NEET AIPMT SOLVED PAPER 2002

  • question_answer
                    Diameter of human eye lens is 2mm. 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 \[5000\overset{\text{o}}{\mathop{\text{A}}}\,\]:

    A)                                                                                                                                                                                            2.32 m       

    B)                 4.28 mm              

    C)                 1.25 cm    

    D)                 12.48 cm

    Correct Answer: C

    Solution :

                    Key Idea: Angular limit of resolution of eye is the ratio of wavelength of light to diameter of eye lens.                 Angular limit of resolution of eye                 \[=\frac{Wavelength\,of\,light}{Diameter\,of\,eye\,lens}\]                 \[i.e.,\theta =\frac{\lambda }{d}...(i)\]                 If y is the minimum resolution between two objects at distance D from eye, then                 \[\theta =\frac{y}{D}....(ii)\]                 From Eqs. (i) and (ii), we have                 \[\frac{y}{D}=\frac{\lambda }{d}\]                 \[ory=\frac{\lambda D}{d}....(iii)\]                 Given, \[\lambda \] \[=5000\overset{\text{o}}{\mathop{\text{A}}}\,=5\times {{10}^{-7}}m,\,\,D=50\,m,\]                 \[d=2\,mm=2\times {{10}^{-3}}m\]                 Substituting in Eq. (iii), we get                 \[y=\frac{5\times {{10}^{-7}}\times 50}{2\times {{10}^{-3}}}\]                 \[=12.5\times {{10}^{-3}}\,m\]                 \[=1.25\,cm\]


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