EAMCET Medical EAMCET Medical Solved Paper-2010

  • question_answer
    The plates in a parallel plate capacitor are separated by a distance d with air as the medium between the plates. In order to increase the capacity by 66% a dielectric slab of dielectric constant 5 is introduced between the plates. What is the thickness of the dielectric slab?

    A)                  \[\frac{d}{4}\]                                 

    B)                  \[\frac{d}{2}\]

    C)                  \[\frac{5d}{8}\]                                               

    D)                  \[d\]

    Correct Answer: B

    Solution :

                     The capacity in air                 \[C=\frac{{{\varepsilon }_{0}}A}{d}\]                 The capacity when dielectric slab of dielectric constant 5 is introduced between the plates                 \[C=\frac{{{\varepsilon }_{0}}A}{d-t+\frac{t}{5}}\]                 \[\therefore \]  \[\frac{C}{C}=\frac{d-t+\frac{t}{5}}{d}\]                 \[C=\frac{166}{100}C\]                 \[\frac{100}{166}=\frac{d-t+\frac{t}{5}}{d}=\frac{d-\frac{4t}{5}}{d}\]                 or            \[100d=166d-166\left( \frac{4t}{5} \right)\]                 \[166\left( \frac{4t}{5} \right)=66d\]                 \[t=\frac{66d\times 5}{166\times 4}=\frac{d}{2}\]           


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