This illustration describes the electromagnetic spectrum which is divided into non-ionizing and ionizing electromagnetic fields depending on the energy the radiation contains. The fields with the lowest energy are the extremely low frequency (ELF) fields to the left with 10-1 000 Hz, and a long wavelength of 10 000 km and more. These fields are typically arising from electric powerlines. Increasing the energy in the fields the next part in the spectrum is the radiofrequency electromagnetic fields. They are used for broadcasting, mobile phone technology and navigation such as radars and has frequencies ranging from 10 000 000 – 10 000 000 000 000 Hz and wavelengths from 1 km to 1 mm. These fields contain much higher energy than the ELF fields, but even higher energy are in the infrared, visual light and ultraviolet spectrum of the fields. Approximately when the electromagnetic waves are 10-7 m and has a frequency of 100 000 000 000 000 000 Hz the radiation waves themselves contain enough energy to ionize molecules. This part of the spectrum is called the ionizing electromagnetic fields and the fields are called X-rays which are used in medicine and GAMMA-rays which are known from radioactive sources.