20. Green light with a wavelength of 5.7 x 10m strikes a grating containing 4455 slits/cm. Determine the angular positions of the second-order bright line. [ A-4, C-4]6. A ray of light from air, having a refractive index of 1.00, is incident on the surface of a block of glass, having a refractive index of 1.50, at an angle of 33.50. Determine the angle of refraction. (Short answer with steps and proper significant digits)[K-1,C-1]