ARRL Technician Practice Exam 2025 - Free Technician License Practice Questions and Study Guide

The formula for converting frequency to approximate wavelength in meters is derived from the relationship between the speed of electromagnetic waves and the frequency and wavelength of those waves. The speed of light is approximately 300,000,000 meters per second (or 300 million meters per second), which is commonly rounded to 300 when working with megahertz (MHz).

When using the formula in option C, you divide 300 by the frequency measured in megahertz. This results in the wavelength in meters, allowing for an easy calculation using commonly encountered frequencies in amateur radio. For example, if you have a frequency of 3 MHz, using this formula, the wavelength can be calculated as 300 divided by 3, which equals 100 meters.

This approach is particularly useful for radio operators as it allows them to quickly determine the wavelength associated with a given frequency they may be operating at or planning to use. The other options either incorrectly multiply the frequency or use incorrect units that would not yield the desired result in meters.