*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. Here's why:

1. **Correct Answer: Base-to-emitter voltage of approximately 0.6 volts to 0.7 volts (Choice D)**  
   - A silicon NPN transistor requires a base-to-emitter voltage ($V_{BE}$) of about 0.6 to 0.7 volts to be in the "on" state, allowing current to flow from the collector to the emitter. This voltage is necessary to overcome the potential barrier of the silicon material and allow the transistor to conduct.

2. **Why the other choices are incorrect:**
   - **Choice A: Base-to-emitter resistance of approximately 6 ohms to 7 ohms**  
     - Resistance is not a direct indicator of whether a transistor is biased on. The key parameter is the voltage across the base-emitter junction, not its resistance.
   
   - **Choice B: Base-to-emitter resistance of approximately 0.6 ohms to 0.7 ohms**  
     - Similar to Choice A, resistance is not the correct parameter to determine if the transistor is on. The resistance values given are not relevant to the biasing condition.
   
   - **Choice C: Base-to-emitter voltage of approximately 6 volts to 7 volts**  
     - This voltage is too high for a silicon NPN transistor. Such a high voltage would likely damage the transistor. The correct voltage range is much lower, around 0.6 to 0.7 volts.

3. **Useful Rule of Thumb:**
   - For silicon transistors, remember that the base-to-emitter voltage ($V_{BE}$) required to turn the transistor on is typically around 0.6 to 0.7 volts. This is a key parameter for biasing transistors in circuits.