Per16_over

# Per16_over - Preview of Period 16 Motors and Generators...

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Preview of Period 16: Motors and Generators 16.1 DC Electric Motors What causes the rotor of a motor to spin? 16.2 Simple DC Motors What causes a changing magnetic field in the simple coil motor? 16.3 St. Louis DC Motor What causes a changing magnetic field in the St. Louis motor? 16.4 AC Electric Motors Do alternating current motors need commutators? 16.5 Building a Buzzer What causes a changing magnetic field in the buzzer? 16-1

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Act 16.1: Electric Motors Motors convert electrical energy into kinetic energy using the forces between magnetic fields to spin a rotor. Current in the wires makes the rotor an electromagnet (a solenoid). The ends of the rotor (the poles of its electromagnet) are attracted to and repelled by the poles of nearby magnet(s). To keep the rotor spinning, its poles must reverse their polarity. This requires a changing current in the coil of the rotor. Rotor Rotor Coils The rotor consists of a metal rod wrapped in a coil of wire and mounted on a pivot, which allows the rotor to spin. 16-2
Act 16.1: Spinning a Permanent Magnet with Another Permanent Magnet N S N S Magnet on a pivot Magnet in your hand The magnet spins until its south end is aligned with the north end of the magnet in your hand. If you remove the magnet in your hand just as the south pole of the spinning magnet approaches it, the spinning magnet’s motion causes it to continue to spin. If you flip and replace the magnet in your hand at the appropriate time, the spinning magnet again rotates to align its south pole with the north pole of that magnet. Replace the permanent magnet in your hand with an electromagnet (a solenoid). Why must you turn the current on and off to make the magnet spin? 16-3

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Act 16.1: Spinning an Electromagnet N S S N Rotor Coils Rotor Spinning Electromagnet Permanent Magnet The electromagnet spins until its south pole is aligned with the north pole of the magnet. If the current in the electromagnet is turned off
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## This note was uploaded on 06/11/2011 for the course PHYSICS 103 taught by Professor Staff during the Spring '10 term at Ohio State.

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Per16_over - Preview of Period 16 Motors and Generators...

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