BHU PMT BHU PMT Solved Paper-2004

  • question_answer
    According   to   Heisenberg's   uncertainty principle, the product of uncertainties in position and velocities for an electron of mass \[9.1\times {{10}^{-31}}kg\]is:

    A)  \[2.8\times {{10}^{-3}}{{m}^{2}}{{s}^{-1}}\]       

    B) \[3.8\times {{10}^{-5}}{{m}^{2}}{{s}^{-1}}\]

    C)  \[5.8\times {{10}^{-5}}{{m}^{2}}{{s}^{-1}}\]       

    D)  \[6.8\times {{10}^{-6}}{{m}^{2}}{{s}^{-1}}\]

    Correct Answer: C

    Solution :

    Key Idea: We will use formula\[\Delta x\times \Delta p=\frac{h}{4\pi }\]to solve problem. \[\Delta x\times \Delta p=\frac{h}{4\pi }\] \[\Delta x\times m\Delta v=\frac{h}{4\pi }\] \[\Delta x\times \Delta v=\frac{h}{4\pi m}\] \[\Delta x=\]uncertainty in position \[\Delta v=\]uncertainty in velocity h = Planck's constant\[=6.63\times {{10}^{-34}}kg\text{ }{{m}^{2}}{{s}^{-1}}\] m= mass of electron\[=9.1\times {{10}^{-31}}kg\] \[\therefore \]  \[\Delta x\times \Delta v=\frac{6.63\times {{10}^{-34}}}{4\times 3.14\times 9.1\times {{10}^{-31}}}\]                 \[=5.8\times {{10}^{-5}}{{m}^{2}}{{s}^{-1}}\]


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