IIT JEE , AIEEE Forum - Physics , Optics

kislay

a glass sphere with radius 10 cm has a 5 cm radius spherical hole at its centere.a narrow beam of parallel light is directed radially into the sphere.where if anywhere will the sphere produce an image?the refractive index of glass is 1.50.

ans... 15 cm from left edge..

bvsatyaram

Use formula for "refraction at spherical surfaces".

First consider refraction at the outer spherical surface. If the image forms before it reaches the cavity, then it is the answer. If the image crosses teh cavity, then consider this image as object and find the location of object. If the position of image is within the cavity, then this will be the answer. If the image is beyond the other extreme of the cavity, then consider another refraction at the other spherical surface of the cavity. If this image is formed before it crosses the outer surface of sphere, then that will be the answer. If not, then consider the reflection also at the other outer surface of the sphere. If u find an image out side the sphere, then that is the answer. If not, then no real image is formed.

I hope I've confused u well. :-)

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