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Ray Optics and Optical Instruments
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Combination of Mirror and Lenses
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The focal length of a lens of refractive
Question
The focal length of a lens of refractive index
μ
is
f
. If the lens is immersed in a liquid of refractive index
μ
then the focal length of lens is
A
2
f
B
2
f
C
infinite
D
zero
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Updated on : 2022-09-05
Solution
Verified by Toppr
Correct option is C)
f
1
=
(
n
−
1
)
(
R
1
1
−
R
2
1
)
where,
n
is refractive index of lens material with respect to its surrounding medium
If lens is immersed in the liquid of refractive index equal to its own then
n
=
1
and hence above equation becomes:
f
1
=
0
⇒
f
=
∞
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