Final answer:
At Brewster's angle, the fraction of incident power reflected by plexiglass with an index of 3.45 is 0%, and all incident power is transmitted, resulting in transmitted light that is only slightly polarized vertically. The reflected wave is completely polarized parallel to the surface.
Step-by-step explanation:
The question relates to the concepts of reflection, refraction, Brewster's angle, polarization of light, and power transmission in the context of physics. When a right-hand circular plane wave is incident at the Brewster angle into a lossless plexiglass with refractive index n = 3.45, the reflected wave is completely polarized parallel to the incident surface. Due to the nature of Brewster's angle, no power is reflected in the perpendicular component of the electric field, so the fraction of power reflected is 0% for the component polarized parallel to the incident surface. However, in a practical setting, due to imperfections and other modes of polarization, there might be a small amount of power reflection. For the transmitted wave, the fraction of the incident power that is transmitted is essentially all the incident power, since no power is reflected at Brewster's angle.
The polarization of the transmitted wave will not be completely vertical but will have a significant amount of horizontal polarization. The reason is that not all incident light is reflected; hence, horizontally polarized light also gets refracted into the medium. This makes the transmitted light only slightly polarized in the vertical direction.