# Solving a Thevenin equivalent circuit

Suppose $R_{1}$ and $R_{2}$ are replaced by resistors of unknown values which are different from those assumed in part (a).

Using a variable external voltage source, a student applies $+1.5V$ between terminals a and b (a is positive relative to b) and measures a current $i_{0}$ of $-0.1A$. When the external voltage is $+3V$, the external voltage source generates power and $i_{0}$ is $+0.2A$.

Recalculate the Thevenin voltage and resistance in this case, assuming all sources are ideal.

I am not sure how to approach this.

• Use mesh analysis ( loop currents) or nodal analysis to find R1 and R2 and proceed in usual fashion. – Plutonium smuggler Nov 26 '14 at 0:12
• @Plutoniumsmuggler, I don't think that's the desired approach here. It will work, of course, but there is a far simpler method that Olin and I have in mind and, further, is the most likely object of this exercise. – Alfred Centauri Nov 26 '14 at 1:54
• @AlfredCentauri . I think you mean we already assume a Thevenin circuit and a voltage source in place of Load resistance ; then solve 2 equations for two unknowns . Right ? – Plutonium smuggler Nov 26 '14 at 11:20