*Question E6A07:
Which of the following indicates that a silicon NPN junction transistor is biased on?*  

*Correct Answer is  D: Base-to-emitter voltage of approximately 0.6 volts to 0.7 volts*  

### AI Response: (may contain errors)  

To determine if a silicon NPN junction transistor is biased on, we need to look at the base-to-emitter voltage (V_BE). 

1. **Correct Answer Explanation**:  
   - The correct answer is **D: Base-to-emitter voltage of approximately 0.6 volts to 0.7 volts**.  
   - For a silicon NPN transistor to be in the "on" state (forward-biased), the base-to-emitter voltage must typically be around $0.6 \, \text{V}$ to $0.7 \, \text{V}$. This voltage allows current to flow from the base to the emitter, enabling the transistor to conduct.

2. **Incorrect Choices Explanation**:  
   - **A: Base-to-emitter resistance of approximately 6 ohms to 7 ohms**:  
     - This value does not indicate biasing. Resistance values are not used to determine if a transistor is on; rather, we look at voltage levels.
   - **B: Base-to-emitter resistance of approximately 0.6 ohms to 0.7 ohms**:  
     - Similar to choice A, this resistance value does not provide information about the biasing state of the transistor. It is not a typical measurement for biasing.
   - **C: Base-to-emitter voltage of approximately 6 volts to 7 volts**:  
     - This voltage is too high for a silicon NPN transistor. A base-to-emitter voltage in this range would likely damage the transistor rather than bias it on.

3. **Useful Rules of Thumb**:  
   - For silicon transistors, the typical base-to-emitter voltage (V_BE) when conducting is around $0.6 \, \text{V}$ to $0.7 \, \text{V}$.
   - If V_BE is below this range, the transistor is likely off; if it exceeds this range significantly, it may be damaged.

In summary, the key to identifying if a silicon NPN transistor is biased on is to check for a base-to-emitter voltage of approximately $0.6 \, \text{V}$ to $0.7 \, \text{V}$.