Math Problem Statement

Find the output voltage of the op-amp circuit given below, where Vs = 8 V.

Solution

This is an op-amp circuit problem. Let's analyze the circuit based on the given components.

Given Information:

  • Vs=8VV_s = 8 \, \text{V}
  • There's a 1V DC source at the non-inverting input (+) of the op-amp.
  • The feedback resistor is 2 kΩ connected between the output and the inverting input (-).
  • We are asked to find the output voltage VoV_o.

Assumptions:

  • Since there is a direct connection from the output to the inverting input through the resistor, this is a negative feedback configuration.
  • In an ideal op-amp with negative feedback, the voltage at the inverting input (-) is forced to equal the voltage at the non-inverting input (+). So, V=V+=1VV_{-} = V_{+} = 1 \, \text{V}.

Steps to Solve:

  1. Non-inverting input voltage: The voltage at the non-inverting input is given as 1 V.

  2. Inverting input voltage: Since this is a negative feedback op-amp, the inverting input voltage will also be 1 V.

  3. Voltage across the 2 kΩ resistor: The voltage across the resistor is the difference between the output voltage VoV_o and the voltage at the inverting input (1 V). Therefore: Vo1V=I2kΩV_o - 1 \, \text{V} = I \cdot 2 \, \text{k}\Omega where II is the current through the resistor.

  4. Current through the 2 kΩ resistor: The current II can be calculated from the source Vs=8VV_s = 8 \, \text{V} and the voltage at the inverting input (1 V): I=Vs1VR=8V1V2kΩ=72000A=3.5mAI = \frac{V_s - 1 \, \text{V}}{R} = \frac{8 \, \text{V} - 1 \, \text{V}}{2 \, \text{k}\Omega} = \frac{7}{2000} \, \text{A} = 3.5 \, \text{mA}

  5. Output voltage: Now, applying Ohm’s Law across the resistor, the voltage difference between the output and inverting input must be: Vo1=(3.5mA)×(2kΩ)=7VV_o - 1 = (3.5 \, \text{mA}) \times (2 \, \text{k}\Omega) = 7 \, \text{V} So, Vo=7V+1V=8VV_o = 7 \, \text{V} + 1 \, \text{V} = 8 \, \text{V}

Final Answer:

The output voltage VoV_o is 8 V.


Do you have any questions or would you like more details? Here are 5 related questions that could extend your understanding:

  1. What is the role of negative feedback in an op-amp?
  2. How would the output change if the feedback resistor value increased?
  3. What would happen if the non-inverting input voltage changed to 2 V?
  4. How would you calculate the output if the resistor was replaced with a 1 kΩ resistor?
  5. What is the difference between inverting and non-inverting op-amp configurations?

Tip: Always check the feedback loop in an op-amp circuit, as it dictates the behavior of the amplifier!

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Math Problem Analysis

Mathematical Concepts

Op-Amp Circuit Analysis
Ohm's Law
Negative Feedback
Ideal Op-Amp Behavior

Formulas

V_o - V_{in} = I * R
I = (V_s - V_{in}) / R

Theorems

Ohm's Law
Ideal Op-Amp Assumption

Suitable Grade Level

Grades 11-12, Early College