Electric bell

Many objects around you contain electromagnets. They are found in electric motors and loudspeakers. Electric bells like the ones used in most schools also contain an electromagnet. The slideshow describes how an electric bell works:

Electric bell, showing a battery, open switch, metal arm, gong and electromagnet. As the switch is open, the metal arm is away from the gong.

The switch is open and the metal arm is away from the gong.

The cycle shown in the slideshow repeats as long as the switch is closed.

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