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What is the difference between AC and DC?

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  • 3 min read

Electric current is the rate of flow of electric charge from one point to another. This current is of two types, AC and DC. Both the currents have their respective uses and are necessary for normal functioning of the electrical grid.

In this article, we explain the difference between an alternating and direct current, which have been compared on some fundamental parameters.

Alternating Current(AC)

In Alternating Current, the electrons change their flow continuously due to the rotating magnetic field in which the current travels. This rotating magnetic field causes the electrons in the current to attract towards respective poles. When the magnet is rotated, the particles change the poles, hence the direction change. In case you want to understand this process in a simple manner, plot this current on a graph. On the X-axis, mark the voltage and on the Y-axis, mark the time.

Alternating current is transferred via the electric poles

Now, the alternative current will look like a wave going from one point to another. The crest, which is the top point of the wave, shows that the current moves upward while the trough, which is the lowest point of the wave, depicts the current’s backward or negative movement.

You can increase or decrease electrical energy with the help of a transformer. This is of particular help when you transmit high voltage across a significant distance as this reduces the power loss. Usually, the power is generated at around 50 to 60 Hz depending on the country.

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Direct Current(DC)

On the other hand, Direct Current transmits the electrons in a single direction as it is placed in a static field. The direct current can transfer through a medium such as a wire and a vacuum in the form of electron beams. This current remains constant with time and cannot be increased or decreased, as is the alternating current.

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Batteries are an example of direct current

However, DC cannot be used for long-range transmissions as it looses the electric power when transferred over long distances. While the AC has a frequency of around 50 to 60 Hz, DC has no frequency as it is constant.

The example of DC generators are cells, batteries, solar cells, among others.

Converting from AC to DC and vice versa

Alternating current can be converted to a direct current via the help of an adapter (power brick). Similarly, DC can be converted to an AC via the invertor.

Here is a table comparing AC and DC on a few parameters.

CategoryAlternating Current (AC)Direct Current (DC)
Direction of CurrentBi-directional (changes direction frequently)Unidirectional
50Hz to 60 Hz

No frequency
Power FactorLies between 0 and 1
Always 1
Voltage Magnitude
Transmission Length
Can be transmitted over long distances

Cannot be transfered over long distances

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Kumar Hemant

Kumar Hemant

Deputy Editor at Candid.Technology. Hemant writes at the intersection of tech and culture and has a keen interest in science, social issues and international relations. You can contact him here: