RAJASTHAN PMT Rajasthan - PMT Solved Paper-2010

  • question_answer
    The plates of parallel plate capacitor are charged upto 100V. A 2 mm thick plate is inserted between the plates. Then to maintain the same potential difference, the distance between the plates is increased by 1.6 mm. The dielectric constant of the plate is

    A)  5                                            

    B)  1.25

    C)  4                            

    D)         2.5

    Correct Answer: A

    Solution :

    In air the potential difference between the plates                 \[{{V}_{air}}=\frac{\sigma }{{{\varepsilon }_{0}}}\cdot d\]                                             ... (i) In the presence of partially filled medium potential difference between the plates                 \[{{V}_{m}}=\frac{\sigma }{{{\varepsilon }_{0}}}\left( d-t+\frac{t}{K} \right)\]                     ? (ii) Potential difference between the plates with dielectric medium and increased distance is                 \[{{V}_{m}}=\frac{\sigma }{{{\varepsilon }_{0}}}\left\{ (d+d)-t+\frac{t}{k} \right\}\]         ... (iii) According to question\[{{V}_{air}}={{V}_{m}}\]which gives                 \[K=\frac{t}{t-d}\] Hence,  \[K=\frac{2}{2-1.6}=5\]


You need to login to perform this action.
You will be redirected in 3 sec spinner