Types of Electric current

Electric current is further divided into two based on the flow of electric charge i.e, Alternating Current (AC) and Direct Current (DC).

Dc Current: The current that flows continuously in a single direction at a constant rate is Direct current (DC). In a closed electric loop, all electrons flow in one direction around the loop. It means there is no change in polarity and remains constant all the time. The frequency of dc current is zero since it flows in only one direction. The figure below shows the waveform of the Dc current.

Dc power is usually used in low-voltage electronics applications. Batteries, fuel cells, solar cells, thermocouples etc are some examples of dc power supply. Mobile phones, radios, watches etc used dc current.

Ac Current: The current that changes its polarity back and forth when flowing in a circuit is known as alternating current (ac current). The back and forth change in direction results in frequency and is expressed in Hertz. The frequency of Ac current depends upon the standard of the country’s appliances.

For example, the frequency of Ac current in the US is 60Hz whereas the frequency of Ac current in Australia is 50Hz. This means that the direction of the current is changing 50 times per second. The figure below shows the waveform of the Ac current.

The waveform of AC current may be sinusoidal, square, triangular etc. Generation of electric current is done by an alternator. Ac electric power is widely used in all types of household as well as industrial equipment ranging from electric bulbs to big electric motors.

Let’s see the difference between AC Current and DC current.

AC vs. DC

In terms of	Alternating Current	Direct Current
Frequency	It has frequency of 50-60Hz	Its frequency is 0 (no oscillation).
Direction	Change its direction.	Always flows in same direction.
Current Magnitude	Its magnitude varies with time.	Its magnitude is constant throughout.
Power Transmission over Large Distances	Bulk power transmission with low losses.	More power loss in terms of the large distance.
Efficiency	It has greater efficiency than dc.	It has less efficiency than ac.
Safety	It has Higher voltage – not as safe	It has Lower voltage – safer
Generation	It is generated by Rotating magnets	It is generated by Steady magnetism.
Availability	Power plant (Hydro, coal, wind)	Batteries, solar power, thermocouple.
Types	Its produces Sine wave, square wave, etc.	It is Continuous or pulsing.