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Electromagnetism, a paragraph, a chapter, a Physics exam, for those who are passionate about it is a term that has a precise meaning, but for everyone it is a life-changing concept. IS' at the base of many natural phenomena and of many devices that make everyday life more pleasant, so it is interesting to understand what it is.
Electromagnetism: what it is
This branch of physics studies phenomena of an electrical and magnetic nature and, above all, the correlations present between them. And there are some because they exist magnetic fields produced by electric currents and also electric currents produced by the variable magnetic fields.
When we think of a magnet, the classic magnet comes to mind, in truth there are both permanent magnets and electromagnets. In the first case we are faced with a material or an object that generates a magnetic field without the need for any external stimulus. An electromagnet, on the other hand, to generate the magnetic field must receive the stimulus of an electric current.
Electromagnetism and Physics
Those who remember something of high school physics, if they had it as a subject of study, perhaps connect electromagnetism to Maxwell's equations, as Classical Physics suggests, going so far as to describe physical reality up to certain dimensions, to extend the theory as well in quantum scale, we move on toquantum electrodynamics. On the other hand, when we study electromagnetism combined with general relativity, we remain all'Classical electrodynamics.
If you like physics, at the end of the article, I suggest you also read the one dedicated to Planck's constant
There are several experiments that allow us to experience first-hand what electromagnetism is and what effects it has.
Behind this name is the fact that the electrical interactions can produce magnetic forces and viceversa. Said so it may seem obvious and also simple but before anyone noticed the phenomenon, no one imagined this “magic.
It's all thanks to the Dane Hans Christian Ørsted who, while constructing an electrical circuit for an electrodynamics experiment with his students in 1820, noticed that a magnetic needle placed near a section of the circuit, it "reacted" by orienting itself precisely when current flowed. The needle was arranged perpendicular to the section of the circuit to which it was close.
Today it is a "trivial" electromagnetism experiment but imagine the astonishment of the professor and the consequences that have emerged, they begin to investigate what they have noticed and for the first time connecting electricity and magnetic fields.
Another interesting and fun experiment, even for those without a degree in physics or engineering, is what he sees a magnet next to some iron filings. By moving the magnet, the iron powder changes its arrangement and allows us to understand the magnetic field generated by the magnet in question.
Earth also has a magnetic field, the Earth's magnetic field that is generated by a sort of magnetic dipole that we have to imagine in the center of our Planet. Inclined 11 ° 30 ′ respectto the earth's axis, the dipole has an axis and when this axis "comes up" on the surface, then it indicates i geomagnetic poles.
One of the models used for study electromagnetism and the earth's magnetic field is that of the dynamo. Initially we think of a weak non-uniform magnetic field and a core of the Earth of molten material and good conductor in which there may be internal movements.
Precisely these movements induce a current that produces a new magnetic field which in turn induces a new current in the core which for its part causes a new magnetic field and so on. It is a model that is well described with the name of "Self-excited dynamo".
Electromagnetism and health
For years now, there have been studies in progress and in the newspaper headlines, controversies, on the damage of electromagnetism to our health. There is a relationship between electromagnetic radiation state of health, if any negative effects but the positive, biological ones must not be forgotten, since the same radiations are the basis of many therapies.
As an official reference, also for any electromagnetism measurement campaigns a sample in various Italian locations, there is theARPA (Regional Environmental Protection Agency), also responsible for the authorization regarding the installation and modification of Radio-TV-Cellular systems in accordance with the current standards of the electromagnetic field provided
We find a course dedicated to this below branch of physics in some scientific study paths. These are courses in which you study biological effects of electromagnetic fields and dosimetry. Among the various topics covered there are some more inherent to the medical and health sector, others more technical concerning biomedical instrumentation and related problems: reliability, safety, signal-to-noise ratio, interference. From the scientific and also the medical side, the study of biomedical sensors, also based on the piezoelectricity.
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