Optics Question 683
Question: A double convex lens $ (R _{1}=R _{2}=10cm) $
$ (\mu =1.5) $ having focal length equal to the focal length of a concave mirror. The radius of curvature of the concave mirror is
[Orssia PMT 2004]
Options:
A) 10 cm
B) 20 cm
C) 40 cm
D) 15 cm
Show Answer
Answer:
Correct Answer: B
Solution:
$ \frac{1}{f}=(\mu -1)( \frac{1}{R _{1}}-\frac{1}{R _{2}} ) $ = $ (1.5-1)( \frac{1}{10}+\frac{1}{10} )=\frac{1}{10} $
Therefore f = 10 cm \ Radius of curvature of concave mirror = 2f = 20 cm.
