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NEET 2022 (Phase 1) · Charge Sharing & Loss of Energy

Charge Sharing & Loss of Energy question from NEET 2022 (Phase 1)

Q18NEET 2022 · PHASE 1Easy

Charge Sharing & Loss of Energy

A capacitor of capacitance C = 900 pF is charged fully by 100 V battery B as shown in figure (a). Then it is disconnected from the battery and connected to another uncharged capacitor of capacitance C = 900 pF as shown in figure (b). The electrostatic energy stored by the system (b) is

Figure

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Answer: (c)

  1. Charge Q=CV=900×10−12×100=9×10−8Q = CV = 900 \times 10^{-12} \times 100 = 9 \times 10^{-8} C.
  2. Shared equally between two equal capacitors: common V′=50V' = 50 V.
  3. U=12(2C)V′2=12×1800×10−12×2500=2.25×10−6U = \frac{1}{2}(2C)V'^2 = \frac{1}{2} \times 1800 \times 10^{-12} \times 2500 = 2.25 \times 10^{-6} J
  4. So the answer is (c) 2.25×10−62.25 \times 10^{-6} J.
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