A lens is made of flint glass (refractive index = 1.5). When the lens is immersed in a liquid of refractive index 1.25, the focal length
a)
Increase by a factor of 1.25
b)
Increases by a factor of 2.5
c)
Increases by a factor of 1.2
d)
Decreases by a factor of 1.2
A lens is made of flint glass (refractive index = 1.5). When the lens is immersed in a liquid of refractive index 1.25, the focal length
a)
Increase by a factor of 1.25
b)
Increases by a factor of 2.5
c)
Increases by a factor of 1.2
d)
Decreases by a factor of 1.2
Question ID - 152380 | SaraNextGen Top Answer
A lens is made of flint glass (refractive index = 1.5). When the lens is immersed in a liquid of refractive index 1.25, the focal length
a)
Increase by a factor of 1.25
b)
Increases by a factor of 2.5
c)
Increases by a factor of 1.2
d)
Decreases by a factor of 1.2
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A lens is made of flint glass (refractive index = 1.5). When the lens is immersed in a liquid of refractive index 1.25, the focal length |
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a) |
Increase by a factor of 1.25 |
b) |
Increases by a factor of 2.5 |
|
c) |
Increases by a factor of 1.2 |
d) |
Decreases by a factor of 1.2 |
1 Answer
127 votes
Answer Key / Explanation : (b) -
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(b) Lens-maker’s formula is given by
If the lens is immersed in a liquid of refractive index
Here, Dividing Eq. (i) by Eq. (ii), we have
Hence, focal length increases by a factor of 2.5. |
then
is refractive index of glass w.r.t liquid
127 votes
Answer Link
127