Young$$s double$-$slit experiment is performed immersed in water $(=1\mathrm{.}333=1\mathrm{.}333).$ The light source is a He$-$Ne laser, $=632\mathrm{.}9$nm$=632\mathrm{.}9$nm in vacuum. $($a$)$ What is the wavelength of this light in water? $($b$)$ What is the angle for the third order maximum for two slits separated by $0\mathrm{.}100$ mm$.$