To demonstrate that the basic structure of a motor and electric generator is the same. The construction of the apparatus is such that all the parts are readily observable. When the apparatus is turned by turning the wheel by hand and a mounted LED( provided ) is inserted in the 4 mm sockets the LED lights up thereby demonstrating the working of a generator. Then instead of the LED if current is provided by a battery in the same 4 mm sockets the apparatus acts as a motor. Supplied without battery.