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JEE Advanced2019PhysicsAlternating CurrentActual

In the circuit shown, initially there is no charge on capacitors and keys S 1 and S 2 are open. The values of the capacitors are C 1 = 10 μ F , C 2 = 30 μ F and C 3 = C 4 = 80 μ F . Which of the statement(s) is/are correct?

Options

  1. AIf key S 1 is kept closed for long time such that capacitors are fully charged, the voltage difference between
  2. BThe keys S 1 is kept closed for long time such that capacitors are fully charged. Now key S 2 is closed, at th
  3. CAt time t = 0 , the key S 1 is closed, the instantaneous current in the closed circuit will be 25 m A .
  4. DIf key S 1 is kept closed for long time such that capacitors are fully charged, the voltage across the capacit

Correct answer

C. At time t = 0 , the key S 1 is closed, the instantaneous current in the closed circuit will be 25 m A .

Step-by-step solution

For option ( C ) , refer circuit diagram below Just after closing of switch charge on all the capacitors C 1 , C 3 a n d C 4 = 0 ∴ Replace all capacitors with wire, then circuit will get reduced as shown below. i = 5 70 + 100 + 30 = 5 200 = 25 m A ⇒ ( C ) is correct Now S 1 is kept closed for long time circuit is in steady state ⇒ Apply KVL in loop, start from battery + 5 - 2 80 - 2 10 - 2 80 = 0 ⇒ 10.2 80 = 5 ⇒ 2 = 40 μ C ⇒ Potential difference across C 1 Δ V C 1 = 2 10 = 40 10 = 4 v o l t ⇒ ( D ) is correct. For

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