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Electromagnetism definition
Electromagnetism encompasses all phenomenon caused by presence of electric charges in motion and at rest. The first attempts to educate people about electricity can be traced in the early 6th century B.C. at the point that Thales of Miletus discovered the magnetism of straw pieces applying amber rubbing. Research into magnetism started when it was discovered that there were a few “stones” attract iron. Electricity and magnetism were distinct from one the other until around 1820, when Hans Christian Oersted (1777-1851) discovered the possibility that an electrical current running through a straight conductor, might influence the behavior of a magnetic needle. This discovery sparked the study of e. which was developed due to the efforts of numerous researchers, including Michael Faraday. The basic laws that govern e. were created in the work of James Clark Maxwell (1831-1879). These laws, also known as Maxwell’s equations play a part in electromagnetism like Newton’s equations of motion as well as universal gravity in mechanics. Maxwell demonstrated that light is an electromagnetic phenomenon in nature, and its speed is determined using only magnetic and electrical measurements. Optics therefore was connected to electricity and magnetism. The scope of applications of Maxwell’s equations is vast and encompasses among others, the fundamentals of various gadgets like generators, electric motors particles gasoline pedals, computer radio television, radar microscopes and telescopes. The most significant contributions to the advancement of classical instruction in optics, e. and optics were created by, for example: English physicist Oliver Heaviside (1850-1925) and Dutch physicist H.A. Lorentz (1853-1928). Heinrich Hertz (1857-1894) produced the electromagnetic waves predicted by Maxwell in the lab. The practical application of Maxwell Hertz’s electromagnetic wave was discovered through Marconi as well as other researchers. Maxwell’s equations are in an ongoing and extensive use in science and technology, as well as in various practical problems. In the field of theoretical research, the work is currently being conducted to extend Maxwell’s equations such a manner that. theory is transformed into a distinct instance of a larger theory. This theory will comprise the gravitation theory as well as quantum Physics. As of now there is no general theory that has been developed with any success.
Who discovered electromagnetism
Lightning St. Elmo’s Fires (small electric discharges on different surfaces that occur prior to thunderstorms) as well as other electromagnetism field interactions have intrigued individuals since the beginning of the age of. As time passed, in various regions of the globe, its various manifestations were identified and efforts were attempted to explain the phenomena. Ancient Egyptians have already, in their writings dating back to 2750 BC identified a fish now referred to as the electric catfish. It generates electrical discharges.
In these texts, it is called”the “Thunderer of the Nile,” which suggests that the Egyptians observed the similarities between the atmospheric phenomenon and the abilities of the fish.
Ancient Greeks on contrary, described particular characteristics in magnetite (one of the minerals that has the magnetic property) and amber, which when rub, attracts objects like feathers or dust. They also noted in the amber’s surface that amber that it was rubbed, there could be sparks.
The study of these phenomena was conducted in the works of Aristotle along with Thales of Miletus who were among the most influential thinkers of the day. Roman as well as Arab scholars also were fascinated by electromagnetic phenomena and in a few of their works we can discover references to the paralyzing qualities of the electrical discharges generated by electric rays and catfish. There were attempts to use the rays to treat sufferers from migraines and gout.
As we know that in the realm of technology, China was often far ahead of the rest of the nations in the world this was the case with the actual use to electromagnetic field. From 83 BC and written by an historian in the Chinese Han dynasty, we have mentions of “magic spoons pointing north”.
There was some way to go before the knowledge could be applied in the real world. But it was in China around the 8th century when the first ever compass device was constructed. Based on the response of a needle that is small to the earth’s magnetic field It is the first device made by humans that relies on electromagnetic fields.
Although despite the fact that the invention gained popularity in other countries however, it was utilized for a long time without knowing the way it performed. It was only in around the year 1314 that the French researcher, Petrus Peregrinus, studied the idea as well as wrote the very first book about how magnets behave magnetically that act on the Compass needle.
While the phenomena of electromagnetic field were observed and tried to understand over the years, the actual revolution was not realized until the 16th and 17th century. The possibility of a link with electricity as well as magnetism was first discovered by the Italian scientist Gerolamo Cardano, who outlined his theory in 1550.
But the true leader in this field came to be the physician for the court of the Queen Elizabeth I, The Dr. William Gilbert, who in 1600 , published a book “On Magnets, Magnetic Bodies and the Great Magnet of the Earth”. The book contained the results of his 17 years of study in magnetism and electricity during which there was a number of things that he discovered. Gilbert made one of the primary distinctions between these two phenomena (“the force between magnetic objects tends to align them to one another (…), and the force between electric objects is more of the result of a force in attracting or repelling two objects”).
