How is frequency defined in the context of sine waves?

Frequency in the context of sine waves refers to the number of cycles that occur in one second. This measure is crucial in understanding wave phenomena, such as sound and electromagnetic waves, as it directly relates to how often the wave oscillates. When we say a wave has a frequency measured in hertz (Hz), we are indicating that the wave completes a specific number of complete oscillations or cycles every second. Thus, in this context, the correct definition of frequency as "cycles per second" provides a clear understanding of how waves behave over time, emphasizing the temporal aspect of the wave's repetition. Other concepts, like energy or velocity, relate to different properties of wave behavior but do not define frequency itself.