Roughly one electron volt of energy is required to break a covalent bond from a molecule to produce one ion pair, and this is referred to as a nonthermal effect. Electromagnetic radiation above 2500 × 106 MHz is mostly referred to as ionizing radiation. The ionizing radiation source could be an electron beam, x-rays (machine generated), or gamma rays (from Cobalt-60 or Cesium-137), and the energy of a gamma ray is above 2 × 10−14 J. If the wavelength of radiation increases, the frequency and the energy of radiation decrease. Thus, nonionizing radiation energy is not capable of breaking all the chemical bonds. Microwaves belong to the group of nonionizing forms of radiation. Thus, they do not have sufficient energy (2 × 10−24 – 2 × 10−22 J) to affect all chemical bonds. Therefore, the nonionizing radiation is the electromagnetic radiation that does not carry enough energy or quanta to ionize atoms or molecules, represented mainly by ultraviolet rays (UV-A, UV-B, and UV-C), visible light, microwaves, and infrared.