AC and DC

Alternating Current and Direct Current

Alternating Current (AC)

It is a current whose magnitude changes continuously and direction changes periodically.

The source of AC is AC generator.

In India mostly current is supplied in AC form. The frequency of AC in India is 50 Hz. It means AC changes direction every 1/100 of a second. In complete cycle of AC, it changes its direction twice.

Direct Current (DC)

It is a current whose magnitude is always constant and such a current flows in one direction only.

The source of DC are DC generators, cells, batteries etc

Advantage of AC over DC

1.  An alternating current (AC) can be transmitted to long distances without much power loss where as if direct current (DC) is supplied to long distance that most of its energy is wasted in the form of Joule’s heat.

2.  An alternating current (AC) can be step-up and step-down i.e. the voltage can be increased or decreased with the help of transformers whereas a DC can not step-up or step-down.