Engineering Need help on solving a RL circuit with switch

AI Thread Summary
The discussion revolves around solving a RL circuit with a switch, focusing on finding the voltage v(t) for t < 0 and t > 0. The original poster struggles to reconcile their calculations for the inductor current with the textbook's answers, specifically noting discrepancies in the values for i(t) and v(t). Clarifications are sought regarding the behavior of the circuit at t=0, particularly the flow of current through different branches and the role of the controlled source. Participants emphasize the importance of understanding the circuit's configuration and the significance of notation, such as the 'o' symbol in current representation. Overall, the thread highlights common challenges in analyzing RL circuits and the need for clear communication of circuit behavior.
madcowdisease
Messages
2
Reaction score
0

Homework Statement


tLfeD.jpg



Homework Equations


Find v(t) for t < 0 and t > 0 in the circuit.


The Attempt at a Solution


I tried to find the i through the inductor for both t=0- and t=infinity, but I did not get the same result as the answer given in the txtbook which is 96e-4t V. According to the answer given from the txtbk, if I'm not wrong, i(t) shud be i(t)=48e-4t A, and then to find v at the 2 ohm resistor, i(t) X 2 and u get v(t).

I do not really understand why, I've been on this qn for 1 hr and stil can't understand it.
Please help and thank you.
 
Physics news on Phys.org
madcowdisease said:

Homework Statement


tLfeD.jpg



Homework Equations


Find v(t) for t < 0 and t > 0 in the circuit.


The Attempt at a Solution


I tried to find the i through the inductor for both t=0- and t=infinity, but I did not get the same result as the answer given in the txtbook which is 96e-4t V. According to the answer given from the txtbk, if I'm not wrong, i(t) shud be i(t)=48e-4t A, and then to find v at the 2 ohm resistor, i(t) X 2 and u get v(t).

I do not really understand why, I've been on this qn for 1 hr and stil can't understand it.
Please help and thank you.

What's I_o?
 
Io is I0, the value should be calculated when t=o-
 
madcowdisease said:
Io is I0, the value should be calculated when t=o-

It's a bit confusing for me, but to clarify... So the switch is opened at t=0? And right before then, there is 1*I_o flowing to the left, and 3*I_o flowing to the right? To add up to the 4*I_o that is supplied by the dependent current source in the middle?
 
I think the idea is that at t=0, the 3-ohm branch is disconnected and the 8-ohm branch is connected. The controlled source is a voltage source since it has the + and - signs in it, not an arrow.

I noticed there's a little o symbol right below the arrow for current i. Is that significant?
 

Similar threads

Replies
10
Views
2K
Replies
1
Views
929
Replies
2
Views
9K
Replies
13
Views
2K
Replies
7
Views
4K
Replies
2
Views
2K
Replies
2
Views
2K
Replies
1
Views
12K
Back
Top