What is Frequency?

Radio signals travel in waves, like the waves of the ocean. The rate at which the waves arrive in a fixed amount of time is called the frequency of the wave. For example, if 60 waves wash ashore in an hour, the frequency of the waves would be 60 waves per hour, or 1 wave per minute (as you know, there are 60 minutes in an hour).

Radio waves are not measured in waves per hour, but rather in waves per second. The frequency of radio waves is measured in units called “Hertz” after the famous scientist – Heinrich Rudolf Hertz - who studied radio waves in the 19 th century . One Hertz means that there is one radio wave per second. The frequency of radio waves is very fast, so generally radio waves are measured in “kilohertz” (kHz) – that is, 1000 waves per second – or “megahertz” (MHz) – which is 1,000,000 waves per second. Sometimes, radio waves are measured in “gigahertz” (GHz) – that is, 1,000,000,000 waves per second – or even greater units!

The important thing to remember is that radios are generally designed to listen to radio signals of particular frequency. When you listen to FM radio (the “F” in “FM” stands for frequency!) and tune to station 88.5, what you are doing is tuning to a radio signal with a frequency of 88,500,000 waves per second (or 88.5 MHz).