Optics Question 690
Question: The power of an achromatic convergent lens of two lenses is + 2D. The power of convex lens is + 5D. The ratio of dispersive power of convex and concave lens will be
[Pb. PET 2003]
Options:
A) 5 : 3
B) 3 : 5
C) 2 : 5
D) 5 : 2
Show Answer
Answer:
Correct Answer: B
Solution:
$ P _{1}+P _{2}=2D $ and $ P _{1}=5D, $
So $ P _{2}=-3D $
For achromatic combination $ \frac{{\omega _{1}}}{{\omega _{2}}}=( -\frac{p _{2}}{p _{1}} ) $
$ =-( \frac{-3}{5} )=\frac{3}{5} $
