KVPY Sample Paper KVPY Stream-SX Model Paper-24

  • question_answer
    A parallel plate capacitor is of area \[6\,\,C{{m}^{2}}\] and a separation 3 mm. The gap is filled with three dielectric materials of equal thickness (see figure) with dielectric constants \[{{K}_{1}}=10,\] \[{{K}_{2}}=12\] and \[{{K}_{3}}=14.\]The dielectric constant of a material which when fully inserted in above capacitor, gives same capacitance would be:

    A) 4

    B) 14

    C) 12        

    D) 36

    Correct Answer: C

    Solution :

    \[{{C}_{net}}={{C}_{1}}+{{C}_{2}}+{{C}_{3}}\]
    \[\frac{kA{{E}_{o}}}{d}={{k}_{1}}\left( \frac{A}{3} \right)\frac{{{E}_{o}}}{d}+{{k}_{2}}\left( \frac{A}{3} \right)\frac{{{E}_{o}}}{d}+{{k}_{3}}\left( \frac{A}{3} \right)\frac{{{E}_{o}}}{d}\]
    \[k=\frac{{{k}_{1}}+{{k}_{2}}+{{k}_{3}}}{3}=12.\]


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