In a charge-free region for which = 0, = o r , and

In a charge-free region for which σ = 0, ε = ε_oε_r, and μ = μ_o,

H = 5cos (10¹¹t – 4y)a_z A/m

find: 

(a) J_d and D, 

(b) ε_r.