12. Calculate the wavelength of {}^ast (a) the sodium line at 589 nm in an aqueous solution with a refractive index of 1.35 . (b)the output of a ruby laser at 694.3 nm when it is passing through a piece of quartz that has a refractive index of 1.55 .

To calculate the wavelength of light in a medium with a refractive index, we can use the formula: where is the wavelength in the medium, is the wavelength in vacuum, and is the refractive index of the medium.(a) For the sodium line at 589 nm in an aqueous solution with a refractive index of 1.35: (b) For the output of a ruby laser at 694.3 nm when it is passing through a piece of quartz with a refractive index of 1.55: Therefore, the wavelength of the sodium line in an aqueous solution is approximately 435.19 nm, and the wavelength of the ruby laser output in quartz is approximately 448.71 nm.