Question

Write 2 properties of material which is suitable for making permanent magnets

Answer 1

1) By coiling a copper wire around a soft iron
2) rub A permanent magnet to a soft iron bar

Answer 2

Permanent magnetic materials should have high retentivity so that the magnet is strong and high coercivity so as to withstand against stray magnetic fields,temperature fluctuations or minor mechanical damage.Steel is one favoured choice.

Core of electromagnets are made of ferromagnetic materials which have high permeability and low retentivity.Soft iron is an example.Electromagnets are used in electric bells,loud speakers and tekephone diaphragms.Giant electromagnets are used in cranes to lift machinery and bulk quantities of iron and steel.