Two capacitors of capacitances C and 2 C are charged to potential differences V and 2 V , respectively.…

Two capacitors of capacitances C and 2C are charged to potential differences V and 2V, respectively. These are then connected in parallel in such a manner that the positive terminal of one is connected to the negative terminal of the other. The final energy of this configuration is :
  1. 256CV2
  2. 32CV2
  3. zero
  4. 92CV2

Solution

Charge on C=CV
Charge on 2C=2C2V

From charge conservation, 2C(2V)-CV=(C+2C)V'
Common potential, V'=V
Final energy, Uf=12CV2+12×2CV2=32CV2

Asked in: JEE Main 2020 (05 Sep Shift 1)

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