NEET Sample Paper NEET Sample Test Paper-74

  • question_answer
    If the mass of electron is \[9.11 \times  1{{0}^{-}}^{31}\,kg\], Planck?s constant is \[6.626 \times  1{{0}^{-}}^{34}\,J-s\] and uncertainty m position is \[0.1\,\overset{{}^\circ }{\mathop{A}}\,\], then uncertainty in velocity is

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

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

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

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

    Correct Answer: C

    Solution :

    According to Hisenberg uncertainty principle \[\Delta x\cdot \Delta p=\frac{h}{4\pi }\] \[\Delta x\times \,\,m\Delta v=\frac{h}{4\pi }\] \[\Delta x\times \,\,\Delta v=\frac{h}{4\pi m}\] \[\Delta v=\frac{h}{4\pi m\cdot \Delta x}\] \[=\,\,\,\,\frac{6.626\times {{10}^{-34}}}{4\times 3.14\times 9.11\times {{10}^{-}}^{31}\times 0.1\times {{10}^{-}}^{10}}\] \[=\,\,\,\,\frac{6.626\times {{10}^{-34}}}{4\times 3.14\times 0.1\times {{10}^{-}}^{41}}\] \[=\,\,\,\,\frac{6.626\times {{10}^{-34\,+\,41}}}{0.4\times 3.14}=\frac{6.626}{0.4\times 3.14}\times {{10}^{+7}}\] \[=\,\,\,5.79\times 1{{0}^{6}}m/s\]


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