Question

The material used for making the armature of electric bell is

• A. aluminum
• B. soft iron
  
• C. steel
• D. bronze

Answer 1

The correct option is B soft iron

An electric bell contains an electromagnet, consisting of coils of insulated wire wound round iron rods.
When the push switch is depressed, the circuit is closed. Current passes through the electromagnet winding and the core becomes magnetized. The magnetized core attracts the iron armature which makes the striker hits the gong. However, the movement of the armature opens the make and break switch which switches the electromagnet off. The iron armature springs back to its original position, closing the make and break switch and start the cycle again. Soft iron is used to make electromagnets as it gains and losses magnetism quickly depending on existence of magnetic fields.
The armature is also made of soft iron which can induce magnetism rapidly. No matter what direction is the current flow, the bell rings continuously as long as the push switch is closed because any pole induces the armature.