Alternating current refers to an electric current whose magnitude and direction change with time, while direct current does not change with time and is constant. There are many differences between the two in use, and each has its own advantages. Everyone should have heard about the feud between Nikola Tesla and Edison. The two once caused a "current war" because of alternating current and direct current.
What is the difference between alternating current and direct current
In the 19th century, Edison invented direct current and was a promoter of direct current. At that time, almost everyone believed in direct current, believing that the direction of the current of direct current remained unchanged, while alternating current repeatedly changed the direction and magnitude of the current from beginning to end, and it was impossible to use alternating current in practice. At that time, Edison was vigorously promoting and researching direct current equipment, but Edison encountered many difficult problems when inventing the light bulb. He found that when using direct current, the light bulb could not get enough current and could not emit light when the distance was far.
Later, Nikola Tesla appeared. He was a promoter of alternating current and tried to persuade Edison. He suggested-alternating current transmission. AC motors are simpler in structure and easier to transform than DC motors. They can solve the problem of increasing the transmission voltage in a simple, economical and reliable way. However, Edison was indifferent to Tesla's suggestion that AC had many advantages, and his AC suggestion was strongly rejected by Edison!
Later, Tesla went to work at Westinghouse, designed many AC devices, and maturely introduced them to the market. Later, he was strongly suppressed by Edison and slandered AC. In order to obstruct the development of AC, Edison not only conducted AC electrocuted animals in public and mobilized the media to report AC accidents, but also promoted the invention of the electric chair - using AC to execute the death penalty. The "current war" between them began from then on. Later, in this AC-DC battle, AC, which has the advantage of long-distance transmission, still won.
From their "current war", it can be seen that AC and DC each have their own advantages and disadvantages. DC is not suitable for long-distance transmission, while AC can be transmitted over long distances. As mentioned above, if the DC transmission distance is too long, the bulb will not get enough current and cannot emit strong light, so DC has higher transmission loss than AC over long distances. However, the cost of long-distance transmission lines of direct current is lower than that of alternating current, and its voltage is stable, which is also its advantage. In addition, electronic equipment using direct current is not easy to heat up.
What is alternating current? The difference between alternating current and direct current
First, let's understand the difference between the two. Direct current refers to the direction and size are stable and do not change with time, while the other refers to the fact that these two aspects will change with time. Our usual power supply system will change periodically. And they all have their own advantages and disadvantages. Because of these, they are suitable for different places.
Direct current, its direction will not change with time, so it is relatively stable. Now a functional feature that must be in electronic equipment is that it must have good stability. Here we have to use this kind, so we need to use something else, and there will be a certain transformation between the two. And the magnetic field it generates is relatively stable, so it is often used in some important control systems, such as substations, mobile communication base stations, etc.
The voltage of AC power can be changed by transformers, but the other type cannot be achieved at one point. Therefore, in long-distance power transmission, we use the type that can change. This is mainly because the cables are very long. As we have learned physics, we know that this will make its resistance very large and cause a lot of energy loss. Therefore, we must increase the output voltage to reduce losses. Finally, at the terminal, the high voltage can be converted into a more appropriate voltage through a transformer. This is why we use high-voltage AC transmission mode on a large scale and over long distances.
