6.16. Consider a spherical capacitor consisting of concentric conducting spheres of radii a and b. If the region between the spheres is vacuum, then the capacitance is 4лeдab/(b-a). (a) What is the capacitance if the volume between the conductors is partly filled with dielectric as shown in Fig. 6.14(a)? (Hint: Dr is continuous at the dielectric boundary.) [Answer: C = 4лкеoаb(a + b)/((ka + b)(b-a))] (b) What is the capacitance if the volume between the conductors is half-filled with dielectric as shown in Fig. 6.14(b)? (Hint: Et is continuous at the dielectric boundary.) [Answer: C = 2л0(к + 1)ab/(b-a)] Exercises b K --------- K h 219 (a) (b) FIGURE 6.14 Exercise 16. The concentric conducting spherical shells have radii a and b. A dielectric material occupies part of the volume between the spheres. In (a) the dielec- tric is a spherical shell with inner radius a and outer radius (a + b)/2. In (b) the dielectric is a hemispherical shell of thickness b-a.