Which of the following methods can be used to demagnetise a permanent steel bar magnet?
Cool the magnet to a very low temperature.
Place the magnet inside a solenoid connected to an alternating current (a.c.\text{a.c.}a.c.) supply and slowly withdraw it.
Place the magnet inside a solenoid connected to a direct current (d.c.\text{d.c.}d.c.) supply.
Stroke the magnet repeatedly from one end to the other with a piece of unmagnetised soft iron.
169 exam-style questions on CIE IGCSE Physics Simple phenomena of magnetism, covering Simple phenomena of magnetism. Each one has a worked solution and a mark scheme showing where the marks go.