NEET AIPMT SOLVED PAPER SCREENING 2008

  • question_answer
    The measurement of the electron position is associated with an uncertainty in momentum, which is equal to \[1\times {{10}^{-18}}g\,cm\,{{s}^{-1}}.\]The uncertainty in electron velocity is, (mass of an electron is \[9\times {{10}^{-28}}g\])

    A) \[1\times {{10}^{9}}cm\,{{s}^{-1}}\]                       

    B) \[1\times {{10}^{6}}cm\,{{s}^{-1}}\]       

    C)        \[1\times {{10}^{5}}cm\,{{s}^{-1}}\]                       

    D) \[1\times {{10}^{11}}cm\,{{s}^{-1}}\]

    Correct Answer: A

    Solution :

    Key Idea: \[\Delta x\times \Delta p\ge \frac{h}{4\pi }\]where, \[\Delta p=\] uncertainty in momentum and \[\Delta v=\]uncertainty in velocity Here, \[\Delta p=1\times {{10}^{-18}}g\,cm\,{{s}^{-1}}\] \[m=9\times {{10}^{-28}}\]g \[\Delta v=\frac{\Delta p}{m}=\frac{1\times {{10}^{-18}}}{9\times {{10}^{-28}}}\] \[=1.1\times {{10}^{9}}\] \[\approx 1.0\times {{10}^{9}}\,cm\,{{s}^{-}}\]


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