일반물리학 2 — Electric Fields: Problem 11

11 In Fig. 22-27, two curved plastic rods, one of charge $+q$ and the other of charge $-q$, form a circle of radius $R = 4.25\text{ cm}$ in an $xy$ plane. The $x$ axis passes through both of the connecting points, and the charge is distributed uniformly on both rods. If $q = 15.0\text{ pC}$, what are the (a) magnitude and (b) direction (relative to the positive direction of the $x$ axis) of the electric field $\vec{E}$ produced at $P$, the center of the circle?