A simple electric bell is shown
in the diagram - it works like this. When the switch S is closed current flows round the circuit,
through the electromagnet - along the spring - through the contacts - through the adjusting
screw and back to the battery again.
The electromagnet therefore attracts the soft
iron armature and the striker hits the gong once.
As soon as the armature is
attracted the contacts are opened and so the current stops flowing.
This switches
off the electromagnet, the spring pulls the armature away — the contacts meet again and so
the current starts flowing again. This is repeated over and over again and so the bell
rings.
