Learning Goal: To analyze an RC circuit to determine the initial voltage across a capacitor, then to find the step response of the capacitor voltage, and finally to find other circuit quantities, such as current, voltage, power, or energy. The step response of an RC circuit is the response of the capacitor voltage to a sudden application of a DC source. When the switching occurs, the capacitor stores or releases energy.(Figure 1) Part A – If the switch in the circuit has been in position a for a long time, find the initial voltage across the capacitor at t = 0- Vs = 9.0V , Is = 79.0mA , R1 = 47.0k? , R2 = 91.0k? , R3 = 97.0k? , R4 = 45.0k? , R5 = 18.0k? , R6 = 11.0k? (kilo ohm) , C = 50.0?F (microF) . Express your answer to three significant figures and include the appropriate units. Part B – Find the time constant, ?, after t = 0 Vs = 39.0V , Is = 62.0mA , R1 = 65.0k? , R2 = 55.0k? , R3 = 60.0k? , R4 = 82.0k? , R5 = 16.0k? , R6 = 99.0k? (kilo ohm), C = 54.0?F (micro F). Express your answer to three significant figures and include the appropriate units. Part C – Find the Norton equivalent current seen by the capacitor after t = 0 Vs = 85.0V , R3 = 43.0k? , R4 = 76.0k? , R5 = 43.0k? , R6 = 42.0k? ( kilo ohm) , C = 48.0?F(micro F) . Express your answer to three significant figures and include the appropriate units. v(0?)=v(0+)= = Part D – Write an expression for the capacitor voltage, v(t), for t ? 0 Express your answer as an algebraic expression in terms of Vs, Is, R3, R5, R6, C.Part E – Write an expression for the power dissipated in the resistor R 6 for t ? 0+ (t > = 0+)Express your answer as an algebraic expression in terms of Vs, Is, R3, R5, R6, and C.

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