Question

• A. 2 V
• B. -2 V
• C. 8 V
• D. -5 V

Hint:

For inverting op-amps, output is given by \(V_o = -\left(\dfrac{R_f}{R_{\text{in}}}\right)V_{\text{in}}\). Always watch the sign!

Answer 1

The Correct Option is B

This is a classic inverting amplifier configuration.
Step 1: Identify input voltage and resistors:
\(V_{\text{in}} = +0.4\ \text{V}\)
\(R_{\text{in}} = 20\ \text{k}\Omega\)
\(R_f = 100\ \text{k}\Omega\)
Step 2: Use the inverting amplifier formula: \[ V_o = -\left(\dfrac{R_f}{R_{\text{in}}}\right) \cdot V_{\text{in}} = -\left(\dfrac{100k}{20k}\right) \cdot 0.4 = -5 \cdot 0.4 = -2\ \text{V} \] The negative sign indicates phase reversal (inversion), characteristic of inverting amplifier circuits.