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CBSE Class 9 Answered

If you read a book placed at distance of 35.0 cm from your eye and the distance from eye lens to retina is 19.0 mm . Find the focal length of the eye lens plzzzzzzzzzzzzzzz fast

Asked by Amber | 29 Apr, 2014, 10:52: AM
answered-by-expert Expert Answer
Human Eye lens is a convex lens.
Object distance = u = -35 cm = -350 mm   ( u is always negative for convex lens)
Image distance = v = 19 mm
 
According to lens formula,
 
1 over f equals 1 over v minus 1 over u 1 over f equals 1 over 19 minus fraction numerator 1 over denominator left parenthesis minus 350 right parenthesis end fraction 1 over f equals 1 over 19 plus 1 over 350 space space space space space space equals fraction numerator 19 plus 350 over denominator 19 cross times 350 end fraction space 1 over f equals 369 over 6550 rightwards double arrow f equals 6550 over 369 rightwards double arrow f almost equal to 18 space m m
Answered by | 29 Apr, 2014, 11:09: AM

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