4.60 A coaxial capacitor consists of two concentric, conducting, cylindrical surfaces, one of radius a and another of radius b, as shown in Fig. P4.60. The insulating layer separating the two conducting surfaces is divided equally into two semi- cylindrical sections, one filled with dielectric e₁ and the other filled with dielectric +2. 82 Figure P4.60 Problem 4.60. (a) Develop an expression for C in terms of the length I and the given quantities. *(b) Evaluate the value of C for a 2 mm, b = 6mm, ₁ = 2, n Er₂ =4, and 14 cm.