The Red-belly snake (Storeria occipitomaculata) is a relatively small snake that rarely exceeds 12 inches in length. It is native to North America, Mexico and Central America, and it is NOT venomous.
The electromagnetic frequency of a wave is defined as how many times the peak of this oscillation moves past a point each second. This has a major effect on the properties of the wave, including its energy.
As most electromagnetic fields encountered in everyday situation are those generated by household or industrial appliances, the majority of EMF meters available are calibrated to measure 50 and 60 Hz alternating fields (the frequency of US and European mains electricity).