Chapter 13, Problem 13.3P

Drive expressions for the view factor $F_{12}$ associated with the following arrangements. Express your results in terms of $A_1$ , $A_2$ and any appropriate hypothetical surface area, as well as the view factor for coaxial parallel disks (Table 13.2, Figure 13.5).

(a) A circular disk and a coaxial, ring−shaped disk.
(b) A circular disk and a coaxial, right−circular cone. Sketch the variation of $F_{12}$ with ( for $0\le \theta \le \pi /2$ and explain the key features.