In terms of total current, (which is the sum of both free current and bound current) the line integral of the magnetic B -field (in teslas, T) around closed curve C is proportional to the total current I enc passing through a surface S (enclosed by C). In terms of free current, the line integral of the magnetic H -field (in amperes per metre, A·m) around closed curve C equals the free current I f,enc through a surface S.