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Two planoconvex lenses each of the focal...

Two planoconvex lenses each of the focal length of`10cm`&refractive index`3//2`are placed as shwon .In the space left water`(R.I.=4//3)`is filled.Then whole arrangement is in air.The optical power of the system is(in diopters).

A

`6.67 `

B

`-6.67`

C

`33.3`

D

`20`

Text Solution

Verified by Experts

The correct Answer is:
A
`(1)/(v)-(1)/(v)=(1)/(f) implies (1)/((d-u))-(1)/((-u))=(1)/(f)`
`impliesu^(2)-du+df=0 implies d=(u^(2))/((f-u))`
for minimum `d,u=-2f` Hence, `d_(min.)=4f`
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RESONANCE ENGLISH-GEOMATRICAL OPTICS -Exercise-1
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  2. The minimum distance between a real object and its real image formed b...

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  3. Two planoconvex lenses each of the focal length of10cm&refractive inde...

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  4. A plano-convex lens when silvered in the plane side behaves like a con...

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  5. Define: Radius of curvature and centre of curvature

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  6. The focal length of a plano-concave lens is -10 cm , then its focal le...

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  7. A convex lens of focal length 80 cm and a concave lens of focal length...

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  8. The dispersion of light in a medium implies that :

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  9. Critical angle of light passing from glass to air is least for

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  10. A plane glass slab is placed over various coloured letters. The letter...

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  11. A medium has nv = 1.56, nr=1.44. Then its dispersive power is:

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  12. All the listed things below are made of flint glass. Which one of thes...

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  13. Light of wavelenght 4000 A is incident at small angle on a prim of ape...

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  14. A simple microscope has a focal length of 5 cm . The magnification at...

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  15. In a compound microscope, the intermediate image is

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  16. The resolving power of a telesope is more when its objective lens has

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  17. A Galileo telescope has an objective of focal length 100cm and magnif...

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  18. The convex lens is used in-

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  19. The magnifying power of a simple microscope can be increased, if we us...

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  20. The focal length of the objective lens of a compound microscope is

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