일반물리학 2 — Magnetic Fields Due to Currents: Problem 1

1 In Fig. 29-24, point $P_1$ is at distance $R = 24.0\text{ cm}$ on the perpendicular bisector of a straight wire of length $L = 18.0\text{ cm}$ carrying current $i = 58.2\text{ mA}$. (Note that the wire is not long.) What are the (a) magnitude and (b) direction of the magnetic field at $P_1$ due to $i$? (c) If $R$ is increased, what happens to the magnitude of the field?