BCECE Medical BCECE Medical Solved Papers-2011

  • question_answer
    A \[6\times {{10}^{-4}}F\] parallel plate air capacitor is connected to a 500 V battery. When air is replaced by another dielectric material, \[7.5\times {{10}^{-4}}C\] charge flows into the capacitor. The value of the dielectric constant of the material is

    A)  1.5   

    B)  2.0  

    C)  1.0025

    D)  3.5

    Correct Answer: C

    Solution :

                    \[{{q}_{0}}{{C}_{0}}{{V}_{0}}\] and        \[q=C{{V}_{0}}\]                 \[\therefore \] \[\Delta q=q-{{q}_{0}}(C-{{C}_{0}}){{V}_{0}}\] or            \[\Delta q=({{\varepsilon }_{r}}{{C}_{0}}-{{C}_{0}}){{V}_{0}}\] or            \[\Delta q=({{\varepsilon }_{r}}-1){{C}_{0}}{{V}_{0}}\] ... (i) Here,     \[\Delta q=7.5\times {{10}^{-4}}C\] and        \[{{V}_{0}}=500\,\,V\] Putting the values in Eq.(i), we get \[{{\varepsilon }_{r}}=1.0025\]


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