In physics, electricity is a generic term that encompasses a whole set of phenomena that are the manifestation of the presence of a movement of electric charges. We can apply the term electricity to phenomena known as lightning or static electricity but also to other such as the electromagnetic field or electromagnetic induction. The word also serves to designate the branch of physics that studies electrical phenomena and their applications.
In the following sections we will study electricity from a physical point of view in order to better understand how an electric motor works. The appearance of the electric motor was an important alternative to the thermal engine. Electricity was the trigger for the second industrial revolution.
However, it has not been well into this century that the electric motor has started to have a relevant importance in the automobile industry with the appearance of hybrid and electric cars.
Terms related to electricity
In the general language we can use the term electricity to designate a certain number of phenomena, but it is too ambiguous to be used in different scientific fields and is replaced by a series of more precise concepts:
- Electric current: Movement or flow of electrically charged particles.
- Electric charge: Property of some subatomic particles that determines their electromagnetic interactions. Electrically charged matter is affected by electromagnetic fields and produces.
- Electric field: Effect produced by an electric charge on others that are close.
- Electrical potential: The ability of an electric field to produce a job
- Electromagnetism: fundamental interaction between electromagnetic fields and electric charges and their movement. Electricity is closely related to magnetism and therefore is included within the field of electromagnetism, which studies together electrical and magnetic phenomena.
The electric charge is one of those entities that can be measured and used, but it can not be defined in easily understandable terms, since, like space, time and mass, it is not easy to give an exhaustive definition. Perhaps the best way to define it is to observe its effects. An object equipped with an electric charge exerts a force at a distance on another object that has an electric charge. Unlike gravity, which causes one object to attract another, objects with an electric charge can attract and repel each other. In addition, gravity is directly related to the mass of the objects in question, while the electric charge and the mass are not related when the objects are immobile.
Experiments show that there are two different types of electric charge. The first of these is called positive charge, and is associated with the nuclei of atoms of all chemical species. The second is the negative charge, and is typical of all the electrons that surround the nucleus of the atom. In general, the positive charge of the nucleus is exactly equal to the sum of the negative charges of the electrons that surround it.
The direction of the forces, which act between objects that have an electric charge, depends on the type of charge on these objects. For example, if two objects have the same type of charge, both are positive or both negative, the objects repel each other. When the two objects have opposite charge, they attract each other. This electric attraction force, between the positive nuclei and the negative electrons, joins the latter to the nucleus.
The total amount of electric charges remains virtually constant in the world. Since the two types of charge have opposite effects, the general normal result is electrical neutrality or the apparent lack of charge. Therefore, to observe the effects of loading on fairly large quantities of matter, it will be necessary to alter the normal equilibrium and produce an excess load on the object in the desired manner.
History of electricity
Electricity was studied since antiquity, but it did not begin to be understood until the seventeenth and eighteenth centuries. It was at the end of the 19th century when electrical engineering achieved the use of electricity in industrial and residential applications.
Nikola Tesla and Thomas Edison had a leading role in the expansion and development of the use of electricity, their work allowed the advent of the second industrial revolution. Nowadays, electric power is omnipresent in the everyday life of developed countries: from different sources of energy (hydraulic energy, thermal energy, nuclear energy), the electricity produced is used in homes and industry.