Discoveries of Ampere
On the life path of this unusually gifted man, who in his childhood amazed with his outstanding abilities and truly encyclopedic knowledge and an enviable sense of scientific foresight, one can say a lot. Andre Marie Amper introduced the term “electric current” into science and for a century and a half predicted the emergence of cybernetics – the science of the general laws governing control and communication in organized systems.
The starry hour in the life of Ampere came in September 1820 when he first learned about the discovery by the Danish physicist G. H. Oersted (1819) of the action of electric current on the magnetic needle and engaged in the repetition of his experiments. Ampere intuitively understood the significance of this discovery for future successes in the field of electromagnetism. He immersed himself in the study of a new previously unknown phenomenon. First of all, he carefully repeated the experiments of Oersted and immediately noted the inaccuracy
Ampere was the first in the world to utter the words “current strength”. It is not surprising that after many years the “ampere” was named the unit of precisely the current. In 1821, Ampere proposed an “astatic pair” consisting of two magnetic arrows fixed on a common copper axis parallel to each other with poles facing in opposite directions. This became the prototype of a device for detecting current – a galvanometer, and the term “galvanometer” Amper first uses in his works.
Ampere strikingly demonstrated the magnetic properties of wire bent into a ring, similar to the “thin sheet” of
Ampere states that “any small closed current acts on any magnetic pole, just as a small magnet placed on the current site having the same magnetic axis will act.” Ampher repeatedly emphasizes that “the only cause of electromagnetic phenomena is electricity.” Ampere put forward a fundamentally new, radical and even seemingly bold idea: there are no magnetic charges in nature at all, there are only electric charges, and magnetism only arises from the motion of electric charges, that is, because of electric currents.
He suggested that the direction of the positive direction of electricity from positive to negative in the external chain be taken as the direction of the current. He managed to formulate a rule about the direction of the deviation of the magnetic needle, depending on the direction of the current in the conductor. This rule became known as the “swimmer’s rules” and was formulated as follows: “If one mentally places a person along a conductor with a current so that the current passes in the direction from the observer’s feet to the head, and that his face is turned towards the magnetic needle, then under the influence the north pole of the magnetic needle will always deviate to the left. “
On the basis of numerous experiments, Ampere formulated the law of direct current interaction: “two parallel and identically directed currents are attracted, while two parallel and oppositely directed currents are repelled.” In order to find out how the currents interact in different contours, he had to formulate the laws of the magnetic interaction of the individual current elements (“Ampere’s law”) and the effects of currents on magnets (the “Ampere rule”).
He invented and manufactured a number of devices with which he, having extensive mathematical knowledge, was able to perform fairly accurate measurements of the strength of the magnetic interaction of currents. Later, the great Maxwell noted these dimensions as extremely original. Not everyone knows that Amper was one of the pioneers of electrometry. In the German Museum of Masterpieces of Science and Technology, Ampere’s original instruments are stored, with the help of which he produced experiments. In the illustrated guide to the museum it is said that “Ampere instruments belong to the number of the most precious exhibits of the museum.” The nondescript, wax-coated composite wire contours hanging and rotating in cups with mercury connected to the current switch are placed in a cabinet decorated with rich carvings and portraits.
In fact, Ampere created a new science of electricity and magnetism, and even the term “Electrodynamics”, which later became the name of one of the greatest sections of classical physics, was introduced by Andre Marie Ampere himself.
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