Need help on solving a RL circuit with switch

In summary: I'm not sure whether I'm looking at it the right way. The o symbol is significant. It indicates that the current is flowing in the opposite direction of the arrow.
  • #1
madcowdisease
2
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.
 
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  • #2
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?
 
  • #3
Io is I0, the value should be calculated when t=o-
 
  • #4
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?
 
  • #5
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?
 

Related to Need help on solving a RL circuit with switch

1. What is a RL circuit with a switch?

A RL circuit with a switch is a type of electrical circuit that consists of a resistor (R) and an inductor (L) connected in series, with a switch that can be opened or closed to control the flow of current. It is commonly used in electronic devices and systems to control the timing and intensity of electrical signals.

2. How do I solve a RL circuit with a switch?

To solve a RL circuit with a switch, you will need to use the principles of Kirchoff's laws and the equations for calculating the voltage and current in a RL circuit. Start by drawing the circuit diagram and labeling all the components. Then, use Kirchoff's voltage law to write an equation for the voltage across the entire circuit. Next, use Kirchoff's current law to write an equation for the current at any point in the circuit. Finally, use the equations for calculating voltage and current in a RL circuit to solve for the values at different points in the circuit.

3. What is the purpose of a switch in a RL circuit?

The purpose of a switch in a RL circuit is to control the flow of current. When the switch is open, the circuit is broken and no current can flow. When the switch is closed, the circuit is complete and current can flow through the circuit. This allows for the control of timing and intensity of electrical signals in the circuit.

4. What are some common applications of a RL circuit with a switch?

A RL circuit with a switch has a wide range of applications in electronic devices and systems. Some common applications include timing circuits, pulse generators, motor control circuits, and power supply circuits. It is also commonly used in electronic circuits for audio and radio frequency signals.

5. What are some tips for solving a RL circuit with a switch?

Here are some tips for solving a RL circuit with a switch:

  • Draw a clear and accurate circuit diagram.
  • Label all the components and their values.
  • Use Kirchoff's laws to write equations for voltage and current in the circuit.
  • Solve for the values at different points in the circuit using the appropriate equations for a RL circuit.
  • Double-check your calculations to ensure accuracy.
  • If possible, use a circuit simulator software to verify your results.

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