Optics Question 775
Question: Refractive index of air is 1.0003. The correct thickness of air column which will have one more wavelength of yellow light $ ( 6000{AA} ) $ than in the same thickness in vacuum is
[RPMT 1995]
Options:
A) 2 mm
B) 2 cm
C) 2 m
D) 2 km
Show Answer
Answer:
Correct Answer: A
Solution:
For vacuum $ t=n{\lambda _{o}} $ …..(i)
For air $ t=(n+1){\lambda _{a}} $ …..(ii)
From equation (i) and (ii) $ t=\frac{\lambda }{\mu -1}=\frac{6\times {{10}^{-7}}}{1.0003-1} $
$ ( \mu =\frac{{\lambda _{o}}}{{\lambda _{a}}} ) $
$ =2\times {{10}^{-3}}m $ = 2mm.
