The frequency of oscillation is the measure of how often a wave peaks in a given time frame. Lots of phenomena occur in waves. Ripples on a pond, sound and other vibrations are mathematically described in terms of waves. A typical waveform has a peak and a valley -- also known as a crest and trough -- and repeats the peak-and-valley phenomenon over and over again at a regular interval. The wavelength is a measure of the distance from one peak to the next and is necessary for understanding and describing the frequency.
Determine the speed of travel of the waves in question. Light travels at 186,000 miles per second. Sound waves travel at approximately 1125.33 feet per second, but will vary depending on temperature.
Determine the wavelength of the waves in question. This is the measure from one peak to the next. You can determine the approximate wavelength of light based on its color. To determine the wavelength of sound waves, you may need an oscilloscope.
Calculate the frequency of oscillation by dividing the speed of travel by the wavelength.