What term describes the space occupied by one complete cycle of a radio wave at any given moment?

• A. Wavelength
• B. Amplitude
• C. Frequency
• D. Phase

Answer: (A)

The term is wavelength. Wavelength is the spatial length of one complete cycle of a wave, so it’s the distance from one point in the cycle to the identical point in the next cycle (for example, from one crest to the next crest). This describes how much space a single cycle occupies as the wave propagates. It’s related to frequency by the equation λ = v / f, where v is the wave’s speed and f its frequency; in air or vacuum, v is close to the speed of light, so higher frequency means a shorter wavelength. Amplitude describes how tall the wave is (its strength), not how far one cycle extends, and phase describes where in the cycle you are at a given point, not the length of the cycle. For a 100 MHz wave in vacuum, the wavelength would be about 3 meters.