Year+13+AC

__**Alternating Current Electricity**__

Alternating current (AC) electricity is the type of electricity commonly used in homes and businesses throughout the world. AC can employ capacitors and inductors in electronic circuitry, allowing for a wide range of applications.While direct current (DC) electricity flows in one direction through a wire, AC electricity alternates its direction in a back-and-forth motion. The direction alternates between 50 and 60 times per second (50 Hz or 60 Hz), depending on the electrical system of the country. AC electricity is created by an AC electric generator, which determines the frequency. A low frequency eases the design of low-speed electric motors, particularly for hoisting, crushing and rolling applications, and commutator-type traction motors for applications such as railways, but also causes a noticeable flicker in incandescent lighting and an objectionable flicker in fluorescent lamps.

Many electrical devices—like light bulbs—only require that the electrons move. They don't care if the electrons flow through the wire or simply move back-and-forth. Thus a light bulb can be used with either AC or DC electricity. The regular back-and-forth motion of the electrons in a wire when powered by AC electricity is periodic motion, similar to that of a pendulum.Because of this periodic motion of the electrons, the voltage and current follow a sine waveform, alternating between positive (+) and negative (−)

The ability to readily transform voltages is the main reason we use AC instead of DC in our homes. Since high voltages are more effecient for sending electricity great distances, AC electricity has an advantage over DC. This is because the high voltages from the power station can be easily reduced to a safer voltage for use in the house. Changing voltages is done by the use of a **transformer**. This device uses properties of AC electromagnets to change the voltages.

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resonant circuits: http://www.walter-fendt.de/ph14e/osccirc.htm