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.
◦ 0.45 kN/C
◦ 1.0 kN/C
◦ 0.73 kN/C
◦ 0.56 kN/C
◦ 2.3 kN/C