Let the internal dimensions of a coaxial capacitor be a = 1.2 cm, b = 4 cm, and l = 40 cm. The homogeneous material inside the capacitor has the parameters ε = 10⁻¹¹ F/m, μ = 10⁻⁵ H/m, and σ = 10⁻⁵ S/m. If the electric field intensity is E = (10⁶/ρ) cos 10⁵ta_ρ V/m, find

(a) J;

(b) The total conduction current I_c through the capacitor;

(c) The total displacement current I_d through the capacitor;

(d) The ratio of the amplitude of Id to that of I_c, the quality factor of the capacitor.