*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. 

1. **Correct Answer (Choice C: 5)**:
   - The symbol for the NOT operation is a triangle pointing to the right with a small circle at the output. This indicates that the output is the inverse of the input. In Figure E6-3, choice 5 corresponds to this standard representation.

2. **Incorrect Choices**:
   - **Choice A: 2**: This symbol typically represents an AND gate, which outputs a high signal only when all inputs are high. It does not perform inversion.
   - **Choice B: 4**: This symbol usually represents an OR gate, which outputs a high signal when at least one input is high. Again, this does not perform inversion.
   - **Choice D: 6**: This symbol is often used for a NAND gate, which outputs a low signal only when all inputs are high. It is a combination of AND followed by NOT, but it is not the direct representation of the NOT operation.

3. **Useful Rules of Thumb**:
   - Remember that the NOT gate is a fundamental building block in digital electronics, and its symbol is universally recognized as a triangle with a circle.
   - Familiarize yourself with the symbols for basic logic gates (AND, OR, NOT, NAND, NOR, XOR) as they are commonly tested in the Extra Class exam.

By understanding these symbols and their functions, you can confidently identify the NOT operation in schematic diagrams.