*Question T3B06:
What is the formula for converting frequency to approximate wavelength in meters?*  

*Correct Answer is  D: Wavelength in meters equals 300 divided by frequency in megahertz*  

### AI Response: (may contain errors)  

To convert frequency to approximate wavelength in meters, the correct formula is:

$$
\text{Wavelength (meters)} = \frac{300}{\text{Frequency (megahertz)}}
$$

### Explanation of the Correct Answer (Choice D):
- This formula is derived from the relationship between frequency and wavelength, where the speed of light ($c$) is approximately $300,000,000$ meters per second (or $300$ million meters per second).
- When you express frequency in megahertz (MHz), you can simplify the calculation by using the factor of $300$. Thus, for a frequency in MHz, the wavelength in meters can be calculated easily.

### Why the Other Choices are Incorrect:
- **Choice A: Wavelength in meters equals frequency in hertz multiplied by 300**
  - This is incorrect because it does not account for the correct relationship between frequency and wavelength. The correct relationship involves division, not multiplication.

- **Choice B: Wavelength in meters equals frequency in hertz divided by 300**
  - This is incorrect because it uses hertz instead of megahertz. The factor of $300$ is applicable when using megahertz, not hertz. The correct conversion would require a different factor.

- **Choice C: Wavelength in meters equals frequency in megahertz divided by 300**
  - This is incorrect because it also uses division incorrectly. The correct relationship is that wavelength is equal to $300$ divided by the frequency in megahertz, not the other way around.

### Useful Formulas and Rules of Thumb:
- The speed of light ($c$) is approximately $300,000,000$ m/s.
- The relationship between frequency ($f$) in hertz and wavelength ($\lambda$) in meters is given by:
  
$$
\lambda = \frac{c}{f}
$$

- For practical calculations in amateur radio, using megahertz simplifies the formula to:

$$
\lambda \approx \frac{300}{f \text{ (MHz)}}
$$

This formula allows you to quickly estimate the wavelength for any given frequency in megahertz, which is particularly useful for antenna design and tuning.