Question

A tiny insect has been trapped inside a sphere of refractive index 1.5 and radius 1.5 cm. An observer
observes its image 5 mm inside the surface of the sphere. Its actual distance from the surface is
45
mm. Find n.​

Answer 1

Answer:

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Answer 2

Given:

A tiny insect has been trapped inside a sphere of refractive index 1.5 and radius 1.5 cm. An observer  observes its image 5 mm inside the surface of the sphere. Its actual distance from the surface is  45 mm.

To Find:

Find u?

Solution:

here, it is given that-

n1=1.5 , n2=1 , R= 1.5cm , v=(45 - 5)mm=4.0cm

From Lens Formula-

$\dfrac{n_{2} }{v}-\dfrac{n_{1} }{u}=\dfrac{n_{2} -n_{1} }{R}$

therefore,

$\dfrac{1}{4} -\dfrac{1.5}{u} =\dfrac{1-1.5 }{1.5} \\\\3(u-6)=4u(-1)\\3u-18=-4u\\7u=18\\u=2.57cm=25.7mm$

Hence, u is 25.7 cm