The fixed component of our motor is a pair of nails, which become magnetized when electrical current from a battery passes through them. These are wired permanently to the battery, so their north and south poles are fixed and do not change. They send power through the brushes (bared end wires standing up) into the rotor. The rotor, which is allowed to rotate freely on the stand provided for it, takes the electrical current in through the wires sticking out from it, and sends it around and around the paperclip, making IT a magnet too! When the motor first receives electrical power, the rotor becomes magnetized this way: This immediately causes the rotor to be repelled from the permanent post magnets on either side: (...since 'like' poles repel.) But look what happens when the rotor rotates to the opposite side ... The electrical current is now flowing through the rotor backwards. This causes the north and south poles to switch ends! But this means that the poles are again repelling ... Every time the rotor is repelled away, its polarity changes, and it is repelled away again. This causes the rotor to continuously rotate! The brushes, rotor, and stands must be aligned very carefully in order to make the motor turn efficiently. Curving the brushes also helps them make contact longer during each revolution.   An alternate motor design, made by Josh Wasylciw. The brushes in this motor touch alternate sides of the rotor axle, which has had one side painted.

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Physics | Worsley School