A student wishes to demagnetise a strongly magnetised iron bar. Which of the following procedures would successfully demagnetise the bar?
Placing the bar inside a freezer for several days.
Connecting the bar to a direct current (d.c.) power supply.
Heating the bar strongly and then hammering it repeatedly while it is aligned in an east-west direction.
Stroking the bar in one direction with a woollen cloth.
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.