Create a free frequency wave diagram using tools like EdrawMax, as it has predefined symbols and icons that let you create factually correct wave diagrams. As the below image suggests, frequency describes the number of waves that pass a fixed place in a given amount of time. So if the time it takes for a wave to pass is ½ second, the frequency is 2 per second. To understand frequency wave diagrams, one should understand that frequency is the rate at which current changes direction per second. It is measured in hertz (Hz), an international unit of measure where 1 Hertz equals 1 cycle per second.