A cave surveyor uses a compass deep underground. After each reading, the compass case is rotated before the needle is allowed to settle again. There are no other magnets nearby. The north-seeking end returns to the same geographical direction each time.
Which property of the compass allows these readings to suggest that the Earth has a magnetic field?
The compass case is a permanent magnet that controls the needle
The needle has one end that is pulled directly towards geographical north
The needle is held in a fixed north–south position inside the case
The needle is a small bar magnet that is free to turn
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.