Find the values of `ointvecB.vec(dl)` for the loops `L_1, L_2 and L_3` in Fig. (The sense of `vec(dl)` is mentioned in the figure)

Explanation

for `L_(1)ointvecB.vec(dl)=mu_(0)(I_(1)-I_(2))`
here `I_(1)` is taken positive because magnetic lines of force produced by `I_(1)` is anti clockwise as seen from top. `I_(2)` produces lines of `vecB` in clockwise sense as seen from top. The sense of `vec(dl)` is anticlockwise as seen from top. for `L_(2):ointvecB.vec(dl)=mu_(0)(I_(1)-I_(2)+I_(4))`

for `L_(3):ointvecB.vec(dl)=0`