electric bell

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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.

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