What is used to measure distance of a radio wavelength?

• A. Two adjacent points on the wave
• B. A single crest
• C. Frequency difference
• D. Phase angle

Answer: (A)

Wavelength is the distance the wave travels during one complete cycle. That distance is found by measuring between two points that are in the same phase of the wave, such as two adjacent crests (or two adjacent troughs). So the distance between two adjacent points on the wave represents one wavelength.

A single crest by itself doesn’t define a full cycle, so it doesn’t give a wavelength. Frequency difference relates to how often the wave cycles per second, not the length of one cycle. Phase angle describes where you are in the cycle at a point in space, not the actual distance of the cycle itself.