**2. What is electromagnetic energy?**

Electromagnetic (EM) energy travels in waves and spans a very broad wavelength spectrum from DC voltage, to very short wavelengths in gamma radiation (**Figure 1**).

RF energy is small part of electromagnetic spectrum having frequencies in the range of Kilohertz to Gigahertz. The shorter wavelength and the higher frequency, the more energetic are quanta of EM radiation and the more destructive it can be for the tissue. RF energy, Microwaves, Infrared and Visible Light has relatively low frequencies and represent non-ionizing radiation which is not able to modify the DNA (genes) inside the cells. High frequency radiation as UV, X-ray and Gamma are ionizing radiation which in natural conditions is generated by plasma or by radiative isotopes.

A very small part of RF spectrum range is used in EBD, and its properties will be the primary focus of the current chapter.

**Figure 1.** *Electromagnetic Spectrum.*
