Maxwell's law of total current: ∮ l HDL = I (total), who can explain the meaning of the integral part on the left side of the equal sign Such as the title

Maxwell's law of total current: ∮ l HDL = I (total), who can explain the meaning of the integral part on the left side of the equal sign Such as the title

This magnetic field is caused by electric current. The magnetic field around a long straight wire is distributed circle by circle. The intensity is inversely proportional to the distance. You will find that no matter which circle, the field intensity * perimeter is proportional to the fixed value of the current. This is the simplest case
But generally speaking, the magnetic field around the conductor is not a circle. The integral path is not necessarily a circle. But the integral around a circle is still proportional to the current. You need to know why you need a little knowledge of curve and surface integral in high number