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Two thin lenses of focal length 20 cm an...

Two thin lenses of focal length 20 cm and 25 cm are placed in contact. The effective power of combination is

A

9 diapter

B

`1/9` diapter

C

`1/45` diopter

D

45 diopter

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The correct Answer is:
A
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BINA LIBRARY-Optics-I-EXERCISE
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  2. The refractive index of a medium is 1.8. A bubble lies in this medium ...

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  3. When light travels from glass to air, there is no change in its

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  4. The lateral shift produced in a parallel sided glass slab depends on

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  5. What is optical fibres? What principle is used in it?

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  6. The refractive index of an equilateral prism is 'sq.root 3' . What is ...

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  7. The minimum distance between an object and its real image is

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  8. Critical angle of light passing from glass to air is minimum for

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  9. The critical angle for a medium is 60°. Then the refractive index of t...

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  10. In which of the following cases total internal reflection can not be o...

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  11. The distance between the object and its real image formed by a convex ...

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  12. The focal length of a lens depends upon

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  13. A contact combination is made of a thin convex lens (f = 9 cm) and a t...

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  14. Two thin lenses of focal length 20 cm and 25 cm are placed in contact....

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  15. A lens behaves as a converging lens in air and a diverging lens in wat...

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  16. An eye has a defect of myopia if it does not see

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  17. For removal of hypermetropia, one should use

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  18. On increasing the tube-length of a compound microscope its magnifying ...

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  19. A sharp image is observed through a compound microscope. Now if the ey...

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  20. A convex lens of focal length 10 cm is used as a simple microscope. It...

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