A student investigates how the magnetic field around a wire changes with distance from the wire.
The current is kept the same. The student records how far a plotting compass needle turns at different distances.
Table
| Distance from wire (cm) | Angle the needle turns (∘^\circ∘) |
|---|---|
| 1.0 | 60 |
| 2.0 | 40 |
| 3.0 | 28 |
| 4.0 | 20 |
Which conclusion is correct?
The field gets weaker further from the wire, by less for each extra cm
The field gets weaker further from the wire, by the same amount each cm
The field gets stronger further from the wire, by less for each extra cm
The field does not depend on distance, because the current is the same
44 exam-style questions on OCR GCSE Physics 4.1 Magnets and magnetic fields, covering 4.1.1 Magnetic poles, attraction and repulsion, 4.1.2 Permanent and induced magnets, 4.1.3 The magnetic field of a magnet, 4.1.4 Compasses and the Earth's magnetic field, 4.1.5 The magnetic field around a current-carrying wire, 4.1.6 Field strength, current and distance, and 4.1.7 Solenoids and electromagnets. Each one has a worked solution and a mark scheme showing where the marks go.