VMMC VMMC Medical Solved Paper-2003

  • question_answer
    What is the de-Broglie wavelength of the\[\alpha \]-particle accelerated through a potential difference of V volt? (mass of \[\alpha \] particle \[=6.6465\,\times {{10}^{-27}}\,kg\])

    A) \[\frac{0.287}{\sqrt{V}}\overset{0}{\mathop{A}}\,\]      

    B)        \[\frac{12.27}{\sqrt{V}}\overset{0}{\mathop{A}}\,\]      

    C)        \[\frac{0.101}{\sqrt{V}}\overset{0}{\mathop{A}}\,\]      

    D)        \[\frac{0.202}{\sqrt{V}}\overset{0}{\mathop{A}}\,\]

    Correct Answer: C

    Solution :

    de-Broglie wavelength is given by \[\lambda =\frac{h}{\sqrt{2mE}}\] Since, charge on \[\alpha -\]particle =2e and if it is accelerated through V volts, then its K.E. \[E=2\,\,eV\]                     \[\therefore \]  \[\lambda =\frac{h}{\sqrt{2m.2eV}}\] or            \[\lambda =\frac{6.63\times {{10}^{-34}}}{\sqrt{4\times 6.6465\times {{10}^{-27}}\times 1.6\times {{10}^{-19}}\times V}}m\] \[=\frac{3.315\times {{10}^{-34}}}{\sqrt{1.6\times 6.6465\times {{10}^{-25}}\sqrt{V}}}m\] \[=\frac{0.3315\times {{10}^{-10}}}{\sqrt{10.6344}}.\frac{1}{\sqrt{V}}m\] \[=\frac{0.101}{\sqrt{V}}\overset{\text{o}}{\mathop{\text{A}}}\,\]


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