How did the negative electrode in the rectifier circuit come from?

I find this question difficult to answer. . . After reading it, you don't know where to communicate. . .

First of all, I want to explain some basic knowledge: what is electricity? There are millions of substances that make up the world, but according to modern science, they are all composed of protons, Chinese characters and electrons (no discussion field). In which neutrons have no charge, protons have a unit positive charge and electrons have a unit negative charge. So basically, protons and electrons are the origin of electrical phenomena (antimatter is not discussed). Let's take an electron as an example. When an electron moves in one direction, an electric current is generated. Why do electrons move in one direction? Because charges have an important property: like charges repel and different charges attract. It's like two magnets repel each other on the same horizontal plane and attract each other on different magnetic poles. Therefore, in electrical problems, the movement of charges is due to the attraction of different charges nearby or the repulsion of the same charges nearby. Macroscopically, this is because the potential difference forces the charge to move directionally. Loosely speaking, because the voltage between two points is different, the charge flows from high voltage to low voltage, forming a current. For the power supply, one pole where the current flows out is called the positive pole, and the other pole where the current flows in is called the negative pole, which is artificially specified, artificially specified and artificially specified. Regarding direct current and alternating current, direct current is constant in the current direction (amplitude sum), while alternating current is periodic with time in the current direction (amplitude sum). The direction of common alternating current will change dozens of times a second, which is too fast for human perception, so we generally don't talk about positive and negative poles, but at every moment, the current will flow from one pole and flow in from the other. The outflow electrode was the positive electrode at that time, and the inflow electrode was the negative electrode at that time, but they were constantly changing with time. For direct current in the same direction, the pole where the current has been flowing is naturally called the negative pole. The rules of this name are artificial. On the other hand, in the conventional steady-state (that is, long-term) electrical problems, the current will inevitably come out and go in. To form a circular path, the charge is unstoppable. Just like you put the battery next to the light bulb, the light bulb won't light itself. You need to connect them with wires to form a circulating path to generate current (insulation breakdown is not discussed). Therefore, as long as the power drive circuit is connected, there must be both positive and negative electrodes.

Let's talk about the picture of 6A you gave us. You should mean that the left is connected with the right. In the circuit diagram, each electrical component has its own symbol. The wavy line on the left has different meanings from the straight line. A straight line represents a conductor, and a wavy line represents an original object called an inductance (of course, this kind of inductance element is usually wound with a conductor wire, but the role of the conductor in the circuit is different from that of a straight conductor after being wound into such a different shape). Therefore, it should not be understood that the positive and negative electrodes are connected together, and there is a device called inductance between them (this circuit can also be understood as power supply).

Very verbose. You probably know a lot. Let's discuss what you don't understand.