Exam-style question
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What role does the feedback resistor play in maintaining the output polarity in a non‑inverting amplifier?.
- A.It inverts the signal.
- B.It provides a reference for the inverting input.
- C.It sets the gain but does not affect polarity.
- D.It connects the output to the non‑inverting input.
Model answer
What a good answer should say
- It provides a reference for the inverting input.
Explanation
Why this works
Initial state: The feedback resistor connects the output to the − input. Step‑by‑step execution: 1.
The resistor forms part of a voltage divider that sets the voltage at the − input. 2.
As the output changes, the divider adjusts the − input voltage to match the + input. 3.
This keeps the difference between inputs near zero, ensuring the output follows the input polarity. Final state: The feedback resistor maintains the correct reference voltage at the − input.
Conclusion: The resistor’s role is to provide the reference that keeps the output polarity aligned with the input.
Common mistake
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