Build a Disk Siren

Introduction

If you live in an urban area, you probably hear them almost every day: sirens. Police cars, ambulances, fire trucks—they all can come blaring. Their wailing sounds are piercingly loud to help alert others to clear the road in front of them. But have you ever thought about how this loud noise is generated? Make your own disk siren in this activity and find out for yourself.

Credits

Materials

• Plastic lid, the type you see on large yogurt tubs, preferably 16 cm diameter.
• Scissors
• Protractor
• Ruler
• Permanent marker
• Double-sided foam tape, a small piece is enough.
• Hole punch
• Cordless electric high-power screwdriver that reaches at least 1,000 rotations per minute. You should only use it with adult supervision.
• Small bit for the screwdriver
• Straw
• Paper clip or needle
• Adult helper