Chapter 2, Problem 2.75P

Suppose a coaxial capacitor with inner radius 1.0 cm, outer radius 2.0 cm, and length 1.0 m is constructed with two different dielectrics. When oriented along the z–axis, ${\epsilon }_r$ for $0°\le \varphi \le 180°$ is 9.0, and ${\epsilon }_r$ for $180°\le \varphi \le 360°$ is 4.0. (a) Calculate the capacitance. (b) If 9.0 V is applied across the conductors, determine the electrostatic potential energy stored in each dielectric for this capacitor.