Let’s look at the electromagnetic spectrum. Why? Why not?!
Looking at each band of the electromagnetic spectrum, we will first focus on radio waves. Radio waves possess the longest wavelength and lowest frequency. Radio waves are typically used for communications, broadcasting, and radar systems.
Radio waves are propagated primarily by reflection and refraction in the planet’s ionosphere. Microwaves are most commonly encountered in heating units for cooking food. They are also used in telecommunications. Military radar systems also primarily operate in the microwave spectrum. Infrared radiation is of a higher frequency but shorter wavelength compared to microwaves. Thermal radiation is radiated via the infrared spectrum. Some communication systems also use the infrared spectrum. Visible spectrum light is that which produces the sense of color. Different surfaces reflect different wavelengths of electromagnetic radiation. Ultraviolet radiation is not visible to the human eye but can affect it. UV light is emitted by the sun and can produce sunburns or eye damage. It is also emitted by welding. High energy UV light is the longest wavelength EM radiation ionizing in nature.
Ionizing radiation can cause an electron to be ejected from an atom to generate an ion. This will cause free radical formation, which will result in chemical alteration of the material. In humans, the most damaging effect of this is the conversion of water in cell membranes to hydroxyl and hydronium, which changes the pH of the cell and can cause cellular death. Also, DNA strands can be compromised by chemical change of a portion of the helix causing cancerous cell daughters to be produced. The three types of ionizing electromagnetic radiation are X-rays, gamma rays, and cosmic rays. The nuclear decay of radioactive particles most commonly produces X-rays and gamma rays. Cosmic rays are energetic low-mass particles and electrons that shower the earth from outer space. These ionizing forms of electromagnetic radiation have very low wavelengths but carry relatively large amounts of energy.