Frequency

You have probably heard the term 60-cycle voltage used in reference to ordinary household current in the United States (or 50 cycle voltage in Europe and Asia).

What do you suppose this term means?

Remember that ac current flow can be represented by sine waves. The period of time required for the current to advance from zero, through the maximum value, then back to zero is called an alternation.

The period of time required for the current to advance from zero to a maximum in one direction, decay to zero, then build to a maximum in the other direction, and finally return to zero is called a cycle.

The term 60-cycles means that the electricity must go through a complete cycle 60 times each second. The number of cycles occurring in each second, or frequency, is measured in units called Hertz, after Gustav Hertz, a German physicist. Hertz is abbreviated as Hz.