*Question G9A06:
In what units is RF feed line loss usually expressed?*  

*Correct Answer is  D: Decibels per 100 feet*  

### AI Response: (may contain errors)  

RF feed line loss is typically expressed in decibels (dB) because this unit allows for a logarithmic representation of power loss over a distance. 

### Correct Answer: B: Decibels per 1,000 feet

- **Why this is correct**: 
  - Decibels provide a convenient way to express the ratio of power levels, making it easier to understand the loss over long distances. The loss is often specified per 100 feet or 1,000 feet, but decibels are the standard unit for measuring this type of loss in RF systems.

### Why the other choices are incorrect:

- **A: Ohms per 1,000 feet**: 
  - Ohms measure resistance, not loss. While resistance can affect signal quality, it does not directly quantify the loss of signal power over a distance.

- **C: Ohms per 100 feet**: 
  - Similar to choice A, this option uses ohms, which is not appropriate for measuring RF feed line loss. It does not provide a measure of power loss.

- **D: Decibels per 100 feet**: 
  - While this option is close, the standard expression for RF feed line loss is typically given per 1,000 feet. However, both 100 feet and 1,000 feet can be used, but the more common practice is to express it per 1,000 feet.

### Useful Formulas or Rules of Thumb:

- To convert loss from decibels per 100 feet to decibels per 1,000 feet, you can multiply by 10:
  
  $$ \text{Loss (dB per 1,000 feet)} = \text{Loss (dB per 100 feet)} \times 10 $$

This conversion is useful for understanding how feed line loss scales with distance.