The wire is sanded in three-quarters so that only 1/4 is left with enamel. This can be seen in another way. 3/4 of the wire will be conductive, while 1/4 (the one that has the enamel) will be isolated. This leads to apply a voltage difference in the contact of any metal with the 3/4 parts of the wire unglazed behave as a driver while 1/4 (the enamel) will not be driver. Now when you have wound the wire we have emulated a coil, which physically possess the quality of accumulating power in the form of a magnetic field.
When you apply a potential difference between both ends of the coil, for she circulates current through which is accumulated by a magnetic field in the winding of the wire or in the area where we have rolled the same. Kelvin really knows how to handle gear motors.
How to create a gear motor
This magnetic field has a polarity, which in a moment is the same as the polarity that has the magnet so that poles of the same will repel each other and thus the coil moves. When you move the ends of the wire are positioned on the terminals of the battery by its area glazed which works as an insulator to the passage of current. In this case the coil is unloaded by which changing the polarity, which is reflected in that at one time has the opposite polarity to the magnet and therefore is attracted to, which generates a movement.
The continuous movement causes the terminals to touch the wire in the zone of conduction (3/4 parts without glaze), and zone isolation (1/4 Polish) makes the coil charge and discharge, which in turn generates changes in its polarity and all of this by being in continuous interaction with the magneto generates that attracts and repels getting as a result the movement of the motor.
The body of the rotor is a cylinder of tin-plate of 5 cm height and 5 cm in diameter. The shaft that is soldered to the body is a straight wire of 2 mm diameter and 11 cm in length, with its lower end tapered (give very good result the rays of a bike). The construction of the rotor must done carefully so that your dough is well-balanced. It is not necessary that the rotor have the form of a jar. It can also be built in the shape of squirrel-cage using three cuts of tin of approximately 8mm in width (this arrangement is shown in the photo above)
With a strip of aluminium sheet 1mm thick and 2 cm wide is fabricated an arch that will hold the rotor in a vertical position. In the center of its upper end carries a drilling 3mmm diameter.