50. What is the interference that produces a bright band in the pattern on a screen? 46. A thin film of oil with a thickness of 90 nm rests on top of a pool of water. When white light incident on the film is reflected, what colors are seen? The refractive index of the oil is noil = 1.45. 46. 47. The brightest spectra produced by diffraction gratings are produced by_ a grating spectroscope c. reflection gratings holographic gratings d. transmission gratings 48. The strongest colors reflected in a thin film have wavelengths in the film equal to of the thinnest possible film. the thickness twice the thickness four times the thickness two or four times the thickness, depending upon the number of wave inversions 49. What is light made of only one wavelength called