Clamp & stand x 2
Using the compass mark a circle of 12cm diameter on the card and another of 3cm diameter in the middle, then cut out the large circle.
Mark points around the edge of the circle at the 12, 3, 6 and 9 o'clock positions, mark again at the midpoint between these, and again at the midpoint between the last set of points. You will have 16 points marked around the edge. Use a ruler to mark a line joining opposite points.
Attach the centre of the circle to the motor/generator spindle firmly using glue.
Cut from the edge to the inner circle at the 12 and 6 o'clock positions to make a turbine with 2 blades - you may need to gently curve the card.
Attach the wind turbine to the clamp stand, with the hairdryer in the other so that there is 10cm between the hairdryer nozzle and the turbine blades.
Connect the turbine to the voltmeter.
Turn on the hairdryer and record the reading shown on the voltmeter.
Adjust the turbine blades, cutting it so that it now has 4 evenly spaced elements. Repeat the measurement of the output, ensuring that the distance o the hairdryer remains at 10cm.
Repeat twice more, with 8 blades and 16 blades on the turbine.
The hairdryer may get hot after prolonged use. The turbine blades could get caught up in long hair, so it should be tied back.