Difference Between AC And DC

Download PDF

Comparison Between AC And DC Motor

Electric current flows either in one direction or keeps changing its directions periodically. Hence, there are two ways of current flow, namely; alternating current (AC) and direct current (DC). The major difference between AC and DC is that current electricity flows gradually in one direction in the direct current (DC). However, current continuously varies its direction from forward to backwards and vice versa. Learn more about the points that distinguish between AC and DC. 

What is an AC Current?

The term AC refers to Alternating Current in Physics, which is highly preferred electric power for office, household equipment, and more. The critical difference between alternating current and direct current lies in the direction in which electric charges flow. In AC, electrons continuously change their directions from forward to backwards periodically.

The curve of an alternating current when drawn on a graph represents the sine waveform. The curved lines denote electric cycles that are measured per second. As compared to DC current, it’s easy to generate and transport AC across large distances. Hence, alternating current is widely used in buildings, powerhouses, and more. 

What is a DC Current?

DC refers to direct current in which there is no change in the direction of current flow. Hence, the major difference between AC and DC current is the electric current flows only in one direction in a stable voltage in DC current. One of the major uses of DC is to charge batteries and supply power for electrical devices. In the DC circuit, electrons emerge from the negative side and move towards the positive side. The basic source of DC is produced by photovoltaic cells, batteries, or electrochemical cells.  

The above image shows that direct current flows in one direction. The graph shows the proportionality between the magnitude of DC and time.

Anything that uses an AC adapter while plugging into a wall or that runs on a battery depends on direct current. Some of the examples of DC include flashlights, mobile phone batteries, electric vehicles, and more. By going through with the difference between AC current and DC current, it’s easy to understand why AC is most referred across several applications. 

How Alternating Current is Converted into Direct Current?

There are several cases when there is a necessity to convert AC into DC. It’s because of the AC and DC difference that direct current is less preferred over long distances. To convert AC into DC, the power supply that consists of a transformer is required. Later it gets converted into direct current with the help of a rectifier. The conversion of AC into DC is beneficial to prevent the flow of current from reversing. A filter used eradicated the current pulsations in the rectifier output.

Differentiate Between AC and DC Current 

To sum up, the points of difference between AC and DC include:

Points of Difference

Alternating Current (AC)

Direct Current (DC)

Travelling Distance

It’s safe to transfer alternating current over long distances and maintain electric power. Even it can transfer between two cities. 

From the compare AC and DC current, it’s found that DC cannot travel for far distances. It’s because DC loses electric power.

Electron Flow

In AC, electrons keep switching their direction from frontward to backward.

Electrons only move in a forward direction in a DC motor.


The frequency of the alternating current is generally in between 50 to 60 Hz. Moreover, it’s frequency depends upon the country.

The direct current has no or zero frequency. 

Source of Availability

The source of availability for AC current is AC generators.

The source of availability for DC current is either battery, electrochemical cell, or photovoltaic cell.


Generally, AC current is of sinusoidal type. Its other types can be triangular and square trapezoidal.

The DC current is of pure and pulsating form. 

Flowing Direction

There is a change in the direction of the current electricity flow due to the rotating magnets.

The direct current flows in a single direction due to steady magnetism. 


From the AC current and DC current difference, it can be said that AC is capable of powering electric motors used on washing machines, refrigerators, and so on.

The direct current is preferably used in cellphones—flat-screen TVs, and so on.

Loss of Energy

As compared to DC, the loss of energy during the transmission in AC voltage is low.

DC involves a high loss of energy and hence not preferred when transformers are at a distance. 

FAQs (Frequently Asked Questions)

1. What do you mean by the Universal Motor?

Ans: A universal motor can run both on both DC and AC supply. The name suggests these motors are universal that work with high torque and have different speed features. These motors use electromagnets as the stator that produces a magnetic field. These motors are generally lightweight and compact and work at a high speed. Usually, it is used in household appliances and featured with portable power equipment and tools. You can easily control and operate them with its tapped coils. 

2. What are the examples of AC and DC?

Ans: AC defines alternating current and DC is defined as direct current. Usually, these currents are referred to with the voltages. Everything that is powered with the battery and operates on an AC adapter uses DC current. Such appliances are cell phones, flashlights, vehicles, TVs etc. However, AC cannot be stored in the batteries as these do not supply energy because of changing polarity. In AC, the positive half will cancel out the negative half, which can damage appliance battery with time. Hence the final conversion is made to DC current. 

Share this with your friends