Which of the following would be the most effective method to demagnetise a permanently magnetised steel bar?
Place the bar inside a solenoid connected to a large direct current (d.c.) and then switch the current off.
Place the bar inside a solenoid connected to an alternating current (a.c.) and slowly withdraw the bar.
Stroke the bar repeatedly with the north pole of a strong permanent magnet in a single direction.
Align the bar in a north-south direction and hit it gently with a soft rubber mallet.
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.