Wind turbines

I've been spending some time cutting slots into corks, fitting rectangular pieces of card into the slots, and gluing small plastic pulleys on the ends of the corks. 

Why?  You may well ask.

These are for a Physics practical which will test how the number of blades on a wind turbine can affect the output of the turbine. The pulleys will be fitted on to the spindles of small electric motors;  air will then be blown at the "turbine blades" (from a hair dryer) to make the motor spin;  the motor will act as a dynamo and generate a voltage.  Students will be able to add or remove blades to see the effect on the output voltage with a constant airflow.

Well, it kept me amused today.