PSpice Review

Given problem

Place a DC current source between terminals and sweep the current from 0 to 3 amps. We can find Vth=10V when I terminal = 0A. Rth is the slope which is equal to 10/3 =3.33 ohms.

Then, assume RL=R4=10 ohms. The Thevenin Equivalent circuit is shown as following

Norton Equivalent circuit is 

Set RL is from 1 to 10 as following

Then graph power (V6*V6)/RL vs RL, and then RL should be 3.33 ohms in order to get the maximum power which is 7.5 W.