*Question G9B12:
What is the approximate length for a 1/4 wave monopole antenna cut for 28.5 MHz?*  

*Correct Answer is  A: 8 feet*  

### AI Response: (may contain errors)  

To determine the approximate length of a 1/4 wave monopole antenna for a frequency of 28.5 MHz, we can use the following formula:

$$
L = \frac{234}{f}
$$

where:
- $L$ = length of the antenna in feet
- $f$ = frequency in MHz

### Calculation:
For a frequency of 28.5 MHz:

$$
L = \frac{234}{28.5} \approx 8.21 \text{ feet}
$$

Rounding this to the nearest whole number gives us approximately 8 feet.

### Explanation of the Correct Answer:
- **Correct Answer: 8 feet**  
  This is the closest approximation to the calculated length of 8.21 feet for a 1/4 wave monopole antenna at 28.5 MHz.

### Explanation of Incorrect Choices:
- **B: 11 feet**  
  This length is too long for a 1/4 wave antenna at this frequency. It would correspond to a lower frequency.

- **C: 16 feet**  
  This length is significantly longer than needed for 28.5 MHz and would correspond to an even lower frequency.

- **D: 21 feet**  
  This is the longest option and is also too long for a 1/4 wave antenna at 28.5 MHz, indicating a much lower frequency.

### Summary:
- The formula $L = \frac{234}{f}$ is a useful rule of thumb for calculating the length of a 1/4 wave monopole antenna.
- For 28.5 MHz, the calculated length is approximately 8 feet, making it the correct choice.