Solve Laplace Transform Homework: Find i(t) for t>0

[ranju]

Homework Statement

we have to solve the given circuit using laplace transform for i(t) for t>0 when switch k opened at t=0..
now all I wnated to make clear is the final circuit diagram of this in s-domain..[/B]

Homework Equations

The Attempt at a Solution

as I solved I considered the circuit to be in steady state before switch is opened so , current across inductor is 6A...[/B]

 

[lazyaditya]

Images are not clear.

 

[lazyaditya]

What is i(0+) you are getting ?

 

[ranju]

well only the left hand portion is'nt clear.. in 1st pic.. there is 12V voltage source & in 2nd pic it is 12/s in s-domain..
i(0+)=i(0-) = 6A..

 

[lazyaditya]

can you show your working for i(0-).

 

[ranju]

sorry actually I did a calculation mistake..i(0-) =4 A.. and I found the equivalent current of the circuit considering it in steady state before switch is opened.. so the inductor is dhorted so the whole 4 A current pass across the inductor branch..!

 

[lazyaditya]

Are you sure the current will be 4 A,mine is coming 14 A.

 

[ranju]

you are right .. ..

 

[lazyaditya]

Your second image is correct.

 

[ranju]

thanks and additional thanks for correcting that mistake.. :p

 

[lazyaditya]

You are welcome.