일반물리학 2 — Gauss' Law: Problem 18

18 A long, nonconducting, solid cylinder of radius 4.0 cm has a nonuniform volume charge density \(\rho\) that is a function of radial distance \(r\) from the cylinder axis: \(\rho = Ar^2\). For \(A = 6.3 \text{ \(\mu\)C/m}^5\), what is the magnitude of the electric field at (a) \(r = 3.0 \text{ cm}\) and (b) \(r = 5.0 \text{ cm}\)?