- #1

- 62

- 0

## Homework Statement

Consider the circuit drawn below

This diagram was the closest I could find online to the one equivalent to my question, but there are some adjustments I need to clarify.

1)Replace Rz, Rf, and Rin, to R1.

2)Also, in my question, there's an extra wire connecting Vout to the right of Rz. In this wire, there is a resistor in the middle, called R2.

3) Switch the + symbol to the negative side and the - symbol to the + side.

**Edit: Here I redrew it in paint to give a better illustration of the circuit:**

**Now for the question:**

A) In terms of Vin, Vout, R1, and R2, what is the voltage at the non-inverting input to the op-amp (v+)?

B) In terms of Vin, Vout, R1, and R2, what is the input current to the circuit ( the current through R1)?

c) In terms of Vin, R1, and R2, what is the output voltage (Vout) of the circuit.

## Homework Equations

Kirchoff's loop equations

V+ = V-

V= IR

## The Attempt at a Solution

I guess something I'm confused about in this question is if this is considered to be a non-inverting or inverting amplifer, since the wires go from both sides of Vout.

A)

So one of the main rules for op amps is that the voltage at the non inverting input will equal the voltage of the inverting input. This can be solved by using a voltage divider.

Therefore, at Voltage at the non inverting input, V+ = Vout(R1/(R1+R1)) = Vout/2

Also V+ = V- = Vin can be another way to express this. Therefore we also get the expression Vin = Vout/2

However, I'm not sure if this is correct, since the question wanted it in terms of 4 variables, while I only have it in terms of Vout.

B)

current = i = (V(-) - Vin)/R1 =[Vin-Vin]/R1

So the current cancels and becomes 0, which doesn't make sense. So something is wrong with part A.

I'm having trouble finding the voltage through the non inverting input for starters, so if anyone can help me through that it would be appreciated.

Last edited: