Electric Motor Physics Essay

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ELECTRIC MOTOR ELECTRIC MOTOR Electric motors are everywhere! In your house, almost every mechanical movement that you see around you is caused by an AC (alternating current) or DC (direct current) electric motor. A simple motor has six parts: * Armature or rotor * Commutator * Brushes * Axle * Field magnet * DC power supply of some sort The Motor Effect When a current is passed along a wire in a magnetic field, a force may be exerted on the wire. This is the motor effect. The force depends on the angle between the wire and the magnetic field lines. The force is biggest when the wire is perpendicular to the field lines, nil when parallel. An electric motor is designed to use the motor effect. We can change its speed by alternating the current, and reverse its speed by reversing the current. The coil in the motor shown (the armature coil) is forced to rotate. The coil is connected to a battery via two metal or graphite brushes. These brushes are fixed onto a split-ring commutator which is connected to the rectangular coil. When a current is passed through the coil, it spins because: * a force acts on either side due to the motor effect * the force on one side is in the opposite direction to the other side The split ring commutator reverses the current every half-turn of the coil – and because the sides swap over every half turn, the coil is pushed continually in the same direction over and
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