# Engineering Operational Amplifier Circuit

#### dwn

1. Homework Statement
See Image

2. Homework Equations

Source Transformations

3. The Attempt at a Solution

The answer is given, but I do not understand how they got it. When I multiply 9mA and 947.308Ω resistor, I get 8.526...what am I doing wrong? Also, could someone explain how they went on to get the final voltage in the simplified circuit. Don't you just add voltages when they are in series like this...?

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#### gneill

Mentor
8.526 V + 5.4 V = 13.926 V. So what's the problem?

#### dwn

According to their calculation they got .947 V

#### dwn

What does the Rf represent as well?

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#### AlephZero

Homework Helper
9 x 0.947 = 0.947 is obviously wrong, and looks like a typo.
It should be 9 x 0.947 = 8.523.

#### dwn

I haven't built up a lot of confidence with circuit analysis, so I wanted to make sure that it was in fact an error on there part. Thanks guys.

#### gneill

Mentor
According to their calculation they got .947 V
For what? We need some context here.

What does the Rf represent as well?
Rf is the resistance in the op-amp feedback path.

#### AlephZero

Homework Helper
What does the Rf represent as well?
The feedback resistor. 150k + 0.740k in series.

#### dwn

For what? We need some context here.

This is an online homework site and the guided solution provided a step-by-step solution, which is pictured in the first image I attached. AlphaZero already answered my question.

Thank you for the help.

"Operational Amplifier Circuit"

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