Science Projects on Rain Water Detectors

Written by sage kalmus
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Science Projects on Rain Water Detectors
Building a rain detector is an engaging way to learn about circuits. (circuit board components image by Michalis Palis from

Science projects with rain water detectors usually involve building simple detectors then brainstorming ways to adapt the detector so that it can activate simple electronic devices. These projects are most appropriate for students in grades 5 through 9, with most at-home detectors taking students about a week to complete building on their own. There are no safety issues associated with making rain water detectors.


Building a rain detector teaches students how electronic circuits work and how energy is transferred. Students learn about the components of communications systems, including a system's source, encoder and decoder, transmitter and receiver. It can also get them thinking about the relationship between water and energy conservation.


At the core of any rain water sensor is a basic electrical circuit. The electronics kit the student must purchase to complete this project contains all the necessary parts to build a functioning circuit. In putting the kit components together, a student learns how open and closed circuits behave. Converting the circuit into a rain detector is a simple matter of adding a sensor and a buzzer or other alarm.


In a simple rain detector, the sensor is nothing more than two strips of metal placed very close to one another without touching. The detector issues its alarm or turns on a light bulb when water touches the metal sensors and bridges the small gap between the strips. The rain water closes the electrical circuit and sends electricity to the indicator.

In-Class Activity

NASA developed a short in-class project building a rain water detector that teachers and children can perform within a single half-hour class period. This project can be performed using a battery, a wire, a switch, a light bulb, a socket, thumbtacks, aluminium foil, a spray bottle of water and a small block of wood. First the teacher or students build a basic circuit. Then they replace the switch in the circuit with a sensor and test it with a spritz from the water bottle.


Once your class has built a rain water detector, you can expand on the project by adapting the device to automatically turn off a sprinkler system in the presence of rain and turn it on again when the rain ceases. You can also adapt the detector to monitor the moisture level of a potted plant's soil and indicate when the plant needs watering.

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