*Question E6C11:
In Figure E6-3, which is the schematic symbol for the NOT operation (inversion)?*  

*Correct Answer is  C: 5*  

### AI Response: (may contain errors)  

In digital logic, the NOT operation, also known as inversion, is represented by a specific schematic symbol. The NOT gate takes a single input and inverts it, meaning it outputs the opposite value: if the input is 1, the output is 0, and vice versa.

### Explanation:

1. **Correct Answer: C (5)**
   - The schematic symbol for the NOT operation is a triangle pointing to the right with a small circle (often called a "bubble") at the output. This bubble indicates inversion. In Figure E6-3, symbol 5 matches this description, making it the correct choice for the NOT operation.

2. **Why the Other Choices are Incorrect:**
   - **Choice A (2):** This symbol typically represents an AND gate, which has multiple inputs and outputs a 1 only if all inputs are 1. It does not have the inversion bubble.
   - **Choice B (4):** This symbol is usually for an OR gate, which outputs a 1 if at least one input is 1. Like the AND gate, it lacks the inversion bubble.
   - **Choice D (6):** This symbol is often used for a NAND gate, which is an AND gate followed by a NOT gate. It has the inversion bubble, but it also has multiple inputs, distinguishing it from a simple NOT gate.

### Key Points:
- **NOT Gate Symbol:** Triangle with a bubble at the output.
- **Function:** Inverts the input signal.
- **Other Gates:** AND, OR, and NAND have different symbols and functions, often involving multiple inputs and different logic operations.

Understanding these symbols is crucial for interpreting and designing digital circuits, which is a key part of the FCC exam.