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GCSE Design and Technology · key term
An electrically operated switch whose energised coil creates a magnetic field that moves an armature and changes the contacts in another circuit.
Used by Edexcel and Eduqas
Specification 5.2.2 · Paper 1
Revise: Control Devices and ComponentsThis is useful because many electronic control chips cannot supply enough current directly for a motor or relay coil. The chip supplies the control signal, while the transistor switches the load current supplied by the power source.
Component 1
An electrically operated switch in which current through a coil creates a magnetic field that moves switch contacts.
Distinguish a relay’s coil circuit from the circuit being switched. A transistor may still be needed to drive the coil.
Normally open and normally closed relay contacts describe their state when the coil is not energised.
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A relay is an electrically operated switch. Current through its coil produces a magnetic field, which attracts a movable metal armature and changes the position of the switch contacts. When the coil is no longer energised, the contacts return to their resting position.
