The switch S shown in figure is kept closed for a long time and then opened at t = 0, then the current in the middle 20 Ω resistor at t = 0.25 ms is :

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The switch S shown in figure is kept closed for a long time and then opened at t = 0, then the current in the middle 20 &#937; resistor at t = 0.25 ms is :

Accepted Answer

Switch is kept closed for a long time,
Current through 20Ω resistor i =
q₀ = 25 × × 20 = 150 μC
at t = 0 , switch is opened, i = i₀e^−t/t
                            t = 0 i = i₀ e^−t/t
                            t = RC = 20 × 25 = 500 μS
Current
i = e^-1/2 = 0.189 A

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