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The frequency of an AC signal tells you how many full cycles of an AC waveform are generated in 1 second. It is expressed as a number of cycles per second or as a number of hertz (20 hertz, 1000 hertz, 20,000 hertz...). Standard AC mains voltage (generated in the USA) is 60 cycles per second which can be expressed as 60 hertz..
Wavelength = 1,126.8/f
The speed of sound at sea level at 20°C. It can be changed if you wish.
The previous diagram showed two sine waves. These were 2 pure tones overlaid on one another. If the 2 tones were mixed together and viewed with an oscilloscope, they would look like the following diagram. In this case the two waves are 100hz and 400hz. The two highest peaks correspond to the peaks of the 100hz sine wave. As you can see, the peaks are 0.01 seconds apart (as we will calculate a little later).
Time vs Frequency:
t = 1/f
Frequency vs Time:
f = 1/t
This next link is a large file (160k+) and will take a few minutes to download. Please be patient.
This is a multi-tone .wav file. There are 6 different frequencies. They are 40hz, 100hz, 250hz, 500hz, 1000hz and 2000hz. Each lasts for 3 seconds. Be careful with the volume. The first tone is a very low frequency which your speakers may not be able to reproduce. If you turn the volume too loud at first, you may damage your speakers or get a really loud surprise when the next frequency starts.
The following is a sample of pink noise on the same scale as the multi-tone wave (100hz & 400hz). You can see that it is much more complex than the sample with only 2 tones.