Laplace transform of the given circuit

[Lucky Pradana]

Homework Statement

Find i2(t) from given circuit

Relevant Equations

Laplace transform of R-L circuit

Hello i have an assignment. From given circuit i need to find s domain and inverse them back to t domain.
can you help me by explain this circuit?

 

[anorlunda]

Show us your work. We are here to help with hints or to correct if you did it wrong. We can't do that unless we see your attempt at the solution first.

 

[Lucky Pradana]

im sorry,but i really have no idea. i really don't know what to do.
please show me some hints first and i will try it and post it here

 

[anorlunda]

Our guidelines say this.

Finally, we want you to develop the learning skills you need to succeed in all of your classes. You have to be able to get past the "I have no clue" phase on your own.

So if you were assigned this as homework, then the instructor thinks that you should be ready to solve it. What have you studied in this course about Laplace transforms? Did the lectures show how to analyze a circuit using Laplace properties?

 

[Lucky Pradana]

okay,understandable.
what do you think? where i miss?

 

[berkeman]

what do you think? where i miss?

Please learn to type your work into the forum window. That makes it *much* easier to read and for us to quote it. There is a tutorial at the top of the page under INFO, Help.

You can also see how LaTeX cleans up the posting of math equations in this similar thread:

https://www.physicsforums.com/threads/rc-time-constants-in-filters.987377/post-6327362

 

[cnh1995]

It is hard to follow your writing.
As Berkeman suggested, try to type your work here.
If you insist on using pen and paper, re-draw the circuit, label the components and write the equations clearly, step by step.

Solution approach:
First, convert all the circuit components into their respective Laplace domain equivalents. Then you can go ahead with a circuit analysis method that you find convenient (node voltage method, mesh analysis, Thevenin/Norton etc).

 

[Lucky Pradana]

from mesh analysis,is this formula corect?

Equation 1:
I1 RE + (I1-I2) R2 - Vs = 0
I1 (R1+R2) - I2 R2 = Vs
4 = I1 (R1+R2) - I2 R2
4 = I1 (10+R2) - I2 R2
I1 = (4 + 10 I2)/40

Equation 2:
-I1 R2 + I2 (R2+R3) + Ldi2/dt = 0

put equation 1 to 2
-10 I1 + I2 (10+20) + 0,1 di2/dt=0
-((4 + 10 I2)/40) + 30 I2 + 0,1 Si2(s) - S i (0)=0
-4 - 10 I2/40 + 30 I2 + 0,1 S i2(s) = 0
-0,1 - 0,25 I2 + 30 I2 + 0,1 I2(s) = 0
-0,1 + 29,75 I2 + 0,1 I2 (s) = 0
- 0,1 + I2 (29,75 + 0,1 (s)) = 0
I2 = 0,1 / 29,75 + 0,1 (s)
I2 = 0,1/s / 29,75/s + 0,1 (s)