*Question E9F06:
What is the approximate physical length of an air-insulated, parallel conductor transmission line that is electrically 1/2 wavelength long at 14.10 MHz?*  

*Correct Answer is  C: 10.6 meters*  

### AI Response: (may contain errors)  

To determine the physical length of an air-insulated, parallel conductor transmission line that is electrically 1/2 wavelength long at 14.10 MHz, we can use the following formula to calculate the wavelength ($\lambda$):

$$
\lambda = \frac{c}{f}
$$

where:
- $c$ = speed of light in a vacuum (approximately $3 \times 10^8$ meters/second)
- $f$ = frequency in hertz (Hz)

1. **Calculate the wavelength at 14.10 MHz:**
   - Convert frequency to hertz: $14.10 \text{ MHz} = 14.10 \times 10^6 \text{ Hz}$
   - Now, substitute into the wavelength formula:

   $$
   \lambda = \frac{3 \times 10^8 \text{ m/s}}{14.10 \times 10^6 \text{ Hz}} \approx 21.3 \text{ meters}
   $$

2. **Determine the length of the transmission line:**
   - Since we need the length for 1/2 wavelength:

   $$
   L = \frac{\lambda}{2} = \frac{21.3 \text{ meters}}{2} \approx 10.65 \text{ meters}
   $$

   Rounding this gives us approximately **10.6 meters**, which is the correct answer.

### Why the Correct Answer is Correct:
- The calculation shows that the physical length of the transmission line that is electrically 1/2 wavelength long at 14.10 MHz is indeed approximately 10.6 meters.

### Why the Other Choices are Incorrect:
- **A: 7.0 meters**: This is too short; it would correspond to a 1/3 wavelength at this frequency.
- **B: 8.5 meters**: This is also too short; it does not correspond to any standard fraction of the wavelength at this frequency.
- **D: 13.3 meters**: This is too long; it would correspond to a length greater than 1/2 wavelength.

### Summary:
- The correct answer is **C: 10.6 meters** because it accurately represents the physical length of a transmission line that is 1/2 wavelength long at the specified frequency. The other options do not match the calculated wavelength fractions.