Ampere s Law and its Applications #8211; Ampere s law states that the line integral of the magnetic field B around any closed loop is equal to μ<sub>0</sub> times the total current crossing the area bounded by the closed curve provided that the electric field inside the loop remains constant. i.e. ∮Bd I = μ<sub>0</sub> Σ I = μ<sub>0</sub>(I<sub>1</sub> + I<sub>3</sub> #8211; I<sub>2</sub>) = μ<sub>0</sub> I<sub>enc</sub>