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An object is located in a fixed position in front of a screen. Sharp image is obtained on the screen for two positions of a thin lens separated by 10 cm. The size of the images in two situtation are in the ratio 3 : 2. What is the distance between the screen and the object? |
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Answer» 124.5 CM  `implies (m_1)/(m_2) = ((D + d)/(D - d))^(2)` `implies 3/2 = ((D + 10)/(D - 10))^(2)` `3(D - 10)^2 = 2 (D + 10)^2` `3(D^2 + 100 - 20D) = 2(D^2 + 20 D + 100)` `D^2 - 100 D + 100 = 0` `D = 99 cm` |
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