# Finding Thevenin voltage using mesh analysis

#### jshrimp

Joined Nov 2, 2019
5

Using nodal analysis, Vth = 0. This is the answer provided in the solutions booklet.
Using mesh analysis, however, doesn't provide the same result?
What am I doing wrong?

#### Dodgydave

Joined Jun 22, 2012
11,233
Looking at the circuit, I would say Va is 10V, and Vb is 2.5V, so the difference is 7.5V...

#### jshrimp

Joined Nov 2, 2019
5
Looking at the circuit, I would say Va is 10V, and Vb is 2.5V, so the difference is 7.5V...
Ah, my bad, please disregard the first circuit. The current source on the right should be 2A not 0.5A.
Also, I would like to find Vth specifically using mesh analysis. Using nodal analysis, I am able to get Vth=0V. Using mesh analysis, I am not. I was just wondering if someone could point out my mistake.

#### Jony130

Joined Feb 17, 2009
5,484
How can I2 = -2A if we clearly have an open circuit in loop2?

#### jshrimp

Joined Nov 2, 2019
5
How can I2 = -2A if we clearly have an open circuit in loop2?
Thanks. Totally overlooked that. I understand now.

#### Dodgydave

Joined Jun 22, 2012
11,233
Then Va is 10V and Vb is 0V, if it's an open circuit.

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#### WBahn

Joined Mar 31, 2012
29,823
Then Vb is 10V and Va is 0V, if it's an open circuit.
How is Va equal to 0 V? You have a 2 A current source and, because of the open circuit, all 2 A must flow down through the 5 Ω resistor. Sure seems like that would make Va equal to 10 V.