InterviewSolution
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InterviewSolution
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Calculate the potential difference and the energy stored in the capacitor C_2 in the circuit shown in the Fig. Given potential at A is 90 V , C_1 = 20 mu F , C_2 = 30 mu Fand C_3 = 15 mu F |
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Answer» Solution :Let as SHOWN in Fig `V_1 , V_2` and `V_3` be the respective potential differences across the capacitors `C_1 , C_2` and `C_3` respectively . In series combination same charge Q exists on each capacitor and `V_1 : V_2 : V_3 = (1)/(C_(1)) : (1)/(C_(2)) : (1)/(C_(3))` `implies V_(1)= (C_(2))/(C_(1)) V_(2) = (30)/(20) V_(2)` and `V_(3) = (C_(2))/(C_(3)) V_(2) = (30)/(15) V_(2)` But `V_(1) + V_(2) + V_(3) = 90 V` , hence we have `(30)/(20) V_(2) + V_(2) + (30)/(15) V_(2) = 90 V implies 45 V_(2) = 90 V implies V_(2) = 20 V `  Moreover , energy stored in capacitor `C_2` is `V_2 = (1)/(2) C_(2) V_(2)^(2) = (1)/(2) xx (30 mu F) xx (20 V)^(2) = 6000 mu J = 6.0 mJ` |
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