Alternating Current and Direct Current Illustrated with Labels

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Alternating current (AC) is the type of electricity wherein the electric charges traveling on a circuit goes in reversing directions periodically. This means that if there are 2 terminations A and B, at a certain time the charges flow from point A to point B and afterwards the charges flow from point B to point A. The most common waveform of an AC is a sine wave. Below is the diagram of a simple AC generator (image courtesy of http://www.ac-motors.us):

There are 4 main parts of a simple AC generator: the magnet, the coil made of electric conducting material, the slip rings and the carbon brushes. The magnet will produce magnetic forces between the north and south poles. If a coil is placed in between these magnetic poles and rotated, the magnetic forces will be disturbed and this event will produce electric current on the coil. The slip rings that are touching the brushes will then allow the flow of charges to the conductors where the load is connected. The flow of charges goes in proportion to the motion of the coil. The position of the coil determines the direction of the flow of charges in the coil. One complete rotation of the coil produces one complete cycle of AC.

Below is a sample diagram of an AC voltage with a sine wave waveform (image courtesy of http://www.electronicsarea.com):

There are 4 main properties of an AC: the amplitude, the frequency, period and the phase angle. The amplitude is the peak point of an AC that dictates its maximum and minimum voltage value at any point in time. In the example, the amplitude is 10V, so the voltage swings from +10V to-10V. The period is the time for an AC to complete one cycle. For every one period, the AC repeats the waveform pattern. The inverse of period is the frequency. Frequency is the property of an AC that numerically counts the number cycles the AC will perform for one second. Lastly, the phase angle is the property ...