A capacitor is charged by a battery. The battery is removed and another identical uncharged capacitor is…

A capacitor is charged by a battery. The battery is removed and another identical uncharged capacitor is connected in parallel. The total electrostatic energy of resulting system
  1. increases by a factor of 4.
  2. decreases by a factor of 2.
  3. remains the same.
  4. increases by a factor of 2.

Solution


Charge on capacitor,
q=CV
When it is connected with another uncharged capacitor.

Vc=q1+q2C1+C2=q+0C+C
Vc=V2
Initial energy,
Ui=12CV2
Final energy,
Uf=12CV22+12CV22
=CV24
Loss of energy =Ui-Uf
=CV24,
i.e., decreases by a factor of 2.

Asked in: NEET 2017

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