Electric connections

Electric power

Electric power

In general, we define electrical energy or electricity as the form of energy that results from the existence of a potential difference between two points. When these two points are put in contact by an electric conductor, we obtain an electric current.

In physics, the electric potential energy, also called electrostatic potential energy, is the potential energy of the electrostatic field. This is an energy that has an electric charge distribution, and is linked to the force exerted by the field generated by the distribution itself. Together with the magnetic energy, the electric potential energy constitutes the energy of the electromagnetic field.

The electrostatic potential energy can be defined as the work done to create a charge distribution from an initial configuration in which each component of the distribution does not interact with the others. For example, for a discrete system of charges, it coincides with the work done to take individual charges from a position where they have zero electrical potential to their final disposal. The electrostatic potential energy can also be defined from the electrostatic field generated by the distribution itself, and in this case its expression is independent of the source of the field.

This is an amount that can be negative or positive, depending on whether the work done to take it to the assumed configuration is positive or negative. Two interactive charges of the same sign have positive energy, since the work done to bring them closer must overcome their repulsion, while, for the same reason, two charges of the opposite sign have negative energy.

Physical aspects of electrical energy

From the physical point of view, electrical energy is negative electrical charges (electrons) that move through the electrical conductor, usually metallic, due to the potential difference between its ends. The reason why conductors of metallic origin are usually used is because they have more free electrons.

The electric charges that travel through the conductor are part of the atoms of the conductor's own substances.

In physics the potential of electrical energy is also called electrostatic potential energy.

At a slightly more technical level of physics, the potential for electrical energy is the potential energy of the electrostatic field. It is the energy that has an electric charge distribution that is linked to the force exerted by the generated field of the same distribution. Together with the magnetic energy, the electric energy potential is the electromagnetic field energy.

The electrostatic potential energy can be defined as the work done to create a charge distribution from an initial configuration in which each component of the distribution does not interact with the other. The electrostatic potential energy can also be defined from the electrostatic field generated from the same distribution, and in this case its expression is independent of the source of the field.

It is a magintud that can be negative or positive, depending on whether the work done so that they are in the adopted configuration is positive or negative. Two charges that interact in the same sign have positive energy, since the work done to bring them closer must overcome their repulsion. For the same reason, two opposite charges have negative energy.

Electric power generation

Electric power can hardly be found freely in nature in a way that can be used. It can be observed in thunderstorms but the difficulty of storing and controlling such amount of energy makes them practically unusable.

There are several ways to generate electricity that we can classify as renewable or non-renewable. The ways of generating renewable electricity are those in which no fuel is used or the fuel is inexhaustible (solar energy, wind energy, hydroelectric power, geothermal energy, etc.). On the other hand, the ways of generating non-renewable electricity require a fuel that, however abundant, tends to run out such as nuclear energy, thermal energy (coal, oil, gas ...), etc.

Use of electric power

Trains running by electric powerElectric energy can be transformed into many other types of energy such as mechanical energy (electric motors, machines ...), thermal energy (heaters, stoves ...) or light energy (light). The great advantage that electric power gives us is the ease of transporting it.

The use of electricity is widespread in modern society and the current through the connection to the electricity grid or through batteries or accumulators: just think about the use of lighting in buildings (public and private) and roads, in the power of appliances and equipment, as well as in industrial production processes or in electric machines, such as electric motors.

Therefore, the discovery of electric power has represented a very strong real technological, economic and social revolution. Its use has caused a strong and irreversible need due to its benefits compared to mechanical energy produced by thermal engines (combustion engines). Among them was the fact of being able to be transported at a distance, the low operating noise of electrical equipment, the absence of exhaust gases at the place of use and the smallest footprint of an electrical machine.

Among the disadvantages only the fact of not being a primary source. The use of electric power implies the need for a conversion infrastructure that inevitably introduces a loss of efficiency in the conversion process and upstream in transportation along the power lines.

Electric power plants

Electricity, with the exception of lightning atmospheric electricity and the Earth's weakly negative potential, is not a primary energy source of the earth, so it has to be produced by transforming a primary energy source. In this way, electrical energy is considered as a secondary energy source. In the transformation process, the yield always less than 100% is produced within the power plants.

In all the plants of production of electrical energy, with the exception of those of photovoltaic solar energy, three elements are needed to produce electricity:

Towers for the transport of electrical energyAnother important element to produce electricity is water in liquid form (as in hydroelectric power plants) or in the form of high pressure steam (in thermal power plants, geothermal power plants, in nuclear fission and in solar thermal power plants), in order to turn the turbines to produce in a more constant way possible  alternating current  by means of the alternator.

The use of water presents the following problems derived from the need to heat it:

  • Water availability.
  • Thermal water pollution, if not recovered, is dispersed in the atmosphere in the form of water vapor or fed back into lakes, rivers and sea.

In the case of wind plants no water is needed, since the turbines are driven by the force of the wind.

Transportation and distribution of electrical energy

Once the production of electricity is finished, there is a need to transport it on a large scale. The large-scale transport and distribution of electricity produced by the plants to the end users is carried out through the transmission network and the distribution network.

Joule's Law

Joule's law, in reality, is two different laws, which associate the heat generated by the electric current and the dependence of the internal energy of an ideal gas with respect to its pressure, volume and temperature.

Joule's first law (also known as the Joule effect) is a physical law that establishes the relationship between the electric current that passes through a conductor and the heat it generates. The name is dedicated to James Prescott Joule, who worked on this concept in the 1840s and expresses it as follows:

Q = I 2 · R · t

In formula Q it is the heat generated by the constant current I, which passes over a conductor t with resistance R over time. When the current (measured in amps), the resistance (measured in ohms) and the time (measured in seconds), the unit of Q will be joules.

Joule's first law is also sometimes known as the Joule-Lenz law, because he was later found independent by Heinrich Lenz.

Joule's second law means that the internal energy of an ideal gas depends solely on its temperature, regardless of its volume and pressure.

 

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Last review: November 25, 2016

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