RAJASTHAN ­ PET Rajasthan PET Solved Paper-2008

  • question_answer
    The intensity distribution of X-rays from two coolidge tubes operated on different voltages \[{{V}_{1}}\]and\[{{V}_{2}}\]and using different target materials of atomic numbers\[{{Z}_{1}}\]and\[{{Z}_{2}}\]is shown in the figure. Which of the following inequalities is true?

    A)  \[{{V}_{1}}>{{V}_{2}}\]and \[{{Z}_{1}}<{{Z}_{2}}\]

    B) \[{{V}_{1}}>{{V}_{2}}\]and \[{{Z}_{1}}>{{Z}_{2}}\]

    C)  \[{{V}_{1}}<{{V}_{2}}\]and\[{{Z}_{1}}>{{Z}_{2}}\]

    D) \[{{V}_{1}}={{V}_{2}}\]and\[{{Z}_{1}}<{{Z}_{2}}\]

    Correct Answer: A

    Solution :

     \[{{\lambda }_{\min }}=\frac{hc}{eV}\] \[\Rightarrow \] \[\lambda \propto \frac{1}{V}\] \[(\because {{\lambda }_{2}}>{{\lambda }_{1}})\] \[\Rightarrow \] \[{{V}_{1}}>{{V}_{2}}\] From Moseley's law\[\sqrt{v}=a(Z-b)\] \[v\propto {{(Z-1)}^{2}}\] \[\Rightarrow \] \[\lambda \propto \frac{1}{{{(Z-1)}^{2}}}\] \[\left[ \because v\propto \frac{1}{\lambda } \right]\] According to diagram\[{{\lambda }_{1}}>{{\lambda }_{2}}\] \[\Rightarrow \] \[{{Z}_{2}}>{{Z}_{1}}\]


You need to login to perform this action.
You will be redirected in 3 sec spinner