$35.($II$)$ If the wedge between the glass plates of Example $346$ is filled with some transparent substance other than air$$say$,$ water$$the pattern shifts because the wavelength of the light changes. In a material where the index of refraction is n$,$ the wavelength is $=/,$where $$is the wavelength in vacuum $($Eq$\mathrm{.}341).$ How many dark bands would there be if the wedge of Example $346$ is filled with water?