A cylindrical cap

Radius of outer cylinder(R) = 1.5cm = 0.015m

Radius of inner cylinder(r) = 1.4cm = 0.014m

Charge on the inner cylinder(q) = 3.5m = 3.5 × 10^-6C

Length of a co-axial cylinder(l) = 15cm = 0.15m

Capacitance of a co-axial cylinder of radii R and r, is given as:

where ϵ₀ = Permittivity of free space = 8.8510^-12N^-1 m^-2 C²

Therefore,

(Trick: Multiply by 2.303 to convert log_e to log₁₀)

∴ C = 1.210^-10F

Potential difference of the inner cylinder,

∴

∴ V = 2.2910⁴V

Therefore, Capacitance = 1.210^-10F

Potential difference = 2.2910⁴V