$8)$ A soap film $($n $=1\mathrm{.}33)$ is $479\mathrm{.}4$ nm thick and lies on a glass plate $($n $=1\mathrm{.}52).$ Sunlight, whose wavelengths $($in vacuum$)$ extend from $380$ to $750$ nm$,$ travels through the air and strikes the film perpendicularly. For which wavelength in this range does destructive interference cause the film to look dark in reflected light?