Which observation of dipping compasses is the best evidence that the core of the Earth is magnetic?
The needle points north in every country, wherever the compass is used
The needle dips more steeply in places where there are iron ore deposits
The dip changes smoothly with position, like the field of a bar magnet
The needle stays horizontal unless a magnet is brought near the compass
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.