What is direct current and alternating current? Distinguish between direct current and alternating current. What is AC? What is DC? What is AC Current? What is DC current? What is the difference between AC and DC electricity or the difference between direct current and alternating current? What is the practical application of direct current & alternating current?
Surely we have heard of the concept of direct current – alternating current. Or we see the letters AC, DC on household electrical appliances such as refrigerators, televisions, washing machines, light bulbs…. So what does AC, DC stand for and what does it mean? What are the characteristics of direct current and alternating current? It is one of many questions that very few people can answer.

Phân Biệt Dòng Điện Một Chiều (DC) Và Dòng Điện Xoay Chiều (AC)


AC power is used a lot and is very familiar in our daily life. Direct current is also more commonly used. So, how can you distinguish and understand which is DC and which is AC? In today’s article, I will introduce you some basic knowledge about these two types. From there, I will help you distinguish between AC, DC and practical applications.

What is direct current and alternating current?

What is direct current (DC)?

Direct current is denoted as DC (Direct Current). Simply put, DC is a current that flows in a fixed direction. It can increase or decrease in strength, but it does not change direction. Direct current is an AC current.

We can encounter DC current in devices such as batteries, cell phone chargers, and accumulators ….. For direct current, there will be negative (-) and positive (+) symbols on devices that contain direct current). . In addition, we have heard of DC voltages such as. 5vdc, 12vdc, 24vdc …. Some characteristics of DC, such as.

Amperage can increase or decrease, but it does not change direction

The direction of current is usually from positive to negative

DC is generated by batteries, accumulators, and solar energy.

What is alternating current (AC)? The concept of DC and AC

AC is alternating current. A type of current whose direction and magnitude vary with time, usually with a definite period. This means that AC in a circuit flows in one direction and then the other. When we talk about alternating current, we often mention: frequency and period.

Most household appliances today use AC power, such as: air conditioners, refrigerators, washing machines, electric stoves, televisions, fluorescent light bulbs, etc. Alternating current is usually represented by the letters AC or tilde (~).

Distinguishing between direct current and alternating current

After learning about direct current and alternating current and understanding their basic characteristics. Next, let’s summarize and compare these two basic types of currents. Some basic differences between AC and DC currents are as follows.

Power source (AC is a generator, DC is a battery.)

Current direction characteristics (AC can be reversed, while DC has only one direction)

Symbols (AC stands for ~, while DC stands for +,-)

Phase and frequency characteristics (AC has period, frequency, phase, DC has no phase)

In addition to the above characteristics, when using DC-AC power, we should also pay attention to the degree of safety when using it. Direct current or alternating current are potentially dangerous to human life. Therefore, let’s learn how to use electricity safely together.

Dangers of DC and AC Electricity

Many accidents with electricity occur every year, and the number of people who die from electrical accidents is increasing. Both direct current and alternating current have the potential to cause death. When the environmental conditions are wet and the amperage is high enough, it can cause death. As we can see in the table above, the degree of impact on the human body varies depending on how many milliamperes (mA) of current are present.

Another parameter is the time that the current acts on the human body, which is also an important parameter. As in the table above, we see that for a current of 1A, a paralysis of the heart can be caused when it runs in the human body for 25ms. As you can see, very fast times and very low currents can also be fatal.

Therefore, we need to ensure absolute safety when using equipment with DC & AC power. It is recommended to use automatic circuit breakers at home to cut off the power in time.

AC to DC Converter – AC to DC

After we have distinguished what is AC and what is DC, do you wonder if there is any device that can convert between AC and DC? Of course, there is a device that can do this. Because we know that not all devices use AC power, there are some devices that can only use DC power. The most obvious one is your laptop. In addition to laptops, there are Wifi modems, cell phone chargers, Bluetooth speakers ……

The device that converts AC power to DC power is called a rectifier. When we talk about rectifiers, we immediately think of diodes. A diode is a semiconductor device that allows electricity to flow in only one direction. Using this feature, people connect diodes to form a rectifier bridge that converts AC to DC. This is the basic principle of the rectification process that forms direct current from alternating current. In fact, the rectifier circuit must have other components, such as capacitors, resistors, transformers, etc.

This rectification circuit will be in the power supply board. It is most easily seen in adapters, such as laptop chargers, cell phone chargers… or cellular power supplies that output 12V and 24V DC. To better understand the rectification process, you can refer to the video above.