# Difference between AC and DC

Last Updated on January 23, 2023 by Electricalvolt

This article describes the key differences between AC and DC. But before knowing the AC vs DC, first, we will learn the basics of electric current and its types namely alternating current and direct current individually for a better understanding of the differences between alternating and direct current.

The term electric current is defined as the continuous flow of electric charges or electrons between two given points across a conductor. Since its discovery in the early 1800s, the electric current has proved its importance in the world of electricity. And, now, electricity has become an essential part of our life. Based on the characteristics of electric current, it is broadly classified into the following two categories,

• Alternating Current (AC)
• Direct Current (DC)

## What is Alternating Current (AC)?

Alternating current is defined as the type of electric current which changes its magnitude alternately between positive and negative values and its direction at fixed periodic intervals, throughout its time period.

The abbreviated form of alternating current is AC. Alternating current is used for long-distance transmission of power from power stations to residential areas due to its capability of converting from high voltage to low voltage values, thus taking into account safety issues. Additionally, the use of AC reduces the losses incurred in AC generators and motors and increases their efficacy and performance.

Alternating current is also described as the total number of cycles completed in one time period as shown in Figure 1. The time period is the time taken by a sinusoidal wave to complete one cycle. While frequency, which is also the reciprocal of the time period, is defined as the number of cycles generated by the alternating current waveform per second. The time period and frequency of the AC waveform are related by the following formula:

Depending on the shape of the alternating current waveform, AC can be of the following types:

• Sinusoidal wave
• Triangular wave
• Square wave
• Saw-toothed wave

## What is Direct Current (DC)?

Direct current is described as the unidirectional flow of electric current across a conducting wire. In other words, direct current shows no fluctuations in direction or magnitude across the entire time period for a particular type of load, i.e. its magnitude remains constant across the entire time interval for a specific circuit and, the direction of current does not change.

The abbreviated form of direct current is DC. This means that the frequency, i.e. the number of fluctuations of the current per second is zero, as DC is just a straight line at a fixed value of current as shown in Figure 2. Direct current is used in various battery-operated devices such as PC, laptops, cell phones, remote control toy cars, etc. requiring short-distance transmission of power.

Depending on the nature of the DC waveform, it can be of the following two types:

• Constant DC – This type of DC current is the desired form of direct current con summed by various electronic devices where the current remains stable or the same.
• Pulsating DC – This type of DC current is utilized in most Pulse width modulated (PWM) device controllers, where there is a slight fluctuation in the DC signal, which can be smoothed out by using certain types of filters.

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

The table below lists the important differences between alternating current and direct current –

### Conclusion

In conclusion, this article describes the major differences between the alternating and direct current flow in electronic devices and how they are utilized for a variety of commercial and domestic purposes. The most significant difference between them is that AC involves the bidirectional flow of electric current, while DC involves the unidirectional flow of current. Overall, both AC and DC play an important role in the operation of various electric power systems. 