He also found out that the Earth as an object has the ability to generate its particular magnetism which was his first to develop the notion of an field. It was thought that for an electrical and magnetic exchange to occur physical contact between two objects was required. Gilbert however, on contrary, demonstrated that direct contact isn’t required, and that the reaction could occur at a distance through interactions with an field.
A little over half a century later another significant historical event in the field of the field known as electromagnetic field research occurred which is undoubtedly the most significant in the field of electricity itself. The year 1663 was when German researcher Otto von Guericke invented an electrostatic generator that generated sparks through friction. It is thought to be the first to generate electricity.
The following years saw numerous notable scientists from various nations (including Pieter van Musschenbroek, Benjamin Franklin and Alessandro Volta) developed this device, designed their own devices, and conducted many research related to electricity. They studied different levels of current relays, electrically conductory materials, and the potential for application in the real world. Unfortunately, when faced with such an intriguing object of research, the subject of the magnetism-electricity relationship itself has mostly receded into the background somewhat.
The breakthrough in electromagnetism occurred in 1820, when Danish science researcher Hans Christian Orsted, while prepping to deliver a lecture and observed something unusual that was the reaction of a compass needle with another device nearby, generating electricity. When he analyzed the connection, he realized that electricity might influence magnetism. This is why he was the first person to identify the mechanism behind electromagnetism.
In the wake of Orsted’s astonishing discovery and the ensuing controversy, the French mathematician and physicist Andre Ampere also undertook his own research in this field. This is why Ampere proposed an organization of the field of electrical energy into two fields of electrodynamics and electrostatics which is still relevant to this day. He also outlined mathematically the quantitative relations between magnetic and electrical phenomena, and developed the Ampere’s Law[88 (the law linking the magnetic induction in conductors with the magnitude of the electrical current that flows through the conductor).
In the 1820s as well in the 1820s, based on the findings by von Guericke as well as Orsted, German scientist Johann Schweigger invented the first galvanometer, which was a device that could measure the power of electrical current. Although the machine of Schweigger was highly effective however, it wasn’t discovered how it operated (as as for that of the compass).
The situation was transformed through the work of a renowned scientist, Michael Faraday, who managed to understand the basic principles of magnetic generators as well as electromagnetism itself. In the course of his research – in 1831, it was revealed the fact that both current can create an electromagnetic field and magnetism can trigger the production electric current (Faraday’s Law of Electromagnetic Induction). With their research, Orsted and Faraday accomplished an important feat They were the first to recognize the interplay between electricity and magnetism and also influenced numerous other scientists (including Franz Ernst Newmann, Wilhelm Eduader Weber, William Thomson as well as James Prescott Joule) to study this issue.
It’s safe to say the time is now to one of the major characters in this story. James Clerk Maxwell, because Maxwell is the person who is in question, appears nearly every time it is mentioned that the electromagnetic field is mentioned. In the 1850s Maxwell proved that electricity and magnetism influence each other and interact, but that they are “two kinds of the same phenomenon – electromagnetism” and using the known Maxwell’s equations, established that this phenomena exists. Furthermore, he proved the fact that both electricity and magnetism travel through the vacuum as of waves, and thus , discovered an existence for electromagnetic wave. Thanks to Maxwell’s theories and these equations that it was possible as well as determine the speed at which light travels. However, the scientist did not have the ability to scientifically prove the accuracy of his observations, consequently, they weren’t widely valued throughout his lifetime.
In 1886, another brilliant researcher, Heinrich Hertz, undertook to test Maxwell’s theories in the real world. Through an instrument he designed called Hertz’s oscillator generated electrical waves, for the very first time, and proved the validity of Maxwell’s theories in the real world. Despite his accomplishment, Hertz did not see any potential in his invention. However, other researchers also noticed the potential, such as Oliver Lodge, whose scientific research as well as his invention (coherer) set the stage for the modern wireless communications.
Electrons were discovered. It was an event to be noted. It was a lengthy process that involved several scientists that were guided by the concepts that underlie electromagnetism theory. It was in 1858 that German scientist Julius Plucker placed two electrodes inside the vacuum tube (devoid of air) and then resisted the creation of an electric connection between the two electrodes. The result was that an odd green glow was visible on the tubes’ walls.
