JEE Main & Advanced Physics Nuclear Physics And Radioactivity Question Bank Critical Thinking

  • question_answer
    An a-particle of 5 MeV energy strikes with a nucleus of uranium at stationary at an scattering angle of 180o. The nearest distance upto which a-particle reaches the nucleus will be of the order of                            [IIT 1981; AIEEE 2004]

    A)            \[1\,\overset{o}{\mathop{A}}\,\]                                    

    B)            \[{{10}^{-10}}cm\]

    C)            \[{{10}^{-12}}cm\]

    D)            \[{{10}^{-15}}cm\]

    Correct Answer: C

    Solution :

                       At closest distance of approach Kinetic energy = Potential energy                    \[\Rightarrow 5\times {{10}^{6}}\times 1.6\times {{10}^{-19}}=\frac{1}{4\pi {{\varepsilon }_{0}}}\times \frac{(ze)(2e)}{r}\]            For uranium z= 92, so \[r=5.3\times {{10}^{-12}}cm\]          


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