Question

Why is pure iron not used for making permanent magnets? Name one material used for making permanent magnets. Describe how permanent magnets are made electrically. State two examples of electrical instruments made by using permanent magnets.

Answer 1

• Pure iron cannot retain its magnetism for long time. Hence it cannot be used for making permanent magnet. 
• Cobalt-steel or some alloys of iron such as ALNICO are used for making permanent magnet. 
• Formation of permanent magnet electrically A current carrying solenoid is used to magnetise steel rod. Steel rod is kept inside the solenoid. A strong uniform magnetic field produced by the current carrying solenoid magnetise it. The magnet so formed retains the magnetism even after switching off the current in solenoid. 
• Permanent magnets are used in (i) Galvanometer and (ii) loudspeaker