일반물리학 2 — Electric Fields: Problem 14

14 In Fig. 22-29, a thin glass rod forms a semicircle of radius \( r = 3.00 \text{ cm} \). Charge is uniformly distributed along the rod, with \( +q = 4.50 \text{ pC} \) in the upper half and \( -q = -4.50 \text{ pC} \) in the lower half. What are the (a) magnitude and (b) direction (relative to the positive direction of the \( x \) axis) of the electric field \(\vec{E}\) at \( P \), the center of the semicircle?