Cronologia do Eletromagnestismo

 

The Timeline of Electromagnetism

            Electromagnetism is a field in physics that studies electromagnetic fields, a phenomenon created by the physical interaction between electric and magnetic fields. The principal development of it took place in the 19th century.

            In 1820, through an experiment in which a compass needle’s position was disturbed when in proximity with an electric current, Hans Christian Ørsted was able to conclude that electric charges generate magnetic fields, thus establishing a connection between electricity and magnetism. This discovery marked the start of electromagnetism. In turn, in the year of 1831, Michael Faraday discovered electromagnetic induction, which consists of inducing an electric current (in a nearby circuit) with a changing magnetic field. Two years later he introduced lines of force and fields, two concepts essential to the furthering of knowledge in physics. Faraday’s work was later simplified in one of James Clerk Maxwell’s papers, which also expanded on the connection between magnetism and electricity through the formulation of 20 equations. Maxwell published an article in 1865 in which he stated light was an electromagnetic phenomenon, since, according to calculations, the speed of an electromagnetic field’s propagation is the same as light’s. This would make light an electromagnetic disturbance which travels through a field. The 20 differential equations previously mentioned were simplified by mathematician Oliver Heaviside and reduced to only four, known as the Maxwell equations. Over a decade after Maxwell had proposed the existence of electromagnetic waves, Heinrich Hertz was able to prove that the theory was in fact true. By conducting a series of experiments (from 1886 to 1888) where electromagnetic waves were produced and their characteristics were compared to light, Hertz came to the conclusion that both the waves and light are forms of electromagnetic radiation that abide by Maxwell’s equations, though the former possess a longer wave length. Hertz’ work largely contributed to the development of technologies such as radios, radars and televisions. Finally, in 1888, Nikola Tesla was heavily involved in the creation of an electric motor powered by an alternating current. The electric current was obtained by electromagnetic induction. Another invention, the Tesla coil (1891), an electrical resonant transformer circuit that produces a high-voltage, low-current and high frequency alternating current, is utilized for educational purposes.

            Without these pioneers in the field of electromagnetism, society certainly wouldn’t have evolved the same way, given that these discoveries paved the way for the creation of modern communication methods, like the radio or television. These mathematicians and physicists made it so we understood one more aspect of the reality we live in, a reality with so many unknowns.

Informação sobre físicos importantes no ramo do eletromagnetismo

Trabalho realizado por :

André Dias n°3  11°A
Frederico Ferreira n°5  11°A
Inês Miguel n°9  11°A
Sara Reis n° 20  11°A

Beatriz Dias n° 22  11°A