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

  • question_answer
    The number of revolutions per second made by an electron in the first Bohr orbit of hydrogen atom is of the order of  [AMU 1995]

    A)            \[{{10}^{20}}\]                     

    B)            \[{{10}^{19}}\]

    C)            \[{{10}^{17}}\]                     

    D)            \[{{10}^{15}}\]

    Correct Answer: D

    Solution :

               \[mvr=\frac{h}{2\pi }\](for first orbit)                    \[\Rightarrow m\omega {{r}^{2}}=\frac{h}{2\pi }\Rightarrow m\times 2\pi \nu \times {{r}^{2}}=\frac{h}{2\pi }\]\[\Rightarrow \nu =\frac{h}{4{{\pi }^{2}}m{{r}^{2}}}\]            \[=\frac{6.6\times {{10}^{-34}}}{4{{(3.14)}^{2}}\times 9.1\times {{10}^{-31}}\times {{(0.53\times {{10}^{-10}})}^{2}}}\]\[=6.5\times {{10}^{15}}\frac{rev}{sec}\]


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