Final answer:
For complex waves, the pattern that repeats the slowest is the periodic wave and establishes the fundamental frequency. The period is the time for one cycle, and frequency measures the number of cycles per second.
Step-by-step explanation:
For complex waves, there is a periodic wave, which is the pattern that repeats the slowest. This will be the fundamental frequency for the whole complex wave, even though its other components have different frequencies.
Most waves appear complex because they result from two or more simple waves that combine, known as the principle of superposition. These simple harmonic waves, which can be modeled using sine and cosine functions, repeat for several cycles. Periodic waves, such as those in simple harmonic motion, repeat the same oscillation for several cycles, and this repetition can be quantified by its amplitude, frequency, wavelength, speed, and energy.
The period of a wave is the time that a wave takes to complete one cycle and is usually measured in seconds, while frequency is the number of waves passing a point per unit time, measured in hertz (Hz), where 1 Hz = 1 s-1.