A) Concave lens of 20 cm focal length
B) Convex lens of 20 cm focal length
C) Concave lens of 12 cm focal length
D) Convex lens of 12 cm focal length
Correct Answer: A
Solution :
For viewing far objects, concave lenses are used and for concave lens u = wants to see \[=-\,60\,cm\]; v = can see\[=-\,15\,cm\] so from \[\frac{1}{f}=\frac{1}{v}-\frac{1}{u}\]\[\Rightarrow f=-\,20\,cm\].You need to login to perform this action.
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