What is Biot Savart Law？ - Experts Electrical

The Biot-Savart Law is employed to determine the magnetic field intensity dH near a current-carrying conductor. In other words, it describes the relationship between the magnetic field intensity generated by a source current element. This law was formulated in 1820 by Jean-Baptiste Biot and Félix Savart. For a straight wire, the direction of the magnetic field adheres to the right-hand rule. The Biot-Savart Law is also referred to as Laplace’s law or Ampère’s law.

Consider a wire carrying an electric current I and also consider an infinitely small length of a wire dl at a distance x from point A.

The Biot-Savart Law states that the magnetic field intensity dH at a point

A

due to a current

I

flowing through a small current element dl obeys the following relationships:

Directly proportional to the current $I$ .
Directly proportional to the length of the current element ∣dl∣.
Directly proportional to the sine of the angle θ between the direction of the current (represented by dl and the vector joining the current element to point $A$ .
Inversely proportional to the square of the distance $r$ from the current element to point $A$ .

where k is constant and depends on the magnetic properties of the medium.

µ₀ = absolute permeability of air or vacuum and its value is 4 x 10^-7 Wb/A-m
µ_r= relative permeability of the medium.