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Diameter of human eye lens is 2 mm. What will be the minimum distance between two points to resolve them, which are situated at a distance of 50 m from eye? The wavelength of light is 5000 Å.

Asked in CBSE AIPMT 2002 · Human eye and defects of vision

• (1) 2.32 m
• (2) 4.28 mm
• (3) 1.25 cm
• (4) 12.48 cm

Step-by-step solution

Why the other options are wrong

• (1) comes from is more than a hundred times too large; (λ D)/d with these numbers is 1.25×10⁻² m
• (2) comes from is about a third of the right answer and cannot be reached from 5×10⁻⁷, 50 and 2×10⁻³ by any single step
• (4) comes from slipping the millimetre conversion on the pupil: with d=0.2 mm the same formula gives (5×10⁻⁷×50)/(2×10⁻⁴)=0.125 m

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