Final answer:
A soil moisture sensor measures water content in soil and has applications in agriculture and environmental monitoring. An IR sensor uses infrared signals to detect objects and measure distances, with uses in remote controls, alarms, and robotics.
Step-by-step explanation:
Soil Moisture Sensor
A soil moisture sensor measures the water content in soil. Commonly, it consists of two probes that act as a variable resistor whose resistance varies depending on the soil's moisture content. When the soil is wetter, the electrical conductivity increases, leading to less resistance, and when dryer, the conductivity decreases, resulting in higher resistance. This change in resistance can be measured using a simple circuit and can be calibrated to give the actual moisture content.
Applications of soil moisture sensors include agriculture for irrigation control, landscaping, and environmental monitoring. They help conserve water by providing data to optimize irrigation schedules according to soil moisture levels.
IR Sensor
An IR sensor operates by emitting an infrared signal and then detecting the reflected signal to measure distance or detect objects. It consists of an IR LED and a photodiode. When the emitted IR radiation hits an object, it is reflected back and detected by the photodiode. The intensity of the received IR radiation indicates the distance of the object or its presence.
Applications include remote controls, intruder alarms, object counters, and line-following robots in robotics.