Question
What is the typical input impedance of an op-amp?
Answer Options
- A) 100 ohms
- B) 10,000 ohms
- C) Very low
- D) Very high
Correct Answer: D
Explanation
An operational amplifier (\text{op-amp}) is a differential amplifier designed to be controlled primarily by voltage, drawing minimal current from the source. This characteristic is critical for minimizing the loading effect on the source circuit being monitored or amplified.
For an ideal \text{op-amp}, the input impedance is considered infinite. In practical terms, the typical input impedance of an \text{op-amp} (especially FET-input types) is very high (ranging from hundreds of kilohms to gigohms). This high input impedance ensures that the \text{op-amp} draws negligible current from the source, thereby preserving the signal’s integrity.
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