A student wishes to demagnetise a permanently magnetised steel bar.
Which of the following procedures will successfully demagnetise the bar?
Heating the bar strongly and letting it cool while aligned in an east-west direction.
Connecting the ends of the bar to a high-voltage d.c. power supply.
Stroking the bar repeatedly in one direction with the north pole of a bar magnet.
Cooling the bar to extremely low temperatures in liquid nitrogen.
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.