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GCSE Design and Technology · key term
An input component used to detect wetness or moisture content through a change in an electrical property.
Used by Edexcel and Eduqas
Specification 5.2.1 · Paper 1
Revise: SensorsFor example, an automatic watering system needs to detect whether soil is dry. Its moisture sensor provides the input; the control circuit decides when watering is needed; a pump provides the output. The sensor does not itself make every decision or supply the power needed by the pump.
Component 1
An input device that detects moisture. A simple conductive probe uses two exposed contacts: moisture allows current to pass between them, reducing the resistance across the probe.
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A simple moisture sensor, or moisture probe, uses two exposed conductive contacts, such as copper contacts, separated by a gap. When dry, very little current passes between them. Moisture bridging the contacts allows current to flow, so the resistance across the probe falls as it gets wetter.
