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An object has image thrice of its origin...

An object has image thrice of its original size when kept at `8 cm` and `16 cm` from a convex lens. Focal length of the lens is

A

less than 8 cm

B

8 cm

C

16 cm

D

between 8 and 16 cm

Text Solution

Verified by Experts

The correct Answer is:
D
(d) Magnification,m=`pm3`
We have,`m=f/(f+u)`
For verticle image,`3=f/(f+8)....(i)`
For real image,`-3=f/(f-16)......(ii)`
Solving Eqs. (i) and (ii) we get
f=12 cm
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