neighbouring field lines in mm |
|---|---|
| R | 2 |
| S | 7 |
| T | 4 |
| U | 11 |
Give the order of the positions from the greatest force on a steel disc to the smallest force on a steel disc. Explain your answer.
80 exam-style questions on AQA GCSE Physics 7.1 Permanent and induced magnetism, magnetic forces and fields, covering 7.1.1 Poles of a magnet and 7.1.2 Magnetic fields. Each one has a worked solution and a mark scheme showing where the marks go.