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## Homework Statement

For some reason I don't use this theorem since Thevenin's theorem is more common. I'm asked to find the Norton equivalent source between the terminals ##A## and ##B## for the following:

## Homework Equations

## The Attempt at a Solution

The first step is to short ##R_2##, and to find the short circuit current across that wiring.

I believe KCL at the node above the ##3 mA## would be useful:

##\sum I = 0 \Rightarrow 3mA + I_{sc} - I_R = 0 \Rightarrow I_{sc} = I_R - 3mA = \frac{V_{Node} + 20V}{4k} - 3mA##

Now ##V_{Node}## is the voltage across the ##3 mA##. Applying KVL around the left loop using the current source as a constraint:

##\sum V = 0 \Rightarrow 20V + V_R + V_{Node} = 0 \Rightarrow V_{Node} = -(20V + V_R) = -(20V + (3mA)(4k)) = - 32V##

This implies that ##I_{sc} = \frac{-32V + 20V}{4k} - 3mA = - 6mA##.

Is this reasonable?