Five sensors and five applications are shown below. Draw a line to link each sensor to its most appropriate application. Sensor Application Light sensor Monitor the pollution levels in a river Moisture sensor Control the switching off and on of street lights Gas sensor Detect intruders breaking into a building pH sensor Monitor the amount of water left in clothes in a dryer Pressure sensor Monitor acidity levels in the soil in a greenhouse

1. (a)Five sensors and five applications are shown below. Draw a line to link each sensor to its most appropriate application. Sensor Application Light sensor Monitor the pollution levels in a river Moisture sensor Control the switching off and on of street lights Gas sensor Detect intruders breaking into a building pH sensor Monitor the amount of water left in clothes in a dryer Pressure sensor Monitor acidity levels in the soil in a greenhouse[4]
2. (b)Automatic doors in a building are controlled by the use of infrared sensors and a microprocessor. Describe how the sensors and the microprocessor are used to automatically open a door as a person approaches.[4]

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