What is a sinusoidal current

The fact that there is a variable sinusoidal current in the conductors of household wiring is heard by everyone. But for a person unfamiliar with electrical engineering, the terms "sinusoidal" and, especially, "variable", do not say anything. In this paper, we will try to give a general idea of this, accessible to everyone.

First of all, you need to determine what is an electric current. According to the existing explanation, the current is the directed motion of elementary particles, which has a charge of a positive or negative sign. Usually particles are understood as electrons, but this is not entirely true. An atom that has lost an electron, due to the protons present in the nucleus, acquires a positive charge, becoming an ion. EMF acts not only on the electron, but also on it. Suffice it to recall that in calculations for the positive direction of current flow is taken from plus to minus, although in reality, negatively charged particles move in the opposite direction.

Where do these particles come from? Let us imagine the structure of a conductor: a crystal lattice with atoms at the nodes. Each atom can be conditionally described as a miniature solar system. In the center is a massive nucleus consisting of protons and neutrons, and around it orbits rotate electrons.

The proton charge is positive, and the electron is negative, so they are attracted to each other. The closer to the core, the stronger this interaction. To create a current, it is necessary to release a part of the electrons from the atoms and make them move in the right direction. In generators, this problem is successfully carried out by a rotating magnetic field. It communicates the missing energy to electrons in outer orbits, releasing them. Of course, there is no direct movement. We are talking about the exchange of these particles between the nearest atoms.

Where does the name "sinusoidal current" come from? The reason is in the method of obtaining. Let us imagine two opposite poles of a magnet, and between them the lines of field strength. We place the frame from the conductor in this field. Its ends are connected to the load, forming a contour (chain). Rotate the frame. At the moment when it is parallel to the surfaces of the magnet, there is no current, since there is no intersection with the tension lines (both sides of the frame are on the same level). Here it is a little turned, the lines of the magnetic field cross the conductor, release electrons and a current arises.

At the same time, the other side of the frame also crosses the field, but from the opposite side. The maximum current value is for vertical placement. A sinusoidal current is a graphical representation of the process. Without it, it is difficult to understand the operation of electrical appliances. The graph representing the sinusoidal current is the Cartesian coordinates on the plane. The vertical axis is the current, and the horizontal axis - the time. Since with the rotation of the frame the recorded values are periodically repeated, a sinusoidal current varying in direction and magnitude is formed. The sine wave is as if strung on the time axis, since some of the waves are located above the axis (positive sign), and the part below (negative). The highest wave points correspond to the position of the frame parallel to the lines of field strength, and the intersection of the time axis (the current is zero) is perpendicular.

Electric circuits of sinusoidal current have become most widespread, since this type of electricity is very easily converted with the help of transformers and other elements of the electrical circuit, allowing long distance transmission, as well as the required modulation. In addition, the very principle of generation involves the creation of a sinusoidal current.