The circulation of the vector of the magnetic intensity H along closed contour
Γ1 with length l, which interweaves contour Γ2 with flowing current i through it, is
defined by the formula:
(32) $ H ∙ dl = i
Γ1
It can be seen that the magnetic field is non-potential field since the lines of the
field intensity H are closed and always interweave the contour with the excitatory
current i . The circulation of the vector H will be zero only along those closed
contours that do not interweave the current i .
Fig. 6 The circulation of the vector of magnetic intensity H along the closed
contour Γ1 equals the current i flowing through the interweaved contour Γ2.
25