A beam of light propagates through medium 1 and falls onto another medium 2, at an angle \[{{\alpha }_{1}}\] as shown in figure. After that, it propagates in Medium 2 at an angle \[{{\alpha }_{2}}\] as shown. The light's wavelength in medium 1 is \[{{\lambda }_{1}}\]. What is the wavelength of light in medium 2?

• A. \[\frac{\sin \,{{\alpha }_{1}}}{\sin {{\alpha }_{2}}}{{\lambda }_{1}}\]  
• B. \[\frac{\sin \,{{\alpha }_{2}}}{\sin {{\alpha }_{1}}}{{\lambda }_{1}}\]
• C. \[\frac{\cos \,{{\alpha }_{1}}}{\cos {{\alpha }_{2}}}{{\lambda }_{1}}\] 
• D. \[\frac{\cos \,{{\alpha }_{2}}}{\cos {{\alpha }_{1}}}{{\lambda }_{1}}\]