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12th Class Physics Electrostatics & Capacitance Question Bank MCQ - Electrostatic Potential and Capacitance

  • question_answer
    A parallel plate capacitor with air between the plates has a capacitance of 10 pF. The capacitance, if the distance between the plates is reduced by half and the space between them is filled with a substance of dielectric constant 4 is:

    A) 80 pF                           

    B) 96pF    

    C) 100 pF                         

    D) 120pF

    Correct Answer: A

    Solution :

    (a) 80pF Here,    \[{{C}_{1}}=\frac{{{\varepsilon }_{0}}A}{d}=10\,pF\] and       \[{{C}_{2}}=K\frac{{{\varepsilon }_{0}}A}{d/2}=\frac{4\times 2{{\varepsilon }_{0}}A}{d}\] \[\left( \because \,\,K=4 \right)\] \[=8\times 10\]                           (using eq.(1)) \[=80\,pF\]


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