Q.

A monochromatic light of frequency 5×1014 Hz travelling through air, is incident on a medium of refractive index '2'. Wavelength of the refracted light will be:          [2025]

1 300 nm  
2 600 nm  
3 400 nm  
4 500 nm  

Ans.

(1)

Wave speed, v=fλ

As μ = 2 therefore; speed c→c2

λmedium=c2f=3×1082×5×1014=3×10–7 m

               =3×10–7×109 nm=300 nm