5. (5%, 本題計算過程須計分) Find an equivalent resistor Z = __(5)__ (Fig. 3 lower) for the infinite blocks of resistors (Fig. 3 upper).
5. (5%, 本題計算過程須計分) Find an equivalent resistor Z = __(5)__ (Fig. 3 lower) for the infinite blocks of resistors (Fig. 3 upper).