Another question on transient

[I_need_help_thanks]

View attachment 63038

when t<=0, v(t)=100

do i need to calculate the impedance of the circuit when t<0? if yes, how can i do so?

thanks!

 

[ljcox]

It is 10 Ohm in parallel with 2 Farad.

 

[Ratchit]

I_need_help_thanks,

when t<=0, v(t)=100

do i need to calculate the impedance of the circuit when t<0? if yes, how can i do so?

Impedance has nothing to do with your problem. This time I set up and solved the equation with LaPlace transforms.

Ratch

View attachment 63043

 

[I_need_help_thanks]

thanks for your worked solution.

hi, is there an alternative solution to this problem which does not require the knowledge of laplace transformation?

 

[MrAl]

Hi,

Part of the solution will involve finding the response of the capacitor to the current source of 5 amps with the appropriate resistor value in parallel when the source of 100 volts is shorted out. So see if you can first calculate the voltage response of a capacitor in parallel with a resistor driven by a parallel current source. So you have three things in parallel: A resistor, a current source, and a capacitor. If you can find the response to this (perhaps use Thevenin and/or Norton) you're well on your way to solving this problem in the manner in which you desire. This solution involves superposition too.

 

[Ratchit]

INYHT,

hi, is there an alternative solution to this problem which does not require the knowledge of laplace transformation? .

Sure, you can do by the "cookbook" method using universal energizing/de-energizing curves, or write a simple first order differential equation and easily solve it. I illustrate the second method in the image attachment.

Ratch

View attachment 63078

 

[ljcox]

I used both Norton & Thevenin to solve it.