ESE 121 Lecture Notes - Lecture 16: Sine Wave, Short Circuit, Farad
4 Apr 2017
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Document Summary
When we use dc, the flow of current is in only one direction. With ac, the direction changes from positive to negative in a sinusoidal fashion. Power generation that we use in our homes is produced by rotating generators which naturally produce ac by turning magnets around a wire coil. Ac is far more efficient to run over long lengths. As the magnets rotate around the wire coil, the polarity of the voltage changes from positive to negative. The ac system that we use in the united states runs at 60hz. Meaning that the polarity switches direction 60 times per second. So ac won out over dc and that"s how electrical power is transmitted in the us. Transformers are relatively simple devices and solved the transmission problem that edison was struggling with. Transformers can take high-voltage, low-current and turn it into low-voltage, high-current. The way that it works is by magnetic induction.
