In a wave, the number of wave cycles that pass a given point in a given time.

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

Answer: (C)

Frequency is how many complete wave cycles pass a given point each second. It tells you how fast the wave oscillates at that point. If one cycle crosses the point every second, the frequency is 1 hertz. The term itself describes the rate of repetition, which is why it fits the description perfectly. Wavelength is the distance between identical points on successive cycles, not how often they pass by. Amplitude describes how tall or strong the wave is, not its repetition rate. Hertz is the unit used to measure frequency (cycles per second), but the concept being asked for is the frequency itself.