A cylindrical rod of length $h$ and diameter $d$ is placed inside a cubic enclosure of side length $L. S$ denotes the inner surface of the cube. The view-factor $F_{S-S}$ is
- $0$
- $1$
- $\frac{\left(\pi d h+\pi d^2 / 2\right)}{6 L^2}$
- $1-\frac{\left(\pi d h+\pi d^2 / 2\right)}{6 L^2}$