What are the different units of Stefan-Boltzman's constant? What is the dimensional formula for Stefan-Boltzman's constant?

Two infinite parallel plates are placed at a certain distance apart. An infinite radiation shield is inserted between the plates without touching any of them to reduce heat exchange between the plates. Assume that the emissivities of plates and radiation shield are equal. The ratio of the net heat e

A solid cylinder (surface 2) is located at the center of a hollow sphere (surface 1). The diameter of the sphere is 1 m, while the cylinder has a diameter and length of 0.5 m each. The radiation configuration factor F11 is ______ A. 0.375 B. 0.625 C. 0.75 D. 1