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Two lenses of focal lengths 20 cm and - ...

Two lenses of focal lengths `20 cm and - 40 cm` are held in contact. The image of an object at infinity will be formed by the combination at

A

`oo`

B

`20cm`

C

`40 cm`

D

`60 cm`

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The correct Answer is:
C
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PRADEEP-OPTICS-Exercise
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  2. One dioptre is the power of a lens of facal length

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  3. Two lenses of focal lengths 20 cm and - 40 cm are held in contact. The...

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  4. Refraction of light is the phenomenon of………. When it…………. .

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  5. The basic cause of refraction is…………in going…………. .

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  6. The sun is visible to us before actual………….and after………. . This is bec...

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  7. Total internal reflection of light is the phenomenon of………..into……..fr...

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  8. For toat internal reflection, light must travel……………to………….. .

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  9. Total internal reflection will occure only when………………in………….medium is…...

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  10. Mirage is accounted for by………….. .

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  11. When reflection occurs from denser to………….., then (mu(2))/(mu(1)) = ……...

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  12. For a double convex lens R(1) is………….. And R(2) is…………… . Therefore, i...

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  13. One dioptre is……………of focal length……… .

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  14. A mark is made on the bottom of beaker and a microscope is focussed on...

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  15. Calculate the speed and wvaelength of light (i) in glass (ii) in air, ...

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  16. The refractive index of diamond is 2.47 and that of glass is 1.51. How...

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  17. A pond of depth 20 cm is half filled with an oil of mu = 1.4 and the o...

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  18. A ray of light is incident at an angle of 60^(@) on one face of a rect...

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  19. In Fig. find the maximum angle i for which light suffers total interna...

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