A monochromatic light wave with wavelength ${\lambda }_1$ and frequency ${\nu }_1$ in air enters another medium. If the angle of incidence and angle of refraction at the interface are $45°$ and $30°$ respectively, then the wavelength ${\lambda }_2$ and frequency ${\nu }_2$ of the refracted wave are:

• A

  ${\lambda }_2=\sqrt{2}{\lambda }_1,{\nu }_2={\nu }_1$
• B

  ${\lambda }_2={\lambda }_1,{\nu }_2=\frac{1}{\sqrt{2}}{\nu }_1$
• C

  ${\lambda }_2={\lambda }_1,{\nu }_2=\sqrt{2}{\nu }_1$
• Correct answer
  D

  ${\lambda }_2=\frac{1}{\sqrt{2}}{\lambda }_1,{\nu }_2={\nu }_1$

Hence, the correct answer is option: 'D'.