$7\mathrm{.}37*$ For light at a wavelength of l$1=656\mathrm{.}3$ nm water $($at $20\backslash$deg C$)$ has$($b$)$ Why does the series contain harmonic terms having arguments an index of n$1=1\mathrm{.}3311.$ At a wavelength of l$2=589\mathrm{.}3$ nm water haswith odd and even multiples of vt$?($c$)$ What is the value of the DC an index of n$2=1\mathrm{.}3330.$ Determine the approximate value of theterm? $($d$)$ What is the value of A$0?($e$)$ What is the value of the period group velocity of light in water.