 #1
 8
 1
 Homework Statement:

Determine v(t) for t > 0 in the circuit of Fig. 7.114 if
v(0) = 0
 Relevant Equations:
 v(t) = Vs + (Vo  Vs) e^(t/(RC))
Dear PF,
In the figure down below is Q7.47 which asks to determine the voltage v(t) across the capacitor for t > 0.
Since it is given that V(0) = 0 there are two scenario's which is between time interval 0 < t < 1 and t > 1 according to the independent sources.
For the scenario 0 < t < 1 the current source is off and the voltage source Vs is 24V. Filling in the formula gives us 2424e^(t) which agrees on the answer sheet.
However, for scenario 2 we need to find Vo just before t = 1. I do that by using the previous formula and that gives me approximately 15.17V.
However, I am not quite sure how to find Vs in the second scenario between I am not quite sure what is happening in the circuit. The capacitor will first act as a short circuit but looks to DC as an open circuit so will current flow through the 8 and 12 ohm resistor or only the 8 ohm resistor?
However, I cannot seem to find the second part of the answer in the book for the time interval t > 1
Could anyone clarify what is happening for t > 1?
In the figure down below is Q7.47 which asks to determine the voltage v(t) across the capacitor for t > 0.
Since it is given that V(0) = 0 there are two scenario's which is between time interval 0 < t < 1 and t > 1 according to the independent sources.
For the scenario 0 < t < 1 the current source is off and the voltage source Vs is 24V. Filling in the formula gives us 2424e^(t) which agrees on the answer sheet.
However, for scenario 2 we need to find Vo just before t = 1. I do that by using the previous formula and that gives me approximately 15.17V.
However, I am not quite sure how to find Vs in the second scenario between I am not quite sure what is happening in the circuit. The capacitor will first act as a short circuit but looks to DC as an open circuit so will current flow through the 8 and 12 ohm resistor or only the 8 ohm resistor?
However, I cannot seem to find the second part of the answer in the book for the time interval t > 1
Could anyone clarify what is happening for t > 1?