Water wheel generator
Spoons or bottle caps on a wheel catch falling water and turn a motor to make electricity.
The big idea
Moving water carries energy. A wheel catches it and turns a generator. This is how hydropower works, at a size you can hold under a tap.
You will need
Tick things off as you gather them.
Step by step
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Step 1: Make the wheel
Glue the two discs onto the axle, a few centimetres apart, so they face each other like two wheels on a bicycle.
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Step 2: Add the paddles
Glue the spoons around the rim between the discs, spaced evenly, with the scoops facing the same way round. Let the glue dry.
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Step 3: Mount it
Build a frame so the wheel can turn freely. Connect one end of the axle to the motor shaft, using tape or a short piece of tube.
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Step 4: Wire the LED
Connect the motor terminals to the LED. If it does not light later, swap the LED legs.
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Step 5: Pour water on it
Place the wheel under a tap or pour from a bucket. Make the water land on the paddles, not on the axle.
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Step 6: Test and improve
Try a stronger flow. Try a higher drop. Try more paddles, or paddles at a different angle. Change one thing at a time.
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Step 7: Record it
Count the wheel turns per 10 seconds for each test. Note how bright the LED is.
What to look for
- More water, falling from higher, spins the wheel faster.
- Water that falls on the paddles works better than water that flows past.
- The wheel stops the moment the water stops. No water, no power.
Why it works
Water at a height has stored energy. As it falls, that energy turns into movement, and the paddles pass it to the wheel. The wheel turns the motor shaft, and the motor works as a generator. Big dams use exactly this idea, just with much more water and much bigger turbines.
Try this next
- Measure how the height of the water drop changes how fast the wheel spins.
- Collect the water in a bucket and reuse it, the way a pumped storage plant does.
- Compare your water wheel with your wind turbine.
Stay safe
Water and electricity do not mix. Keep the motor and wires dry. This low-voltage setup is safe, but never use mains power near water.
Link to the grid
Hydropower is one of the oldest ways to make electricity. Dams store water high up and release it when the grid needs power.
Learn how the grid worksMore wind, water and muscle experiments
Paper or plastic bottle wind turbine
Blades cut from a bottle spin a small DC motor that works as a generator and lights an LED.
Pedal-powered generator
An old bicycle turns a DC motor to light bulbs and shows how much effort electricity takes.
Bicycle dynamo lamp
A cheap bike dynamo lights an LED. A great way to see how a generator works.