Electric Field Due to Spherical Distribution of Charge. A spherical region 0 ≤ R ≤ 2 mm contains a uniform volume charge density of 0.5 C/mm3, whereas another region, 4 mm ≤ R ≤ 6 mm, contains a uniform charge density of −1 C/mm3. If the charge density is zero elsewhere, find the electric field intensity E for (assume ε = ε0 ): (a) R ≤ 2 mm. (b) 2 mm ≤ R ≤ 4 mm. (c) 4 mm ≤ R ≤ 6 mm. (d) R ≥ 6 mm.