InterviewSolution
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InterviewSolution
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(a) With the help of a suitable ray diagram, derive the mirror formula for a concave mirror. (b) The near point of a hypermetropic person is 50 cm from the eye. What is the power of the lens required to enable the person to read clearly a book held at 25 cm from the eye ? |
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Answer» Solution :(c ) `f_(0)=1.25cm` `f_(0)=5CM` `u_(0)=-2.5cm` `(1)/(f_(0))=(1)/(v_(0))-(1)/(u_(0))` `(1)/(v_(0))=(1)/(f_(0))+(1)/(u_(0))=(1)/(1.25)+((-1)/(2.5))` `=(1)/(1.25)-(10)/(25)` `v_(0)=2.5cm` As the final image is formed at infinity, it means thatthe object must be placed at the focus of eyepiece. Therefore, the DISTANCE between objective lens and eyepiece `=v_(0)+f_(E)` `=2.5+5` `=7.5cm` |
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