What does a radio wave frequency represent?

• A. The number of complete cycles per second.
• B. The speed of the wave.
• C. The amplitude of the wave.
• D. The distance traveled per cycle.

Answer: (A)

Frequency is the number of complete oscillations the wave makes each second. In a radio wave, the electric and magnetic fields rise and fall in a cycle, and counting how many of those cycles occur per second gives you the frequency, measured in hertz. This ties to how fast the wave can be in free space, since the speed of light is roughly constant and the wavelength is set by lambda = c/f. So a higher frequency means more cycles per second and a shorter wavelength, while the wave’s speed stays about the same in vacuum. The other properties describe different aspects: speed is how fast the wave travels, amplitude is how tall the wave is, and distance per cycle is the wavelength, not the cycle rate.