Answer:
The magnitude of the electric field is 8.47 N/C
Step-by-step explanation:
Given;
uniform charge density, λ = 100 nC/m³
inner radii of the cylinder, r = 1.0 mm and 3.0 mm
distance from the symmetry axis, R = 2.0 mm

Area = 2πrl
Area =2π(2 x 10⁻)l
Volume = A x d
d = Volume / Area

the magnitude of the electric field

Therefore, the magnitude of the electric field is 8.47 N/C