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A thin equiconvex lens has focal length ...

A thin equiconvex lens has focal length 10 cm and refractive index 1.5 . One of its faces is now silvered and for an object placed at a distance u in front of it, the image coincides with the object. The value of u is

A

10cm

B

5cm

C

20cm

D

15cm

Text Solution

Verified by Experts

The correct Answer is:
B
`1/F=1/(f_(1)) + 1/F_(2)) + 1/(f_(3)),`
`1/F=(2(mu-1))/R + (2(mu-1))/R + 2R`, then `1/F=1/v-1/u`
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NARAYNA-RAY OPTICS AND OPTICAL INSTRAUMENTS -EXERCISE-2 (C.W)(REFRACTION THROUGH SPHERICAL SURFACES )
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