.50. || Use the graph in Figure 23.29 for silicate flint glass. (a) What are the indices of refraction of this glass for extreme violet light of wavelength 400 nm and for extreme red light of wavelength 700 nm? (b) What are the wavelengths of 400 nm violet light and 700 nm red light in this glass? (c) Calculate the ratio of the speed of extreme red light to that of extreme violet light in the glass. Which of these travels faster in the glass? (d) If a beam of white light in air strikes a sheet of this glass at 65.0° with the normal in air, what will be the angle of dispersion between the extremes of visible light in the glass? In other words, what will be the angle between extreme red and extreme violet light in the glass? Index of refraction (n) 1.7 1.6 1.5 1.4 400 Slicate flint glass Borate flint glass Quartz Silicate crown glass Fused quartz Fluorite 500 600 700 Wavelength in vacuum (nm) ▲ FIGURE 23.29 Variation of index of refraction with wavelength for several materials.