CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2008

  • question_answer
    The oscillating frequency of a cyclotron is 10 MHz. If the radius of its dees is 0.5 m, the kinetic energy of a proton, which is accelerated by the cyclotron is

    A)  10.2 MeV      

    B)         2.55 MeV           

    C)  20.4 MeV      

    D)  5.1 MeV

    E)  1.5 MeV

    Correct Answer: D

    Solution :

    KE of charged possible in a cyclotron, \[{{E}_{k}}=\frac{{{q}^{2}}{{B}^{2}}{{r}^{2}}}{2m}\] But frequency \[f=\frac{qB}{2\pi m}\] \[\therefore \]  \[{{E}_{k}}=\frac{{{(2\pi mf)}^{2}}{{r}^{2}}}{2m}=2{{\pi }^{2}}m{{f}^{2}}{{r}^{2}}\] Or \[{{E}_{k}}=2\times {{(3.14)}^{2}}\times 1.67\times {{10}^{-27}}\times {{(10\times {{10}^{6}})}^{2}}\]                                                                      \[\times {{(0.5)}^{2}}\] \[=8.23\times {{10}^{-13}}J\] \[\therefore \,\,{{E}_{k}}\,=\frac{8.23\,\times {{10}^{-13}}}{1.6\,\times {{10}^{-19}}\,}\,=5.1\,\times {{10}^{6}}\,eV=5.1\,MeV\]


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