Current Electricity and Magnetism — Science STD 8 — Question

The working of an electric bell is based on the magnetic effect of current.
When the key is pressed, the circuit gets completed and current passes through it causing the electromagnet to get magnetised which in turn attracts the armature.
This movement of the armature causes the hammer to strike the gong. 
However when the armature moves towards the gong the connection between the spring strip and adjusting screw is lost which breaks the circuit and the current flow is stopped thus demagnetising the electromagnet.
This causes the armature to return to its original position and it is thus pulled back due to the spring effect of the spring strip.
This process is called a make and break circuit.