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When the bell switch is pressed, this completes the circuit. So, the electromagnet becomes magnetised and is attracted to an iron armature, which then hits the bell. Because the armature has moved it has broken the circuit so it moves back. When it moves back it completes the circuit again and so carries on ringing the bell like this until the switch is released When the bell switch is pressed, this completes the circuit. So, the electromagnet becomes magnetised and is attracted to an iron armature, which then hits the bell. Because the armature has moved it has broken the circuit so it moves back. When it moves back it completes the circuit again and so carries on ringing the bell like this until the switch is released.

A loudspeaker is an electro acoustic transducer that converts an electrical signal into sound. The speaker moves in accordance with the variations of an electrical signal and causes sound waves to propagate through a medium such as air or water. Loudspeakers are the most variable elements in a modern audio system and are usually responsible for most distortion and audible differences when comparing sound systems.

All industrial lifting magnets are electromagnets. From the outside, you see only a heavy cast or machined steel casing and a cover plate. Inside is a carefully fabricated winding of aluminium or copper electrical conductor. Each layer of the winding is separated by a thin layer of insulation. The cover plate is a sheet of manganese, providing an extremely hard, non-magnetic protective shield for the coils.

An electric door lock assembly including a solenoid having a plunger movable between retracted and extended positions, and a mounting bracket for mounting the solenoid to a door or door frame so that the plunger operatively moves along a vertical axis between the retracted and extended positions. A locking arm or bolt is pivotally connected at a proximal end thereof to the plunger.

A relay is an electrically operated switch. Many relays use an electromagnet to operate a switching mechanism, but other operating principles are also used. Relays find applications where it is necessary to control a circuit by a low-power signal, or where several circuits must be controlled by one signal. The first relays were used in long distance telegraph circuits, repeating the signal coming in from one circuit and re- transmitting it to another. Relays found extensive use in telephone exchanges and early computers to perform logical operations. A type of relay that can handle the high power required to directly drive an electric motor is called a contactor. Solid-state relays control power circuits with no moving parts, instead using a semiconductor device triggered by light to perform switching.

By Jack Lewis and JP