A) 20 cm
B) 40 cm
C) 30 cm
D) 10 cm
Correct Answer: D
Solution :
The focal length of the plano-convex lens is 20 cm with the plane surface being silvered. So, the net power of the lens is given by \[P=\frac{1}{f}\times 2=\frac{2}{f}\] Thus, the net focal length is \[\frac{f}{2}=\frac{20}{2}=10\,cm\]You need to login to perform this action.
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