# RL Circuit with current source

• Engineering

Image

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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NascentOxygen
Staff Emeritus
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).

NascentOxygen
Staff Emeritus
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)

NascentOxygen
Staff Emeritus
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.

NascentOxygen
Staff Emeritus
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.

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Guessing is not advisable. Don't you have some way to work it out?
The bread crumbs are not helping.