What is the term for the number of waves that pass a given point each second?

• A. Wavelength
• B. Frequency
• C. Quantum
• D. Electromagnetic radiation

Answer: (B)

Frequency is the number of waves that pass a given point each second. It tells you how often the wave cycles occur per unit time, and in waves we measure it in cycles per second, or hertz. Wavelength is a spatial property—the distance between successive crests—so it describes how long the wave is rather than how often it passes a point. Quantum refers to the smallest unit of energy a wave can carry, not its rate of passage. Electromagnetic radiation describes the type of wave, not how often it passes a point. For a quick link, the wave’s speed equals its frequency times its wavelength (v = fλ).