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The plates of a parallel plate capacitor are charged to a potential difference of 117 V and then connected across a resistor. The potential difference across the capacitor decreases exponentially with respect to time. After 1 s the potential difference between the plates is 39 V , then after 2 s from the start, the potential difference ( in V ) between the plates is

Correct answer

13

Step-by-step solution

During discharging V C =V e - t / R C t = 1 , V 1 = V e - 1 / RC = V 3 ∴ e - 1 / R C = 1 3 … … 1 after 2 s , V 2 = Ve - 2 / RC = V 1 3 2 = 117 9 = 13

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