InterviewSolution
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InterviewSolution
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In a compound microscope, the focal length of the objective and the eye lens are `2.5 cm` and `5 cm` respectively. An object is placed at `3.75cm` before the objective and image is formed at the least distance of distinct vision, then the distance between two lenses will be `( i.e.` length of the microscope tube )A. 11.67 cmB. 12 cmC. 12.75 cmD. 13 cm |
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Answer» Correct Answer - A For objective lens, `(1)/(f_(o))=(1)/(v_(o))-(1)/(u_(o))` Using proper sign convention, `(1)/(+2.5)=(1)/(v_(o))-(1)/((-3.75))rArr v_(o)=7.5 cm` For eye lens, `(1)/(f_(e ))=(1)/(v_(e ))-(1)/(u_(e ))` `(1)/(+5)=(1)/((-25))-(1)/(u_(e )) rArr u_(e )=-4.16 cm` or `" " |u_(e )|=4.16 cm` `therefore` Distance between the lens `= 7.5+4.16=11.67 cm` |
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