I'M SINGING IN THE RAIN

Build your own rain alarm in this simple experiment

RN: 11020801 - ELECTRICITY & MAGNETISM > ELECTRICAL CURRENT

SUITABLE GRADES

7 & 8

DIFFICULTY

3

TIME REQUIRED

<1 week

SUPERVISION

ADVISED

INTRODUCTION [METHOD]

Many electrical devices are used as early warning systems such as burglar alarms, electric fencing systems and many more. Don't you think it will be useful to have an early warning system for rain to warn you to close the windows and bring in the clothes from the clothesline? In the following science experiment you will build a device that can detect rain as soon as the first drops start to fall:

STUFF YOU NEED [MATERIALS]

9-VOLT BATTERY
PLASTIC COATED COPPER WIRE
9-VOLT BUZZER / BELL
CLOTHESPIN
EFFERVESCENT TABLES
WIRE CUTTERS
RUBBER CEMENT

HOW TO PROCEED [PROCEDURE]

Electricity & magnetism science project - Electrical current

Cut two pieces of thin plastic coated wire of about 2m - 3m each (or long enough to reach from the outside of your window to the inside of your bedroom where the buzzer and battery will be positioned). Use wire cutters to strip clean the ends of both wires. Make sure that one end of each wire has at least 30mm clean stripped, and the other side of each wire about 100mm clean stripped.
Push the 100mm stripped clean ends of both wires through a small opening in your bedroom window, and connect the other ends to the terminals of a 9-V battery, and an electrical buzzer or a bell. Use another shorter piece of wire to connect the battery and the bell to each other as in the diagram above.
On the outside of your window, connect a wooden or plastic clothespin to the other ends of the wires by winding it several times over each of the front ends of the clothespin. This will be your two contact pieces to complete the electrical circuit.
Place a small effervescent-type of tablet in between the two prongs with the contact pieces of the clothespin to prevent them from touching. You may need to experiment with several types of tables to find the most suitable one, which degenerate the fastest when coming in contact with water or 'rain'.
Place the clothespin and tablet configuration on the sill of your window (you can use rubber cement to hold it in position).
When it starts to rain, the buzzer will go off and warn you that your clothes or curtains might get wet!

WHY IT WORKS [CONCLUSION]

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LEARN MORE FACTS

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GLOSSARY [TERMS]

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