Electromagnetism
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Electric Bell.
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When the switch is pushed closed the circuit is completed
and current flows through the electromagnetic coil.
<br><br>
1. The iron striker is attracted to the electromagnet and strikes the bell.
<br><br>
Electric Bell

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<img src="Electric-Bell.gif" height="100" width="500"><br>

2. As the striker moves towards the bell, the contact is broken.<br><br>
Electricity stops flowing through the coil which loses its magnetism.
<br><br>
3. The spring returns the striker to its original position
which makes a new contact and so electricity flows again.<br><br>

Back to number 1 and the cycle repeats itself.<br><br>
The bell will continue to ring as long as the switch is held closed.