Sorry if this is the wrong place to post this, but I wasn't sure where exactly to put it. When we calculate the force on a closed loop of current-carrying wire in a uniform magnetic field, We calculate the line integral of the loop to be 0. However, when we evaluate the line integral for an Amperian loop while using Ampere's law, we integrate from 0 to 2π. Why is there a difference? I'm not very advanced with calculus, so some intuition is all I request.