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A concave lens forms the image of an obj...

A concave lens forms the image of an object such that the distance between the object and image is `10 cm` and the magnification produced is `1//4`. The focal length of the lens will be

A

`8.6 cm`

B

`6.2 cm`

C

`10 cm`

D

`4.4 cm`

Text Solution

Verified by Experts

The correct Answer is:
D
Concave lens forms the virtual image of a real object.
So let `u=-4x `and `v=-x`
then `3x=10cm`
or `x=(10)/(3)cm`
`:. u=-(40)/(3)cm `and `v=-(10)/(3)cm`
Substituting in `(1)/(f)=(-3)/(10)+(3)/(40)`
or `f=-(40)/(9)` or `f=-4.4 cm`
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Knowledge Check

  • A cocave lens forms the image of an object such that the distance between the object and image is 10 cm and the magnification produced is 1/4. the focal length of the lens will be

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