Ah! That explains it — what your son found is a bicycle dynamo. 🚲⚡
Here’s a clear breakdown:
🔹 What a Bicycle Dynamo Is
- A small device attached to a bike wheel
- Converts mechanical energy (from the spinning wheel) into electrical energy
- Powers lights (front and rear) without batteries
🔹 How It Works
- The dynamo has a roller or small gear that rubs against the bike tire or hub
- When the wheel spins, it turns a magnet inside coils of wire
- This generates electric current to power lights
🔹 Key Facts
- Often called a bottle dynamo (because of its shape) or hub dynamo (if integrated in the wheel hub)
- Can generate around 3 watts at 6 volts — enough for standard bike lights
- Works only when the bike is moving
⚡ Fun Tip
If it’s lying in the garden, you can test it by spinning the roller with your hand near a small light bulb — you’ll see it produce electricity!
If you want, I can explain the different types of bicycle dynamos and which one is best for modern bikes — it’s actually pretty interesting for DIY bike lighting.
Do you want me to do that?
