Electromagnetic torque at the outer boundary as a function of the thin-wall parameters c and ﹩c^{\prime} ﹩. Triangles mark cases where c is fixed to 10⁻⁴ and only ﹩{c}^{{\prime} }﹩ is varied, while circles mark cases where c is equal to ﹩{c}^{{\prime} }﹩ and varied. The results presented here are computed for Ek = 10⁻⁶, although they are identical to computations with a different Ekman number.