The property of electromagnetic waves measured in Hertz is frequency.

Here's a breakdown:

* Frequency refers to the number of wave cycles that pass a given point in one second.

* Hertz (Hz) is the unit of measurement for frequency. One Hertz represents one cycle per second.

So, when we say a radio wave has a frequency of 100 MHz (megahertz), it means that 100 million wave cycles pass a point every second.