Walker, Halliday & Resnick — Magnetic Fields Due to Currents: Problem 47

47 In Fig. 29-52, a current \(i = 2.2 \text{ A}\) is set up in a long hairpin conductor formed by bending a wire into a semicircle of radius \(R = 8.5 \text{ mm}\). Point \(b\) is midway between the straight sections and so distant from the semicircle that each straight section can be approximated as being an infinite wire. What are the (a) magnitude and (b) direction (into or out of the page) of \(\vec{B}\) at \(a\) and the (c) magnitude and (d) direction of \(\vec{B}\) at \(b\)?