MAGNETISM AND MAGNETIC MATERIALS
2 marks · NormalState two differences between permanent magnets and electromagnets.
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
Permanent magnets have a constant magnetic field; strength is not easily changed. Electromagnets have a magnetic field only when a current flows; strength and direction can be easily changed.
Also accept: Permanent magnets are always magnetic, electromagnets are only magnetic when current flows.; Strength of permanent magnet field is fixed; for electromagnets, it's variable.
Show mark scheme and worked solution
Marking points
B1 · 1 mark · States that permanent magnets are always magnetic (or field is constant/fixed) while electromagnets are only magnetic when switched on (or current flows)
B1 · 1 mark · States that the strength (and direction) of an electromagnet can be changed easily, but not for a permanent magnet
Worked solution
Permanent magnets always have a magnetic field, and the strength is not easily changed. Electromagnets only work when electricity flows and their field can easily be made stronger or reversed.