PX157 - C4a - ampere's law

the law

the line integral of the magnetic field on a closed loop is equal to the $μ_{0}$ times the total current enclosed by the loop:

\oint_{c} \vec{B} \cdot d \vec{l} = μ_{0} I_{e n c l .}

$I$ is positive if the right hand rule is applied to the direction of the line integral