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NEET AIPMT SOLVED PAPER SCREENING 2004

  • question_answer
    A telescope has an objective lens of 10 cm diameter and is situated at a distance of one kilometre from two objects. The minimum distance between these two objects, which can be resolved by the telescope, when the mean wavelength of light is \[5000\overset{\text{o}}{\mathop{\text{A}}}\,,\], of the order of:                                                                       

    A) 0.5m       

    B) 5m                                 

    C) 5 mm      

    D) 5 cm

    Correct Answer: C

    Solution :

    Resolving limit of telescope is \[\theta \propto \frac{x}{D}=\frac{\lambda }{d}\] \[\Rightarrow \]       \[x=\frac{\lambda D}{d}\] Given, \[\lambda =5000\,\text{{ }\!\!\mathrm{\AA}\!\!\text{ }}\,\text{=}\,\text{5000}\times {{10}^{-10}}m,\] \[\text{D}=\text{1 km}=\text{1}000\text{m},\] \[d=10\,cm\,=0.1\,\,m,\] Hence, \[x=\frac{5000\times {{10}^{-10}}\times 1000}{0.1}\] \[=5\times {{10}^{-3}}m\] \[=5\,\,mm\]


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