Question

A light of wavelength 6000 A in air enters a medium of refractive index 1.5. Inside the medium, its frequency is v and its wavelength is $ \lambda $ (1) $ v=5\times {{10}^{14}}Hz $ (2) $ v=7.5\times {{10}^{14}}Hz $ (3) $ \lambda =4000{\AA} $ (4) $ \lambda =9000{\AA} $

• A. 1, 2 and 3 are correct
• B. 1 and 2 are correct
• C. 2 and 4 are correct
• D. 1 and 3 are correct

Answer 1

Answer: (D)

$ {{\lambda }_{a}}=6000 $
$ {{v}_{a}}=\frac{c}{{{\lambda }_{a}}}=\frac{3\times {{10}^{8}}}{6000\times {{10}^{-10}}} $
$ =5\times {{10}^{14}}Hz $
In water, $ {{\lambda }_{m}}=\frac{{{\lambda }_{a}}}{\mu }=\frac{6000}{1.5}=4000 $