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Point source of light is placed 4 m below water surface in the medium (water) havingrefractive index 5/3. A disc is placed on the water surface such that it blocks the light coming out of water completely so minimum diameter of disc = ........... |
Answer» Solution :`n=(1)/(sinC)` `thereforen=((r^2+h^2)^(1/2))/(r)` `(5/3)^2xxr^2=r^2+h^2` `therefore(25)/(9)xxr^2=r^2+h^2` `therefore25r^2=9r^2+9h^2` `therefore 16r^2=9h^2` `therefore 4r=3h` `thereforer=(3h)/(4)` `therefore r=(3xx4)/(4)` `therefore r=3`m `therefore` DIAMETER =6m |
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