Obtain the Thevenin equivalent circuit parameters Vth and Rth for the following network.
Obtain the Thevenin equivalent circuit parameters Vth and Rth for the following network.

Right Answer is:
Vth = 10V, Rth = 5 Ω
SOLUTION
Apply KCL in the loop
20 – 3I – 6I + 10 = 0
I = (20 + 10) / (3 + 6)
I = 30 / 9
V6Ω = (30 / 9) × 6
V6Ω = 20 V
Now apply KCL in the outer loop
– 10 + V6Ω – Vab = 0
Vab = Vth = (20 – 10) V = 10 V
where, I = current through loop
Calculation of Rth
Rth = [3 || 6] + 3
Rth = 2 + 3 = 5 Ω