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Two concave lenses L1 and L2 are kept in...

Two concave lenses `L_1 and L_2` are kept in contact with each other. If the space between the two lenses is filled with a material of smaller refractive index, the magnitude of the focal length of the combination

A

becomes undefined

B

remains unchanged

C

increases

D

decreases

Text Solution

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The correct Answer is:
C
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HC VERMA-GEOMETRICAL OPTICS-Objective 1
  1. A point source of light is placed in front of a plane mirror.

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  2. Total internal reflection can take only if

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  3. In image formatiion from spherical mirrors, only paraxial rays are con...

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  4. A point object is placed at distance of 30 cm in front of a convex mi...

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  5. Figure shows two rays A and B beig reflected by a mirror and going as ...

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  6. The image formed by a concave mirror

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  7. Figure shows figure three transparent medi of refractive indices mu1, ...

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  8. Four modifications are suggested in the lens formula to incude the eff...

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  9. A double convex lens has two surfaces of equal radii R and refractive ...

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  10. A point source of light is placed at a distance of 2f from a convergin...

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  11. A parallel beam of light is incident on a converging lens parallel to ...

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  12. A symmetric doule convex lens is cut in two equal parts by a plane per...

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  13. A symmetric doule convex lens is cut in two equal parts by a plane per...

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  14. Two concave lenses L1 and L2 are kept in contact with each other. If t...

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  15. A thin lens is made with as material having refractive index mu=1.5. b...

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  16. A convex lens is made of a material having refractive index 1.2. Both ...

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  17. A point object O is placed on the principal axis of a convex lens of f...

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  18. The rays of different colours fail to converge at a point after going ...

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