JCECE Engineering JCECE Engineering Solved Paper-2014

  • question_answer
    A dust particle has mass equal to\[{{10}^{-11}}g\], diameter \[{{10}^{-4}}cm\] and velocity\[{{10}^{-4}}cm/s\]. The error in measurement of velocity is\[0.1\,\,%\]. What will be the uncertainty in its position?

    A) \[0.527\times {{10}^{10}}cm\]   

    B) \[5.27\times {{10}^{9}}cm\]

    C)  \[0.527\times {{10}^{-15}}cm\]

    D)  \[0.527\times {{10}^{-9}}cm\]

    Correct Answer: D

    Solution :

    \[v={{10}^{-4}}cm\,\,{{s}^{-1}}\] \[\therefore \]  \[\Delta v=\frac{0.1\times {{10}^{-4}}}{100}\](due to \[1%\] error)                 \[=1\times {{10}^{-7}}cm\,\,{{s}^{-1}}\] Now,     \[\Delta v\cdot \Delta x=\frac{h}{4\pi m}\] \[\therefore \]  \[\Delta x=\frac{6.626\times {{10}^{-27}}}{4\times 3.14\times {{10}^{-11}}\times {{10}^{-7}}}\]                      \[=0.527\times {{10}^{-9}}cm\]


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