While this phenomenon was examined numerous times, it wasn’t until 1879 when Sir William Crookes deduced that the glowing rays were made up of charged particles electrified. In 1898 Sir J.J. Thomson “identified the ray … as a stream of negatively charged particles, each having a mass less than that of a hydrogen ion”. They were the particles that were later referred to as electrons. In the wake from this research, the electromagnetic theory was made an integral component of atomic theory as well as the nature of matter. Because everything is made up of atoms and that they are connected to electromagnetic activity and electromagnetic action, it is safe to say electromagnetic phenomena are widespread.
Naturally, both during the events discussed and afterwards these, numerous other important research studies were conducted that were related in various ways to electromagnetic field. In the present, there is research being conducted in this field including, for instance, researchers from the U.S. Agency DARPA (Defense Advanced Research Projects Agency) that, within the context of its RadioBio project is studying “whether there are targeted electromagnetic signals emitted between biological cells, and if there are, what information is transmitted by these signals.”
How does electromagnetism work
Magnetic field of the coil
If you place your right hand in the cylindrical coil to ensure that your four fingers are in toward the direction that current circulation in the coils and your thumb is deflected, it will be pointed towards magnet field lines that run through the coil.
If the current in the coil increases, it means that it will be magnetic, field in the coil is likely to become stronger. If the current running into the coil is reduced, it’s field of the magnetic field in the coil is likely to weaken. In the event that the coil gets stretched, and its distance grows then the magnetic field that the coil will be less powerful. If the coils are closer to each other, then there is a magnetic field of the coil will be stronger.
Self inductance of the coil
The parameter that determines magnetic properties of the coil (ability to generate the magnetic field) can be measured by the amount of inductance the coil has. The inductance of a coil can be identified by the letter. The unit for inductance is henr. The inductance of a coil which is wound around the core, and is seated for around n turns and whose length is l, can be determined using the formula:
Where:
l – length of the coil [m].
n – number of coils
S – cross-sectional area of the core [m2]
μ – magnetic permeability of the core (the higher the core has better magnetic properties) [H/m].
The actual coils contain an inductance intrinsically under 1H. It is usually described by millihenry (mH) or microhenry (mH).
If a central core is put inside the coil e.g. an iron core (contains iron) The magnetic field is extremely powerful. This is how we can create an electromagnet.
Electrodynamic force
If an electrical current runs through a wire, there is the magnetic field surrounding the wire. If this wire is put within the magnetic field of a magnet the magnetic field will interact with the magnetic field of the wire. In the course of this interaction, a force exerts itself over the wire. This force is referred to as electrodynamic force.
An electrodynamic force refers to the force by which magnetic field is able to influence the wire that has current being inserted into it.
The left hand rule
If we put our left hand within the magnetic field in such a way that magnetic field lines are able to enter our palm, and all four fingers are pointed toward the direction of flow of the current and the thumb that is tilted is pointing toward to the direction of force that is acting over the wire.
The electrodynamic force is determined by the formula:
F=B I l
Where:
B – magnetic induction (in teslas [T]), determines the strength of the magnetic field,
I – current flowing in the wire (in amperes [A]),
l – length of the conductor covered by the magnetic field (in meters [m]).
Electromagnetic force field
The electromagnetic field is generated by the co-existing electromagnetic field along with the magnetic field and is a term used to describe the energy stored in electromagnetic space, be it in physical objects, such as metal objects, or in our bodies, even in the vacuum or air.
The electromagnetic field is the state of energy in the space around electric charges. It is which is characterized by two vector variables which are: The electric field strength and magnetic field strength. Electric field is generated through the interaction of electrically charged objects. A magnetic field can be observed around charges that are moving (i.e. producing the electric current) or on permanent magnets. Static fields, magnetostatic or electrostatic, are formed around stationary charges or those that move in a static fashion (direct current). Electromagnetic radiation is created by interconnected, alternating high-frequency electric and magnetic fields that travel in an atmosphere with the velocity of light.
The intensity of electromagnetic fields that are measured as broadband at workstations, in majority of office spaces are:
– Low-frequency magnetic and electric fields from computer equipment energy supply system, electronic devices, and power supply installation – magnetic field: up to 0.5-1.5 1 uT and electric field strength: from a few to many dozen V/m
– Medium frequency electric and magnetic fields generated by computer equipment magnetic induction is less than 1 uT electric field strength lower than a few V/m
– Radio-wave electric field from transmitters outside of buildings – electric field intensity: below 1 V/m.
References:
http://www.uwm.edu.pl/studydays/files/pole-magnetyczne-i-sila-elektrodynamiczna.pdf
