# Using Thevenin's Theorem to work out the voltage across a load

Joined Sep 24, 2019
2
I have been given a question for homework and I think you have to use Thevenin's Theorem to answer it but I'm just not sure what to do. Maybe there is also a way of working it out without Thevenin's. I've only just learnt the theorem recently so I'm not very confident with it.

Here is the question:
In Figures (a) & (b), find Vab. [Answers: 4.2V; 7.2V]

#### ericgibbs

Joined Jan 29, 2010
11,667
hi John.
Welcome to AAC,
E

#### WBahn

Joined Mar 31, 2012
26,398
That's as far as I got (see attachment)
You're starting off on the wrong foot because you are throwing an equation at a problem when it doesn't apply.

You are using the current division formula for two resistors in parallel; the problem is that the two resistors aren't in parallel.

You certainly don't HAVE to use Thevenin's Theorem to solve these problems. The issue is whether you are required to because of the instructions on the assignment. If it's not required, then just analyze them like any other problem, perhaps using nodal analysis or mesh current analysis.

#### RBR1317

Joined Nov 13, 2010
597
I think you have to use Thevenin's Theorem to answer it
The given circuit has the appearance of a Norton equivalent connected to a Thevenin equivalent. What if you did a direct conversion of the Norton to a Thevenin form and then analyzed that?