Explain : "For some uses Ampere's circuital law `ointvecB*vec(dl)=mu_(0)I` is easy".

Explanation

1. For some uses, a closed loop (which is called Amperian loop) is supposed in which at all points either,
(i) `vecB` is tangential for this loop and B is non zero.
2. Thus, Ampere.s law and Biot-Savart.s law associate magnetic field and electric current. These laws explain the results due to steady currents.