- #1

james weaver

- 28

- 4

- Homework Statement
- find Io

- Relevant Equations
- ohms law

Hi, so my objective is to find Io, and I've attached a picture of my work. Here is my question: At the point Vo1, if I use the equation for finding the output voltage for a non-inverting op amp I end up getting this:

$$V_{0{1}}=\left( 1+\frac {r_{f}} {r_{1}} \right)V_{s1} = \left( 1+\frac {40k} {10k} \right)2 = 10v$$

However, I can calculate the current ##I_{3}## by using ohms law:

$$\frac{V_{s1}-V_{A}} {10k}=\frac {2v} {10k}=0.2mA$$

From there, I start at Vs1 and add the voltage drops until I reach Vo1, which gives me: ##2-50k*I_{3}=-8v##

My instinct is to go with the -8, since ##I_{3}## would have to be reversed if it were 10v. Can you please help explain to me which one is right and why? Thanks.

$$V_{0{1}}=\left( 1+\frac {r_{f}} {r_{1}} \right)V_{s1} = \left( 1+\frac {40k} {10k} \right)2 = 10v$$

However, I can calculate the current ##I_{3}## by using ohms law:

$$\frac{V_{s1}-V_{A}} {10k}=\frac {2v} {10k}=0.2mA$$

From there, I start at Vs1 and add the voltage drops until I reach Vo1, which gives me: ##2-50k*I_{3}=-8v##

My instinct is to go with the -8, since ##I_{3}## would have to be reversed if it were 10v. Can you please help explain to me which one is right and why? Thanks.