The main important difference between AC and DC

Difference between Alternating Current(AC) and Direct Current(DC)

The main difference between Alternating Current(AC) and Direct Current(DC) is that in the case of AC the direction of the flow of current changes with time but in the case of DC the direction of the flow of current not changes with time.


Another important difference between AC voltage and DC Voltage is that in the case of AC the polarity of the voltage changes with time but in the case of DC the polarity of the voltage not changes with time.



We have two types of electric supply one is in the form of Alternating Current(AC) and the other is Direct Current(DC). Both the AC and DC have advantages and disadvantages. We needed both AC and DC. In this post, we will discuss the main important difference between AC and DC.

 A lot of differences can be written but you should know the main difference because the whole electrical and electronics engineering depends upon the AC and DC.

I have noticed that most of the students do not understand various topics of electrical and electronics engineering due to the lack of proper knowledge of AC and DC. So I have tried to convince you easily the main difference between AC and DC.



AC means alternating current and DC means Direct Current so the actual concept of AC and DC is dependent on the Current.

In simple words, the Current is the flow of electrons through the conductor. If you See all the below figures you will understand the difference between AC and DC easily. Of course, I will help you. So let's go.

What is DC(Direct Current)?

As you see in the above figure the circuit has an electric supply and a Load. The two terminals of the electric supply source are denoted by 'A' and 'B'. Now let's assume that the A terminal is positive and B terminal is negative.


 If the A terminal is always positive and the B terminal is always negative then it is called a DC source because as the polarity does not change, the current will be flowing in one direction only from positive to negative or A to B. As the current does not change its direction it is called Direct Current or DC.
So if the direction of the current flowing from source to load does not change with time then it is called Direct Current but remember that it may be pure DC or Impure DC or Pulsed DC.



Now it is clear that in the case of DC, the current does not change its direction, but voltage? If the magnitude of the voltage of the DC source is changed with time then it is called impure DC.

As you see in the above figure the pulse wave represents that the magnitude of the voltage changes with time some time Zero(0) volt and some time Five(5) volt.
So a Pure DC does neither change the direction of current nor magnitude of the voltage.


Read Also: Which is more dangerous AC or DC-Explained in details

What is AC(Alternating Current)?

As you see in the above figure the circuit has an electric supply and a load. The two terminals of the electric supply source are denoted by 'A' and 'B'. Now let's assume the A terminal is positive and B terminal is negative. 


After some time the A terminal becomes negative and the B terminal becomes positive and again after some time the A terminal becomes positive and the B terminal becomes negative. So if the interchanging is continued, then the direction of flow of current from the source to the load will be changed and the changing of direction also be repeated and it is called Alternating Current or AC.

So it is clear that in the case of AC, the direction of the flow of current changes with time as the source changes it polarity with time.
If the voltage is constant but the direction of the current is changing then it is called Pulsed AC. The pure sine wave AC changes the direction of the flow of current and also the magnitude of voltage with time.

Read Also: Why we use 220V, 50Hz AC at home instead of DC or other voltage?Full Explanation.


The other differences between AC and DC are given below,

Alternating Current(AC) VS Direct Current(DC):

Serial No.	Alternating Current (AC)	Direct Current (DC)
1.	The direction of the flow of current changes with time.	The direction of the flow of current not changes with time.
2.	AC has the frequency.	DC has no Frequency.
3.	In the case of AC, the power factor lies between 0 to 1	In the case of DC, the power factor is always 1
4.	AC cannot be stored.	DC can be stored in the battery.
5.	AC can be generated from an AC generator or alternator.	DC can be generated from a DC generator, Solar Cell.
6.	AC has phase and neutral	DC has Positive and negative
7.	The efficiency of AC is high.	The efficiency of DC is low.
8.	AC can be stepped up or Stepped down by the transformer.	DC cannot be stepped up or stepped down by the transformer.
9.	AC may be single-phase or polyphase	Only single-phase DC is possible.
10.	The inductor can block AC	The inductor cannot block DC
11.	A capacitor gives low reactance on AC	A capacitor gives high reactance on DC
12.	Effect of Impedance and resistance both possible in AC	Effect of resistance only possible in DC
13.	In the case of AC, there may be some angle between voltage and current.	In the case of DC, the angle between voltage and current is always Zero (0).
14.	The heating effect of AC is less than DC for the same voltage.	The heating effect of DC is more than AC for the same voltage.

Read Also:

• Difference between Generator and Alternator Full explanation. 
• Three Reasons Why Transformer Ratings in KVA.

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