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raface
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Homework Statement
Find the voltage drop across the capacitor just after the switch is opened v(0+)
Most variables are in picture attached
C = 100mF
Homework Equations
Vc(t)= Vc([tex]\infty[/tex])+[Vc(t+)-Vc([tex]\infty[/tex]))*e-(t-t1/[tex]\tau[/tex])
The Attempt at a Solution
First i assumed that the capacitor would be charge in steady state before the switch is opened. This would mean it is a short circuit. So the voltage in the capacitor would be 12V? Not sure if this is correct.
Secondly i assumed that as t tends to infinity, after the switch is opened that the voltage across the capacitor will become 30V
I then worked put the thevenin resistance of the capacitor circuit after the switch is opened.
RTh = 9.6154 ohms
Then
[tex]\tau[/tex] = RTh * C
I am not sure how to apply this to the first order equation to find v(0+)