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Electrostatic Potential And Capacitance

Question
CBSEENPH12047780

A capacitor having capacitance 1 uF with air, is filled with two dielectrics as shown. How many times capacitance will increase

              

  • 12

  • 6

  • 8/3

  • 3

Solution

B.

6

After filling with dielectrics the two capacitors will be in parallel order. As shown, the two capacitors are connected in parallel. Initially the capacitance of capacitor

                  

                              C = εoAd

 

where A is area of each plate and d is the separation between the plates.

After filling with dielectrics, we have two capacitors of capacitance.

                                C1 = K1εo A2dC2 = 82εoAdC2 = 4εoAdC2  = 4C

                        And  C2 = K2 εo A2d          C2 = 42εoAd           C2 = 2εod            C2 = 2 C

Hence, their equivalent capacitance
                               Ceq = C1 + C2 

                                    = 4C +2C 

                               C  = 6C

ie, new capacitance will be six times of the original.

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