NEET Sample Paper NEET Sample Test Paper-11

  • question_answer
    The mass of electron is\[9.11\times {{10}^{-31}}\,kg,\] Planck constant is \[6.626\times {{10}^{-34}}\,Js,\]the uncertainty involved in the measurement of velocity within a distance of \[0.1\,\overset{\text{o}}{\mathop{\text{A}}}\,\]is

    A) \[5.79\times {{10}^{8}}\,m\,{{s}^{-1}}\]        

    B) \[5.79\times {{10}^{5}}\,m\,{{s}^{-1}}\]

    C) \[5.79\times {{10}^{6}}\,m\,{{s}^{-1}}\]        

    D) \[5.79\times {{10}^{7}}\,m\,{{s}^{-1}}\]    

    Correct Answer: C

    Solution :

     By Heisenberg?s uncertainty principle, \[\Delta p\times \Delta x=\frac{h}{4\pi }\]or \[\Delta r\times \Delta x=\frac{h}{4\pi m}\] Given that, \[\Delta x=0.1\overset{\text{o}}{\mathop{\text{A}}}\,=0.1\times {{10}^{-10}}m\] \[m=9.11\times {{10}^{-31}}kg\] \[h=\]planck?s constant \[=6.626\times {{10}^{-34}}\,Js\] \[\pi =3.14\] Thus, \[\Delta r\times 0.1\times {{10}^{-10}}=\frac{6.626\times {{10}^{-31}}}{4\times 3.14\times 9.11\times {{10}^{-31}}}\] \[=5.785\times {{10}^{6}}m{{s}^{-1}}=5.79\times {{10}^{6}}\,m{{s}^{-1}}\]


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