How to Determine the Frequency of the Wave From the Slope
- 1). Inspect the graph to determine what variable is plotted on the x-axis and y-axis. You could either have wavelength on the x-axis and speed on the y-axis or the exact opposite case.
- 2). Convert the units of the slope so that the distance units cancel. Achieve this conversion by making both distance units the same. This is done because frequency does not contain any distance units. For example, given a slope of 10 second times foot per inch you would multiply by 12 inches per foot to get 120 second times foot per inch times inch per foot. The inch and foot units cancel out leaving a slope of 120 seconds. Since a slope of unit seconds results, wavelength was plotted on the x-axis and speed was plotted on the y-axis.
- 3). Divide one by the slope, to get frequency in hertz, if speed was plotted on the x-axis and wavelength was plotted on the y-axis. (See References 3 and 4) If wavelength was plotted on the x-axis and speed was plotted on the y-axis, the slope equals the frequency in hertz. (See References 3 and 4) Continuing the example leads to 1 divided by 120 seconds, or a frequency of 0.0083 hertz.