What happens if the material used to make the armature of an electric bell is charged to steel ?

Options

A. There will not be any change in the ringing of the bell.
B. Loudness of the bell ring gradually reduces.
C. Loudness of the bell ring gradually increases.
D. The hammer hits the gong for once and is likely to stop.

Answer

D

Explanation

The armature of an electric bell is generally made of soft iron because in an electric bell the armature needs to hit the gong several times as long as the push type switch is in ON condition. This can be achieved if the armature is made of material which has less magnetic retentive property (i.e. the material behaves like magnet only when the current passes through the insulated wire which is wound around it). Due to this temporary magnetism, the hammer hits the gong several times and this is how the bell rings in case of an electric bell. If the armature is made of steel, it exhibits permanent magnetism. Therefore, the hammer hits the gong once and remains in the same position.
Hence, the correct option is (d).