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12th Class Physics Electrostatics & Capacitance Question Bank Case Based (MCQs) - Electric Potential and Capacitance

  • question_answer
    A parallel plate capacitor with air between the plates has a capacitance of 8 pF. The separation between the plates is now reduced half and the space between them is filled with a medium of dielectric constant 5. Calculate the value of capacitance of the capacitor in second case.

    A) 8 pF

    B) 10 pF

    C) 80 pF

    D) 100 pF

    Correct Answer: C

    Solution :

    Capacitance of the capacitor with air between plates \[C'=\frac{{{\varepsilon }_{0}}A}{d}=8\,pF\] When the capacitor is filled with dielectric (k = 5) between its plates and the distance between the plates is reduced by half, capacitance become \[C=\frac{{{\varepsilon }_{0}}kA}{d/2}=\frac{{{\varepsilon }_{0}}\times 5\times A}{d/2}=10\,C'\] \[=10\times 8=80\,pF\].


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