Ampere's Law

Description:

Similar to the Gauss’ law of electrostatics, Ampere’s law is useful in finding magnetic field in cases of symmetry. According to this law, the line integral of magnetic field over a closed path (∮ Bdl→ is equal to μ₀ times the net current crossing the area enclosed by that path.

Mathematically,

∮ Bdl→ = μ₀i_net

Positive direction of current and the direction of the line integral are given by the right hand thumb rule.

In order to find magnetic field using Ampere’s law the closed path of the line integral is generally chosen such that B→ is either parallel or perpendicular to the path line. Also, whenever it is parallel to the path, its value should be constant.