NEET Sample Paper NEET Sample Test Paper-75

  • question_answer
    If a proton having kinetic energy 0.5 MeV approaches a gold nucleus. Then, the distance of closest approach w be \[\left( Z=79 \right)\]

    A)  \[2.3\,\,\times \,\,1{{0}^{-10}}m\]        

    B)  \[2.3\,\,\times \,\,1{{0}^{-14}}m\]

    C)  \[4.8\,\,\times \,\,1{{0}^{-10}}m\]        

    D)  \[4.8\,\,\times \,\,1{{0}^{-14}}m\]

    Correct Answer: B

    Solution :

    As, \[E=0.5\,Me\,V=0.5\times 1.6\times 1{{0}^{-}}^{13}\,J\] Now,     \[E=\frac{1}{4\pi {{\varepsilon }_{0}}}\frac{(Ze)(e)}{{{r}_{0}}}\] \[\therefore \,\,\,\,\,\,\,\,\,\,\,{{r}_{0}}=\frac{1}{4\pi {{\varepsilon }_{0}}}\frac{Z{{e}^{2}}}{E}=\frac{9\times {{10}^{9}}\times 79{{(1.6\times {{10}^{-19}})}^{2}}}{5\times 1.6\times {{10}^{-13}}}\]\[=\,\,2.3 \times \,\,1{{0}^{-}}^{14}\,m\]


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