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Difference between AC and DC Current

Electrical current flows using two ways: either in a direct current or in an alternating current (AC). Electric current is basically the free movement of electrons by a conductor. The main difference between AC and DC is based upon the direction in which the flow of electrons occurs.

DC Current

Current that flows continuously in one direction is termed directed current (abbreviated dc). This is the kind of current supplied by a voltage cell. Because the voltage at the terminals of a voltage cell does not reverse the polarity remains substantially constant, a voltage cell can be termed as a direct voltage source.

Direct Current

Fig.1: Direct Current

AC Current

Alternating current (abbreviated ac) is current that flows first in one direction for a brief time and then reverses to flow in the opposite direction for a similar time. Alternating current is created by utilizing a device known as an alternator. This is a specialized type of generator constructed to generate alternating current.

AC Current

Fig.2: AC Current

The major benefit that alternating current offers for the power system is that it is comparatively simple to alter the voltage of the power, using a device known as a transformer. Electric companies are saving a lot of money this way, employing very high voltages in order to carry power across long distances.

The key differences between AC current and DC Current are discussed here on the basis of direction, source, frequency, load type, storage, conversion, power factor, severity, and applications.The following table presents the key differences between AC Current and DC Current.

Difference between AC Current and DC Current

Characteristics Alternating Current (AC)Direct Current (DC)
OriginatorNikola TeslaThomas Edison
DirectionDirection of current changes periodically (Bi-Directional)Current direction remains the same (Uni-Directional)
Frequency Either 50 Hz or 60 Hz mainly depends upon the locationZero Hz
SourceProduced by AlternatorsProduced by generators, cell, and batteries
Load TypeResistive, Inductive, and Capacitive loads run by ACONLY resistive loads run by DC
Power Factor (Cos 𝛉 )Ranges between 0 and 1 (because of phase angle difference between voltage and current)Remains 1 because of ONLY resistive load (since voltage and current are in phase)
RepresentationCan be represented by Square wave, Sine wave, Triangular wave, and Saw-tooth waveIt is represented by the straight line ONLY
StorageCannot be stored (dynamic entity)Can be stored in batteries & cells
ConversionIt can be converted into DC easily using RectifierIt can be converted into AC (with some operational complications) using Inverter
Cause of electrons flowRotating magnet along the wireSteady (constant) magnetic field along the wire
TransmissionIt can be transmitted, with certain losses, over long distancesCan be transmitted, with trivial losses, over long distances (favorable for long distance transmission)
SeverityDangerousExcessively dangerous
Substation Requirement Requires very few substationsMore substations are needed
ApplicationIt is commonly used in Houses, Industries and FactoriesIt is generally used in Electronic components, Electrolytic process , and Electroplating process


AC can be converted to DC by utilizing a device called an adapter that can be used to power up the laptop battery. On the other hand, DC can be changed to AC using a device called an inverter but its little complex in operation. For instance, an inverter changes 12 V DC into 120 V AC in order to run some small devices.

About Ahmad Faizan

Mr. Ahmed Faizan Sheikh, M.Sc. (USA), Research Fellow (USA), a member of IEEE & CIGRE, is a Fulbright Alumnus and earned his Master’s Degree in Electrical and Power Engineering from Kansas State University, USA.

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