Magnetism
4 marks · NormalTwo bar magnets are used in an experiment. One is made from iron and the other from steel.
Explain why steel is used for making permanent magnets, but iron is not.
When a small iron paperclip is placed next to a steel magnet, describe what happens to the paperclip and explain why.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) Steel is magnetically hard and keeps its magnetism, making it suitable for a permanent magnet. Iron is magnetically soft and loses magnetism rapidly, so it is not suitable for a permanent magnet. · must show Steel is hard; keeps magnetism, Iron is soft; loses magnetism
(b) The paperclip is attracted to the steel magnet and becomes a temporary magnet (induced magnetism). The induced magnetism disappears when the steel magnet is removed. · must show Paperclip attracted and becomes magnetised, Induced magnetism is temporary
Common mistakes: Reversing which is soft and which is hard; Omitting that induced magnetism is temporary
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Correctly identifies steel as hard and suitable for permanent magnets.
B2 (a) · 1 mark · Correctly identifies iron as soft and unsuitable for permanent magnets.
B1 (b) · 1 mark · States paperclip is attracted and becomes temporarily magnetised.
B2 (b) · 1 mark · Mentions induced magnetism disappears after removing magnet.
Worked solution
(a) Steel is magnetically hard, so it stays magnetised when made into a magnet. Iron is magnetically soft, so it loses its magnetism easily and is not suitable for permanent magnets.
(b) The iron paperclip is attracted to the steel magnet and becomes an induced magnet, but it loses its magnetism quickly once the steel magnet is removed.