Exam-style question
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In an inverting amplifier, if the calculated output voltage is -18 V but the supply rails are ±12 V, what will the output be?.
- A.-18 V
- B.-12 V
- C.0 V
- D.+12 V
Model answer
What a good answer should say
- -12 V
Explanation
Why this works
Initial state: Supply rails V+ = +12 V, V− = -12 V. Calculated output Vout_calc = -18 V.
Step 1: Check if Vout_calc < V−. Step 2: Since -18 V < -12 V, output is clamped to negative rail.
Final state: Vout_actual = -12 V. Conclusion: Output cannot go below negative supply rail, so -12 V is observed.
Common mistake
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