4. Extraction of Light from a High-Refractive-Index Medium. Assume that light is generated isotropically in all directions inside a material of refractive index n = 3.7 cut in the shape of a parallelepiped and placed in air (n = 1) (see Exercise 1.2-6). (a) If a reflective material acting as a perfect mirror is coated on all sides except the front side, determine the percentage of light that may be extracted from the front side. (b) If another transparent material of refractive index n = 1.4 is placed on the front side, would that help extract some of the trapped light