One or more options correct
A battery of emf and negligible internal resistance is connected in series with a resistor and a parallel combination of a resistor and an initially uncharged capacitor . The circuit is closed at . Which of the following statements is/are correct?
- A. The battery current immediately after closing the circuit is .
- B. The final charge on the capacitor is .
- C. The time constant of the charging is .
- D. The final energy stored in the capacitor is .
Show answer and solution
Answer: A, B
At the uncharged capacitor behaves like a wire across , so mA, and (A) is true. In the steady state no current enters the capacitor; the current is mA and the capacitor voltage equals the drop across , V, so and (B) is true. The time constant uses the Thevenin resistance seen by the capacitor, , giving ms, not ms (C is false). Final energy is mJ, and mJ would correspond to the full V (D is false).
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