The GATE Grind

GATE 2026 EC – Question 17

Analog Circuits · Op-amp Circuits · 1 mark · Multiple choice

The ideal OP-AMP circuit shown in the Figure produces output voltage $V_o = x$ when the Switch, S, is open. Which of the options represents the output voltage when S is closed?

Diagram for GATE 2026 EC question 17
  1. $x$
  2. $\frac23 x$
  3. $\frac34 x$
  4. $\frac12 x$

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Show answer and explanation

Correct answer: (C) $\frac34 x$

Explanation

Open switch: gain $=1+(2+1)/1=4$, so $x=4$ V. Closed switch shorts the 1 kΩ in feedback: gain $=1+2/1=3$, so $V_o=3=\tfrac34x$.