JEE Main & Advanced Physics Alternating Current / प्रत्यावर्ती धारा Question Bank Self Evaluation Test - Alternating Current

  • question_answer
    The two capacitors, shown in the circuit, are initially uncharged and the cell is ideal. The switch S is closed at t=0. Which of the following functions represents the current i(t) through the cell as a function of time? Here\[{{i}_{0}},\,{{i}_{1}},\,{{i}_{2}}\]are constants.

    A) \[i(t)={{i}_{0}}+{{i}_{1}}{{e}^{-t/\tau }}\]; \[\tau =3C\times \frac{R}{3}\]

    B) \[i(t)={{i}_{0}}+{{i}_{1}}{{e}^{-t/\tau }}+{{i}_{2}}{{e}^{-t/2\tau }}\];  \[\tau =RC\]

    C) \[i(t)={{i}_{1}}+{{i}_{1}}{{e}^{-t/\tau }}\]; \[\tau =3C\times \frac{R}{3}\]

    D) \[i(t)={{i}_{0}}+{{i}_{1}}{{e}^{-t/\tau }}\];  \[\tau =3RC\]

    Correct Answer: B

    Solution :

    [b] The three branches of the circuits carry currents \[i={{i}_{0}}\], \[i={{i}_{1}}\,{{e}^{t/RC}}\] and \[i={{i}_{2}}\,2{{e}^{-t/2Rc}}\] respectively. The current through the cell, i(t) can be found by using Kirchhoff's current law (or mode law).


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