A capacitor having capacitance ‘C’ is charged by a battery having e.m.f. 2V (Battery is disconnected after charging) . Now this charged capacitor is connected to another battery having e.m.f. V. The p

Question

A capacitor having capacitance ‘C’ is charged by a battery having e.m.f. 2V (Battery is disconnected after charging) . Now this charged capacitor is connected to another battery having e.m.f. V. The positive plate of capacitor is connected with –ve terminal of battery & vice-versa. The amount of heat produced after

connecting it with battery.

TestHub · Accepted Answer

1. Initial charge on capacitor: Q i ​ = C ( 2 V ) = 2 C V . Initial energy: U i ​ = 2 1 ​ C ( 2 V ) 2 = 2 C V 2 . 2. Final charge on capacitor (reversed polarity): Q f ​ = C ( − V ) = − C V . Final energy: U f ​ = 2 1 ​ C ( − V ) 2 = 2 1 ​ C V 2 . 3. Work done by battery: W ba tt ​ = V Δ Q = V ( Q f ​ − Q i ​ ) = V ( − C V − 2 C V ) = − 3 C V 2 . 4. Heat produced: H = U i ​ − U f ​ − W ba tt ​ = 2 C V 2 − 2 1 ​ C V 2 − ( − 3 C V 2 ) = 1.5 C V 2 + 3 C V 2 = 4.5 C V 2 . The final answer is 4.5 C V 2 ​ .

Physics - Capacitor Question with Solution | TestHub

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