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RL Circuit with current source

  • Engineering
  • Thread starter dwn
  • Start date
  • #1
dwn
165
2

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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  • #2
NascentOxygen
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Up until t=0, what is the equation for current through R2?

How does the circuit change at t=0?
 
  • #3
dwn
165
2
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).
 
  • #4
NascentOxygen
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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?
 
  • #5
dwn
165
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Oh no I'm sorry, it should be 2* ((Rtotal/R1))
Rtotal = (R1*R2)/(R1 + R2)

Ie-Rt/L (R equivalent)
 
  • #6
NascentOxygen
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Oh no I'm sorry, it should be 2* ((Rtotal/R1))
Rtotal = (R1*R2)/(R1 + R2)
Which resistor carries that current?
 
  • #7
dwn
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R2, if I'm not mistaken.
 
  • #8
NascentOxygen
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R2, if I'm not mistaken.
Guessing is not advisable. Don't you have some way to work it out?
 
  • #9
dwn
165
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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
dwn
165
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Guessing is not advisable. Don't you have some way to work it out?
The bread crumbs are not helping.
 

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