A student wants to demagnetise a strongly magnetised steel bar. The bar is oriented in an East-West direction to avoid any influence from the Earth's magnetic field.
Which of the following methods will successfully demagnetise the steel bar?
Placing the bar inside a solenoid carrying a steady direct current (d.c.) and keeping it there.
Stroking the bar repeatedly from one end to the other with one pole of a permanent magnet.
Placing the bar inside a solenoid carrying an alternating current (a.c.) and slowly withdrawing it.
Placing the bar inside a solenoid carrying a steady direct current (d.c.) and slowly withdrawing it.
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.