18 Difference between AC and DC Current [Alternating vs Direct]

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In my earlier electrical current tutorial, I shortly explained alternating current and direct current.

Here, I am describing the multiple specifications of both alternating current (AC) and direct current (DC) with the help of the diagram. Also, we will see AC vs DC.

What is the difference between AC current & DC current?

Here is the difference between the alternating current vs direct current specified in tabular form.

# Contents Alternating Current Direct Current
01
Representation
AC represents as Alternating Current. DC represents Direct Current.
02 What is alternating current & direct current? In an electrical and electronic circuit, the current which flows in both directions (with positive and negative lead) at a constant frequency is called ‘Alternating Current’. In an electrical and electronic circuit, the current which flows only in one direction (with positive lead) is called ‘Direct Current’.
03 Current AC flows in a bidirectional way. DC flows in a unidirectional way.
04 Voltage It works on the AC source voltage 110V, 240V, 11kV, 33kV, etc. It works on DC source voltage 5V, 12V, 24V, etc.
05 Power AC source produces real (P) power and reactive (Q) power. DC source produces only real (P) power.
06 Frequency AC has a variable frequency. Usually, it varies from 50 Hz or 60 Hz. DC has zero frequency. This current doesn’t flow with the frequency.
07 Direction & Magnitude

(Details in 14 no. point)

The direction and magnitude of AC are always varying with time. The direction and magnitude of DC are constant with time.
08 Resistive For limiting AC, reactance (X) or impedance (Z) are used. For limiting DC, only resistance (R) is used.
09 Types AC is classified into different types- Sinusoidal, Trapezoidal, Triangular, Square, etc DC is classified into two types- Pure, Pulsating.
10 Power Factor In the AC circuit, the power factor is always from zero (0) to one (1). In the DC circuit, the power factor is always unity (1).
11 Waveform AC wave occurs in the leading or lagging position. DC wave occurs in a straight forward position.
12 How current is generated? AC source is produced by the generator or power generating plant. DC source is produced by the cell, battery, and solar cells.
13 Ohm’s Law The AC circuit does not obey ohm’s law. DC circuit does obey ohm’s law.
14 Used It is used in domestic, commercial, and industrial purposes. It is used in the electronic circuit and DC appliances.
15 Transport AC can be easily transferred to the long-distance by using the transformer. DC cannot be easily transferred to the long-distance.
16 Maintenance It can be easily regulated and maintained. It can’t be easily regulated.

17. Symbolic Representation of AC and DC

  • Alternating Current (AC) Symbol:

Alternating current (AC) symbol

  • Direct Current (DC) Symbol:

Direct current (DC) symbol

18. The waveform for AC and DC

  • AC Waveform:

The alternating current (AC) waveform occurs in the sinusoidal in nature. Sinusoidal AC wave always varies with time at a constant frequency (50Hz or 60 Hz). You can see in the below alternating current graph.

It flows through the positive phase (+ve terminal) to the negative phase (-ve terminal) with varying frequency and time.

Single Phase System

Bi-directional AC Waveform

Mostly, 50 Hz or 60 Hz frequency is used for domestic, commercial, and industrial purposes.

  • DC Waveform:

DC waveform occurs in the straight forward and constant in nature. Due to its constant nature, the waveform varies with time in a continuous steady-state direction. You can see in the below direct current graph.

DC doesn’t require the frequency to flow in the circuit. DC is flowing in a unidirectional way (positive terminal) with the time period.

Direct current waveform

Uni-directional DC Waveform

I have covered most of the difference between alternating current and direct current with the help of specifications, symbols, and graphs.

Here are some more differences you would like to read:

Hopefully, while going through the difference between AC and DC current, you have cleared your doubts.

If you have any queries or if there is any point you want me to explain, freely drop the comment in the below section.

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3 thoughts on “18 Difference between AC and DC Current [Alternating vs Direct]”

  1. In the AC circuit, the power factor is always zero (0) or unity (1). My opinion that, PF is between 0 until 1, not 0 or 1.

    Reply

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