일반물리학 2 — Magnetic Fields Due to Currents: Problem 58

58 In Fig. 29-62, current $i = 56.2 \text{ mA}$ is set up in a loop having two radial lengths and two semicircles of radii $a = 5.72 \text{ cm}$ and $b = 8.57 \text{ cm}$ with a common center $P$. What are the (a) magnitude and (b) direction (into or out of the page) of the magnetic field at $P$ and the (c) magnitude and (d) direction of the loop’s magnetic dipole moment?