*Question E7G03:
What is the typical input impedance of an op-amp?*  

*Correct Answer is  D: Very high*  

### AI Response: (may contain errors)  

An operational amplifier (op-amp) is a key component in many electronic circuits, known for its high input impedance and low output impedance. Let's break down the question:

1. **Correct Answer: Very high (D)**  
   - **Explanation**: Op-amps are designed to have a very high input impedance, often in the range of megaohms (MΩ) or higher. This high input impedance is crucial because it allows the op-amp to draw minimal current from the input source, thus not loading down the circuit it is connected to. This characteristic is essential for accurate signal amplification without affecting the original signal.

2. **Why the Other Choices are Incorrect**:
   - **A: 100 ohms**  
     - This is a very low impedance value, typical of resistors or certain types of loads, not op-amps.
   - **B: 10,000 ohms**  
     - While 10,000 ohms (or 10 kΩ) is higher than 100 ohms, it is still not high enough to be considered typical for an op-amp's input impedance. Op-amps usually have input impedances much higher than this.
   - **C: Very low**  
     - This is the opposite of what is true for op-amps. A very low input impedance would mean the op-amp draws significant current from the input source, which is not desirable for most applications.

3. **Useful Rule of Thumb**:
   - **High Input Impedance**: Op-amps are designed to have input impedances that are typically greater than $1 \, \text{M}\Omega$. This ensures minimal interaction with the input signal source.

Understanding these characteristics of op-amps is crucial for designing circuits that require precise signal amplification and minimal signal distortion.