Answer to Question #102256 in Electricity and Magnetism for Richard Foo

Question

I'm thinking of making a contraption that can produce electricity by the 'wind' cars produce while the car is moving. My idea is that i build some cylidrincal contraption that can be fitted onto the light poles on highways so that the wind of the cars can rotate the cylinder. The cylinder consists of two layers. The inner layer is fitted onto the light pole with magnets and the outer layer consists of the copper coil that rotates to cut the magnetic flux to produce an induced current. My question is is there any way to let the outtrt layer rotate freely and how to connect the wires so that it wont get entagled when the outer layer is rotating. Thanks!

Answer 1

Thank you! Quite interesting idea, but to figure out how much energy in can generate, we need to conduct many experiments and test different turbines. There is a way that would allow you to connect the outer rotating layer to the main circuit. That device is called collector and it is being widely used with brushes in DC motors, subway trains, trolleybuses, and trams. Here is a schematic picture applied to your situation:

The outer piece rotates but the brushes conduct electricity to the main circuit. The magnets are firmly fixed inside the case. However, we can put the cylindrical insulating case with coils in two large ball bearings.