(B). A Si sample of 4m thickness is illuminated with with light at a wavelength of 800nm and an optical power of 1mW. What is the absorption coefficient of Si in this case? How many EHP(electron-hole pairs) are created in this sample per second (assuming 100\% quantum efficiency and 30% of the incident light is reflected)? (C). Assume the length of the Si sample in part (B) is 500m, the width is 250m and the thickness is still 4m. Assuming that the generated EHPs in (B) are evenly distributed in the sample, calculate the optical generation rate, gop defined as the number of generated EHP in the sample per second per unit volume