DIRECT CURRENT (DC):
Direct current is the electricity flowing in a constant direction, and/or possessing a voltage with constant polarity. It can be expressed in terms of just two variables: polarity (or direction), and magnitude. It is the current that always flows in the same direction, and that does not change in intensity with time. DC is the kind of electricity made by a battery , or the kind of charge generated by rubbing certain types of materials against each other. Batteries and other sources of direct current (dc) produce a constant voltage. This can be represented by a straight, horizontal line on a graph of voltage versus time.
ALTERNATING CURRENT (AC):
In alternating current, the polarity reverses again and again at regular intervals. The magnitude usually changes because of this constant reversal of polarity, although there are certain cases where the magnitude doesn't change even though the polarity does. The rate of change of polarity makes ac so much different from dc. The length of time between one repetition of the pattern, or one cycle, and the next is called the period of the wave. frequency is the cycles per second and is denoted by f, which is the reciprocal of the period. That is, f = 1/T and T = 1/f .unit of frequency is hertz (Hz)
Alternating current (AC) waves are of different types; Such as sine wave, square wave,sawtooth waves,complex and irregular waveforms etc.
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