Relative difference between the two-zone model described in Sect. 3.4 with the full model considering a realistic stellar density profile as outlined in Sect. 4.1. The model assumes a white dwarf mass of 0.5M_⊙ and an age of the secondary of 5 Gyr. We employ λ = 0.0096 and ξ = 4/3 as parameters in the two-zone model. The relative deviation of the results is shown as a function of the Applegate parameter A and for different secondary masses. A good approximation requires A ≲ 0.5.