Problem 7 (25 points): An observer is looking at the reflection of the sky from the surface of a pond through a perfect polarizer. At what angle of observation (line of sight) with respect to the vertical does the reflected light through the polarizer completely vanish? The refractive index of water is 1.33. The observer can rotate the polarizer axis as needed. Problem 8 (15 points): Two long slits 0.1 mm wide, separated 0.7 mm in an opaque screen, are illuminated by light with a wavelength of 527 nm. The plane of observation is 6 m away. How many Young's fringes are visible within the central bright band?