Ampère's circuital law for a closed loop bounding a surface carrying total current I is correctly stated as:

1. Ampère's law relates the line integral of B around a closed loop to the enclosed current. 2. The integral $\oint \mathbf{B}\cdot d\mathbf{l}$ is taken over the boundary of the surface. 3. The law states this equals $\mu_0$ times the total current through the surface. 4. Hence $\oint \mathbf{B}\cdot d\mathbf{l} = \mu_0 I$. _Source: syllabus Physics Ch 4 "Moving Charges and Magnetism", p.149_