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Chhattisgarh PMT Chhattisgarh PMT Solved Paper-2011

  • question_answer
    The capacitance of an air capacitor is \[15\mu F\] and the separation between the parallel plates is 6 mm. A copper plate of 3 mm thickness  is  introduced  symmetrically between the plates. The capacitance now becomes

    A)  \[5\text{ }\mu F\]                                          

    B)  \[7.5\text{ }\mu F\]

    C)  \[22.5\mu F\]                  

    D)  \[30\text{ }\mu F\]

    Correct Answer: D

    Solution :

    Capacity of air capacitor \[C=\frac{A{{\varepsilon }_{0}}}{d}\] On placing a metallic plate of thickness t.                 \[C'=\frac{A{{\varepsilon }_{0}}}{d-t}\]                 \[\frac{C'}{C}=\frac{d}{d-t}\]                 \[\frac{C'}{15}=\frac{6}{6-3}\]                 \[C'=30\mu F\]


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