Wouldn’t it be cool to have an alarm sound each time someone opened your door, lunch box, or secret drawer? It’s easy when you use a reed switch in your circuit! All you need to do it substitute this sensor for the trip wire and you’ll have a magnetic burglar alarm.
The first thing you need to do is get your reed switch out, because we have to tear into it in order to get the part we need. Here’s what you need:
Materials:
- reed switch
- magnet
- LED
- AA case
- 2 alligator wires
- 2 AA batteries
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Download Student Worksheet & Exercises
Exercises
- Where does the magnet need to be located in order for your circuit to work?
- How does the switch work? Draw a picture and label the parts that make it work in the circuit.
- Can the switch be activated through the side of a drawer, so that the switch is in the inside and the magnet is on the outside?
- Which way does the magnet activate the switch the best? How are the poles oriented relative to the switch?
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