2. Solved Papers
  3. Punjab Medical

Punjab Medical Punjab - MET Solved Paper-2003

  • question_answer
    A student can distinctly see the object upto a distance\[15\,\,cm\]. He wants to see the black board at a distance of\[3\,\,m\]. Focal length and power of lens used respectively will be:

    A) \[-4.8\,\,cm,\,\,-3.3\,\,D\]

    B) \[-5.8\,\,cm,\,\,-4.3\,\,D\]

    C) \[-7.5\,\,cm,\,\,-6.3\,\,D\]

    D) \[-15.8\,\,cm,\,\,-6.33\,\,D\]

    Correct Answer: D

    Solution :

    The student should use a lens which forms image at distance of \[15\,\,cm\] of the object placed at \[3m\] i.e., object distance \[u=3m=300cm\],    image    distance From lens formula\[\frac{1}{v}-\frac{1}{u}=\frac{1}{f}\] we get  \[\frac{1}{-15}-\frac{1}{-300}=\frac{1}{f}\] or            \[\frac{1}{f}=\frac{1}{300}-\frac{1}{15}=-\frac{19}{300}\] or            \[f=\frac{-300}{19}\]                 \[=-15.8\,\,m\]                                 (concave lens) Now power of the lens is                 \[P=\frac{1}{f}=\frac{1}{-015.8}\]


You need to login to perform this action.
You will be redirected in 3 sec spinner