• Poornima Mani

Alternating Current vs Direct Current

Updated: Dec 1, 2020

Current is the soul of any circuit, be it lighting a bulb or managing an entire city. But there are mainly two kinds of #current that show totally different properties and should be understood by every person involved in the domain of electronics. Let us first understand the difference between the currents, then their comparison, and lastly, their applications.

But before that, do you want to know how the reason and history behind the names and concepts of AC and DC? Let us right away jump into it.

Direct Current, as the name implies, has current flowing only in one direction. Alternating Current, on the other hand, has electric charges, changing its direction periodically and voltage also changes its direction correspondingly.


AC: AC generation is satisfied by converting one form of energy to another; specifically, mechanical energy into electrical energy. Faraday’s law of electromagnetic induction is the principle behind AC generators and current is achieved by rotating a coil in a uniform magnetic field or by rotating the field itself with a static conductor. The EMF generated after this process is dependent on the turned in armature coil, field strength, and rotating field's speed.

The major components include Field, Armature, Prime Mover, Rotor, Stator, and Slip Rings. As the armature rotates, flux linkage is constantly changing and the emf induced generates a current. This current seen in the galvanometer is Alternating Current and the direction can be identified using Fleming’s Right Hand Rule.

DC: A DC generator converts mechanical energy into electric energy for producing current. In this system also, the emf is generated by the principle of Faraday's law and allows current to flow in a closed circuit.

A DC generator has the components: Stator, Rotor, Armature Windings, Yoke, Poles, Pole Shoes, Commutator, and Brushes. When a current-carrying conductor is kept in a changing magnetic field, an emf is induced in the conductor. By using Fleming’s right-hand rule, we can understand the direction of the induced current.

Assume that the armature is rotating in the clockwise direction and a conductor is moving upwards. When half a rotation is complete, the direction is reversed downwards. This is when the split ring commutator comes into play to reverse the current direction. Thus, we always get unidirectional current or simply Direct Current.


The DC plot is a straight line as shown because the magnitude is the same through and doesn't change with time.

Unlike this, an AC waveform has the magnitude changing every second and is called "bi-directional" as it has both positive and negative values.

Differentiation between AC and DC

Given below are some of the most common differences between Alternating Current and Direct Current.

Applications of AC and DC

AC is extensively used in transportation and production of electricity. Households are fully supplied with Alternating Current. AC is popularly used in home appliances, electric motors et where there is a direct conversion of energy.

AC Power Supply

DC or Direct Current is involved in batteries, adapter, chargers, and hybrid cars. They are popular in cellphones, TVs, and many other applications.

Mobile charger and adapters

This was just a peek into the deep topics of Alternating and Direct Currents. Check out the other articles too.

See Also:

  1. Resistors and Resistances

  2. Interfacing LCD with Raspberry Pi







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