Q.A wire loop of the form shown in the figure carries a current I. Obtain the magnitude and direction of the magnetic field at P. (Given a formula for the contribution of one segment, 'segment II', of the loop, in terms of $\mu_0$, I and R.) [The printed answer for this item is a compound expression combining two different radii/segment contributions -- the exact shape of the loop (how many straight and curved segments, their radii, and P's position relative to them) is shown only in the source figure and is not recoverable from the extracted text.]