Electric current. It's simple

The question of what is the power of an electric current is not the simplest. To be absolutely precise, it is very difficult. But this is one of the basic concepts of both physics and other scientific disciplines related to electricity. In everyday life, we also often have to use this concept.

Without going into a detailed explanation of what an electric current is and what its nature is, we will use the analogy with a stream to understand the processes associated with it. The water flows from the higher lying down section. For an electric current, the situation is approximately the same, it flows from a point with a high potential to a point with a low potential. The magnitude of the potential difference is called the voltage, denoted by the letter U and is measured in units called volts.

Let's go back to the stream. When water flows from a height to the lowland, a certain amount of water is transferred from one place to another. When the current flows, the same thing happens: a certain amount of electricity is transferred from one place to another. To measure this process, there is the term current strength , it is defined as the amount of electricity that has passed per unit time through the conductor section. By analogy with the stream, this means how much water has passed through the selected area per unit of time. The current intensity is denoted by the symbol I, for its measurement there is a special unit - ampere.

These two concepts - electrical voltage and current - act as the main characteristics of an electric current.

Water, flowing from the top down, carries with it a certain energy. If, for example, falling on the turbine blades, it will cause the rotation of the turbine and perform certain work. Similarly, an electric current can do work. This work, performed in one second, is the power of the electric current. It is accepted to be designated by the letter P, and it is measured in watts.

The work done by the water in the fall is determined by its amount falling on the turbine blades, and the height with which it falls. The more water and the higher the altitude with which it falls, the greater the work is done. Similarly, the greater the voltage (the difference in height for water) and the current (ie, the amount of water), the greater the work done and, hence, the power of the electric current.

If we try to formalize this concept, then everything can be expressed by a simple formula:

P = I * U,

Where: P - electric current, in watts;

I - current strength, in amperes;

U is the voltage, in volts.

This is the basic formula by which it is possible to determine the power of an electric current.

However, the electric current does not flow somewhere in abstract conditions, but in real circuits, which have their characteristics. In particular, the conductor has a resistance, and the voltage U and the current I are connected to each other in a circuit where a constant current flows through the Ohm's resistance. So, the power in the dc circuit can be expressed, if necessary, through the resistance, or take into account the characteristics of the circuit in the expression for the power through the current and voltage connected by Ohm's law.

Due to the fact that the circuit has resistance, not all energy is used to perform useful work. Part of it is lost when passing through the chain. Therefore, the incoming energy, i.e. The power of the energy source must be greater than the power required to perform a certain job. The so-called energy balance must be performed - the power given by the source should be equal to the power of the load consumed and the power lost in the conductor of the electric current.

Approximately so you can get a general idea of what is the power of an electric current, how it is determined, on which it depends.