If light incident in air at an angle of incidence ${45}^0$ and refracted in other medium at an angle of refraction ${30}^0.$ If wavelength in air is ${\lambda }_1$ and frequency is ${\upsilon }_1$ and in medium wavelength is  ${\lambda }_2$and frequency is ${\upsilon }_2$, relation between ${\lambda }_{2}and{\lambda }_1$ is  ${\lambda }_2=\frac{{\lambda }_1}{\sqrt{x}}$ then x is