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Question
A thin converging glass lens made of glass with refractive index 1.5 has a power of + 5.0 D. When this lens is immersed in a liquid of refractive index n, it acts as a divergent lens of focal length 100 cm. What must be the value of n?
Solution
`"P"_"a"/"P"_"l" = ((mu_"g"/mu_"a" - 1))/((mu_"g"/mu_l - 1)) = 5/(- 100//100)` = - 5
`- 5 (mu_"g"/mu_l - 1) = mu_"g"/mu_"l" - 1`
`(1.5/mu_l - 1) = 1/5 (1.5 - 1)`
`mu_l = 1.5/0.9 = 5/3`
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