Alternating and direct current (2024)

Current is harnessed in two main forms: Alternating and direct current. These two are the modes of current and each has its characteristics.

The movement of electric charges creates current so the current is the flow of electric charges. The current is divided into two types: Alternating and Direct current. In the direct current, the electric charges flow in one direction, and in the alternative current, the flow of electric charges periodically reverses its direction.

In this article, we’ll learn about both forms of current in detail and will also discuss their applications.

Electric current

Electric current is the rate of flow charges within the conductor when external voltage or potential difference is applied.

The flow of electric current is divided into two types: Alternating and Direct current.

The major difference between these two types is the direction in which charges flow.

1. Alternating current (AC)

Alternating current which is also known as AC. In AC the magnitude and direction of current change periodically and continuously with time.

Periodically means it will repeat itself after an equal interval of time. Let’s explain this thing with an example of a water pipe with a piston that moves backward and forward.

In the above setup, there is a piston that is connected to the rotating rod, this piston moves in two directions: forward and backward.

When the piston is in a forward direction the water in the pipe flows clockwise. When the piston is in the backward the water flows anticlock.

In this way, the process will repeat itself continuously after equal intervals of time. The same process is with AC.

Now see the AC time graph. From this, we’ll understand how it periodically changes magnitude and direction.

From the above graph, you can see that the current started increasing from zero means charged particles started moving.

Gradually increasing and reaching a positive maximum, and after that, it gradually decreased and became zero completing a positive cycle.

Now the charged particles will reverse their direction and again increase from zero but in the opposite direction.

In this way, after reaching a negative maximum it will become zero and a complete negative cycle. In this way, the same cycle repeats itself again and again.

Characteristics of AC

Let’s discuss some characteristics of alternative current.

Time period: The time period (T) is the total amount of time that a waveform takes to repeat one cycle or to repeat itself.

Another way to put it is that the time period is the whole amount of time the waveform takes to complete one full cycle.

Frequency: The reciprocal of the time period is called frequency. Frequency can be defined as the rate at which a waveform repeats itself, or simply as the number of times the waveform repeats in a second. Its unit is Hertz and can be given by,

f=1/T

Here ‘T’ represents the time period of the AC waveform.

Amplitude: The magnitude of the AC signal is called the amplitude of the signal. It is the maximum value that the current reaches during one complete cycle. So, if the amplitude is higher, the current is stronger.

Applications of AC

Here are some of the key applications of AC:

Power distribution: The distribution of electrical power is one of the most important uses for AC. The electricity we use in our house is AC.

It is transmitted from power plants to residences, commercial buildings, and industrial facilities via AC.

Because of its effectiveness in long-distance transmission, it is the norm for power networks all over the world.

Household appliances: For home appliances to function we need current. AC power is used for lighting, heating, cooling, running appliances, and charging electronic devices.

Industries: Powering industrial machinery and equipment is a common usage for AC. It supplies the energy required to run various production processes, motors, pumps, and conveyor belts.

Electronic devices: AC power is necessary for the operation of audio and video equipment, including stereos, televisions, radios, and home theater systems. In broadcasting, AC is also utilized for signal transmission.

AC electricity is necessary for the operation of computers, servers, and data centers. These devices’ power supplies frequently convert AC to DC for internal use.

These are just a few applications of alternative current.

With its capacity to efficiently transform to other voltages and frequencies, as well as its ease of distribution, it is a versatile and frequently used kind of electric power in a variety of fields.

2. Direct current (DC)

The direct current which is also known as DC is the type of current that is unidirectional. It doesn’t change its direction and magnitude.

As the direction and magnitude of DC are not changing DC has a frequency equal to zero.

Let’s take a water analogy, there is a water tank filled with water and at the end, it has a pipe with a valve.

When we open the valve the water starts flowing in one direction. The flow of water can be stopped by closing the valve but we can’t reverse its direction.

The same is true with direct current, its direction can not be reversed; it will flow in only one direction.

When we consider the current-time graph of DC it will always be a straight line which means the flow of charges or current is not changing its magnitude and direction with time.

Characteristics of DC

DC has several characteristics, here are the key features of DC.

Unidirectional: As AC changes its direction but the DC flow flows in one direction, from the positive terminal to the negative terminal.

Constant current/voltage: In a DC system, the voltage and current remain steady over time, without changing direction or magnitude. If you see the current-time graph of DC, it is a straight line which means the current and voltage are constant.

Polarity: DC circuits have fixed polarity, meaning the positive and negative terminals remain the same, which affects how electronic components are connected.

Applications of DC

Here are some of the most common DC applications.

Batteries: The most well-known source of DC power is probably batteries. They’re found in everything from small consumer electronics like smartphones and laptops to larger applications like electric cars and uninterruptible power supplies (UPS).

Electronics: Many electronic devices and components, such as integrated circuits, microcontrollers, and sensors, require a consistent DC power source to function. DC power is utilized to supply the voltage and current required by these devices.

Some applications require LED (Light emitting diode) that operate on low voltage so the DC power is suitable for it. Every electronic circuit needs DC to operate and perform as intended.

It is also used in the electroplating process, which is a process that involves depositing a layer of metal onto a surface to improve its appearance or protect it from corrosion.

Automobile: DC power is used in a variety of automotive applications, including starting and charging systems in internal combustion engine vehicles. It is also used for high-voltage traction batteries and auxiliary systems in electric and hybrid vehicles.

Telecommunications: Many telecommunications equipment and infrastructure components, particularly in rural and off-grid regions, are powered by DC. DC power is more dependable and efficient for these applications.

DC power plays a crucial role in providing stable and reliable electrical energy for a wide range of devices and systems across various industries.

Difference between AC and DC

Alternating Current (AC)	Direct Current (DC)
AC is safe to travel power over longer city distances.	DC loses energy so it can’t be used to transfer power over longer distances.
The AC cannot be stored.	DC can be stored in batteries.
The frequency of AC is between 50Hz to 60Hz depending upon the country.	The frequency of DC is zero.
The AC reverses its direction while flowing in the circuit.	The DC is uni-directional means it flows in one direction.
The magnitude of AC varies with time,	The DC magnitude does not vary with time.
In AC, the charges change their direction.	The charges don’t change their direction in direct current.
The AC can be obtained from a generator or mains.	The DC can be obtained from a cell or battery.

Conclusion

Current is the rate of flow charges. Depending on the charge flow the current is divided into types: Alternating current (AC) and Direct current (DC).

AC is the type of current in which the flowing charges reverse their direction periodically or we can say that the magnitude and direction of current are changing with time.

It is used to transfer power to houses, and industries and charge different electronic devices.

In DC, the charges flow in one direction. So the magnitude and direction of the current remain constant with time. DC can be found in batteries and to power electronic circuits and components DC power is utilized.

That’s it, this was all about alternating current and direct current. I hope you have found it interesting.

Thank you and stay blessed…