What is Biot Savart Law？

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.