일반물리학 2 — Magnetic Fields Due to Currents: Problem 36

36 In Fig. 29-46, point P is at perpendicular distance \( R = 1.50 \text{ cm} \) from a very long straight wire carrying a current. The magnetic field \( \vec{B} \) set up at point P is due to contributions from all the identical current-length elements \( i \, d\vec{s} \) along the wire. What is the distance \( s \) to the element making (a) the greatest contribution to field \( \vec{B} \) and (b) 10.0% of the greatest contribution?