electric bell

An electric bell. The bell consists of two solenoids (wire coils) around soft iron cores that are connected by a soft iron yoke. The solenoids are made from a continuous piece of wire, one end of which is connected to a battery, and the other to the armature with hammer attached. Contacts are spring mounted to the armature. A wire connects the contact to the switch. When the switch is flipped, a current flows through the circuit and the cores become magnetized. This attracts the armature causing the hammer to strike the bell and the contacts to be broken, breaking the circuit.

Bell that makes use of electromagnetism. A direct current (from a battery) flows through a wire-wound coil on an iron core (an electromagnet). The electromagnet attracts an iron armature, and a clapper or hammer fixed to the armature strikes the bell. The armature acts as a switch, whose movement causes contact with an adjustable contact point to be broken, so breaking the circuit and switching off the electromagnet. A spring rapidly returns the armature to the contact point, once again closing the circuit, and the process is repeated. The armature oscillates back and forth, causing the clapper or hammer to strike the bell repeatedly.