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A 10 μF capacitor is charged to a potential difference of 50 V and is connected to another uncharged capacitor in parallel. Now the common potential difference becomes 20 V . The capacitance of second capacitor is

Options

  1. A15 μF
  2. B30   μF
  3. C20   μF
  4. D10   μF

Correct answer

A. 15 μF

Step-by-step solution

q 1 = 10 × 50 = 500   μC ,   C 1 = 10   μF ,   C 2 = ? ,   q 2 = 0 As, V = q 1 + q 2 C 1 + C 2 C 1 + C 2 = q 1 + q 2 V = 500 + 0 20 = 25   μF C 2 = 25 - C 1 = 25 - 10 = 15   μF

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