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A lens having focal length f and apertur...

A lens having focal length f and aperture of diameter `d//2` in the central region of the lens is covered by a black paper.Focal length of the lens and intensity of image image now will be respectively

A

`f//2,I//2`

B

`f,I//4`

C

`3f//4,I//2`

D

`f,3I//4`.

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MODERN PUBLICATION-UNIT TEST -06-EXERCISE
  1. A beam of light is incident on a convex lens parallel to its principal...

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  2. The plane face of the plano-convex lens of focal length 20 cm is silve...

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  3. A lens having focal length f and aperture of diameter d//2 in the cent...

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  4. A beam of parallel rays is brought to focus by a plano-convex lens.A ...

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  5. Large aperture of lens results in

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  6. The spherical abberation in a lens may be inimised by designing of th...

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  7. A glass prism placed in a homogeneous transparent medium will deivatie...

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  8. Angle of minimum deviation for a prism of refractive index 1.5 is equa...

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  9. Yellow light is refracted through a prism producing minimum deviation ...

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  10. The figures represent three cases of ray passing through a prism of re...

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  11. The refracting angle of a prism is A and the refractive index of its m...

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  12. A prism splits a beam of white ligth into its seven constituent colour...

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  13. A narrow beam fo white ligth passes throuugh a glass slab havig paral...

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  14. Refractive indices of a prism material for two wavelengths are 1.66 an...

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  15. When a glass prism is placed inside water,its dispersive power

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  16. During dispersion of white light by prism placed in air,

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  17. The figure shows the view through the eye-piece of a prism spectromete...

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  18. One cannot see through fog, because:

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  19. The sky would appear red instead of blue,if

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  20. What is the cause of formation of a rainbow?

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