Engineering How to Approach an RL Circuit with a Current Source for Homework?

AI Thread Summary
The discussion focuses on solving an RL circuit with a current source, particularly analyzing the behavior before and after t=0. Participants express confusion about determining the current through R2 and the circuit's changes at t=0, noting that the inductor acts as a current source once the external source is removed. The current divider rule is mentioned, with emphasis on calculating the equivalent resistance and its impact on current flow. There is a consensus that guessing is not a reliable method for solving the problem, and participants encourage a more systematic approach to understanding the circuit dynamics. The conversation highlights the importance of understanding impedance and the exponential decay of current in the circuit.
dwn
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Homework Statement



Image


Homework Equations



Current divider

The Attempt at a Solution



The only thing I see is that I solve for R1 and R2 for t < 0. Other than that I'm confused and not even sure I'm right about solving t<0.
 

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Up until t=0, what is the equation for current through R2?

How does the circuit change at t=0?
 
Current Divider : 2 ( R1 + R2)/R1

The source is gone, stuck in the closed loop (essentially), and the inductor becomes the current source (the energy within the inductor decays exponentially).
 
dwn said:
Current Divider : 2 ( R1 + R2)/R1
That fraction is > 1.0 ?

The source is gone, stuck in the closed loop (essentially), and the inductor becomes the current source (the energy within the inductor decays exponentially).
So what is the general form of the equation describing this decay?
 
Oh no I'm sorry, it should be 2* ((Rtotal/R1))
Rtotal = (R1*R2)/(R1 + R2)

Ie-Rt/L (R equivalent)
 
dwn said:
Oh no I'm sorry, it should be 2* ((Rtotal/R1))
Rtotal = (R1*R2)/(R1 + R2)
Which resistor carries that current?
 
R2, if I'm not mistaken.
 
dwn said:
R2, if I'm not mistaken.
Guessing is not advisable. Don't you have some way to work it out?
 
Of course, the reason I put that was bc the forum requires min 4 characters...

We choose the "unwanted" resistor to divide from the total because it has something to do with impedance (never covered this topic in class). I know the larger the resistance the less current flowing through it.
 
Last edited:
  • #10
NascentOxygen said:
Guessing is not advisable. Don't you have some way to work it out?

The bread crumbs are not helping.
 

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