Q15 of 52 Page 432

A farsighted person cannot see objects placed closer to 50 cm. Find the power of the lens needed to see the objects at 20 cm.

Given that


Far point where object is placed ,u= -20cm


Distance between eye-lens and retina = v = -50 cm


Then using lens formula, the maximum focal length can be calculated as-



Substituting the values,




Now the Power of the lens becomes-



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