The electromagnetic doorbell is an example of a self-interrupting electrical circuit. Pushing the bell button closes the switch (S) and connects the electromagnetic coil (M) to the battery (B). The activated electromagnet then attracts the clapper (A), which hits the bell but also interrupts the electric circuit at the contact (C). The magnet is then cut off and the clapper is released, closing the circuit…. This process is repeated as long as the button is depressed.