試題詳解

43. Charge of uniform density (20 nC/m²) is distributed over a cylindrical surface (radius = 1.0 cm), and a second coaxial surface (radius = 3.0 cm) carries a uniform charge density of -12 nC/m². Determine the magnitude of the electric field at a point 4.0 cm from the symmetry axis of the two surfaces (ε0 = 8.85✖10^-12 F/m)
(A) 0.23 KN/C
(B) 1.1 KN/C
(C) 1.7 kN/C
(D) 0.45 KN/C
(E) 0.1 KN/C