Through historical facts, we saw that Oersted was the first to carry out experiments that proved the existence of a relationship between electrical and magnetic phenomena, that is, he showed that electrical currents give rise to fields magnetic. Although he claimed such an existence, Oersted did not explain how to perform the field calculations. This explanation only came later, given by French scientists.
After Oersted's experiment was released in the year 1820, two scientists, Jean-Baptiste Biot (1774-1862) and Félix Savart (1791-1841), made the first reports more precisely about the phenomenon. After undergoing some changes, the conclusions of the two scientists became known as Biot-Savart's Law.
In the figure above we have a positive charge q that moves with a velocity v. Let us now consider the plane determined by v and P: through the right-hand rule we can determine the magnetic field (B), produced by the charge at a point P at a distance r from it. From the figure, we can see that the field is perpendicular to the plane. In this way, we can find the magnitude of the magnetic field (B) through the equation:
where km is the magnetic constant whose value in SI is given by km = 10-7.
In the figure above we have a wire traversed by a current i. To find the value of the magnetic field produced by the current at a point P, we split the wire into small pieces (ΔL). So, the magnetic field (ΔB) produced in each piece is given by the following equation:
By Domitiano Marques
Graduated in Physics
Brazil School Team
Electromagnetism - Physics - Brazil School
Source: Brazil School - https://brasilescola.uol.com.br/fisica/a-lei-biotsavart.htm
