Let us consider a conductor AC carrying a current i. The product of the current and a small elementary length dl of the conductor, idl is called a ‘current-element‘.
Statement: The magnetic field at a point due to a small current element idl is –
i. Directly proportional to the current (i).
ii. Directly proportional to the length of the element (dl)
iii. Inversely proportional to the square of the distance (r) of the point from the element.
iv. Directly proportional to the ‘sine’ of the angle (θ) between the current element and the position vector of the point with respect to the element.