Sunday, March 17, 2013

What is alternating current and direct current?

                        What is alternating current and direct current?

Electricity flows in 2 ways --- either as alternating current ( AC  ) or as direct current ( DC ).  Electricity or current is nothing more than the moving electrons along a conductor , that has been harnessed for energy . Therefore , difference between AC and DC has to do with the direction in which the electrons flow . In DC , electrons flow steadily in a single direction or forward . But in AC , electrons keep switching directions sometimes going forward and then going backwards.
Because of this , the frequency of AC is generally 50 Hz whereas the frequency of direct current is zero .The source of AC could be a AC generator or mains . But for DC , it is battery . Passive parameters of AC is impedance which consists of resistance , inductance and capacitance. But for DC , it is resistance only .
Power factor of AC lies between 0 and 1.
But for DC , it is always 1.
Why does the current flows in a single direction in DC ? A magnetic field near a wire causes electrons to get attracted towards positive side and get repelled towards negative side , thus flowing in a single direction steadily.
But AC is safer to transmit over a long distance and can provide more power. Instead of applying the magnetism along the wire steadily , the direction of magnet is changed periodically so does the direction of electrons as well.
But DC can be stored like in batteries but we can not store AC.

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