When a ray enters into air from glass slab

When a ray enters into air from glass slab its wavelength increases

            Explanation: As the light enters from denser medium to rarer medium, the speed of light

            Speed of light increases but the frequency remains same.

            The relation between speed of light, wavelength and the frequency is  $\mathrm{v}=\mathrm{\eta \lambda }$

            Where v is the speed of the light

            $\mathrm{\eta }=$Frequency of light

           $\mathrm{\lambda }=$Wave length of the light