A) \[4f\]
B) \[2f\]
C) \[f\]
D) \[0.5f\]
Correct Answer: B
Solution :
Consider the type of lenses shown below: For bi-convex lens, focal length is given by \[\frac{1}{{{f}_{b}}}=(\mu -1)\left( \frac{1}{R}+\frac{1}{R} \right)=\frac{2(\mu -1)}{R}\] For plano-convex lens focal length is given by \[\frac{1}{{{f}_{p}}}=(\mu -1)\left( \frac{1}{R}+\frac{1}{R} \right)=\frac{(\mu -1)}{R}\] \[\Rightarrow \]\[\frac{{{f}_{b}}}{{{f}_{p}}}=\frac{\frac{R}{2(\mu -1)}}{\frac{R}{(\mu -1)}}=\frac{1}{2}\Rightarrow {{f}_{p}}=2{{f}_{b}}=2f\]You need to login to perform this action.
You will be redirected in
3 sec