- radio waves
- microwaves
- infrared radiation
- visible light
- ultraviolet radiation
- X-rays
- gamma rays
radio waves : Radio waves have the lowest frequencies of all types of EMR, and its photons carry the least amount of energy. Usually, anything between 3kHz and 300 GHz is considered to be a radio wave, although some definitions class anything above 1 GHz or 3GHz as microwaves.
microwaves: Microwaves are electromagnetic radiation with frequencies between 300 MHz (wavelength 100 cm) and 300 GHz (0.1 cm). Apart from a bit more energetic photons and a shorter wavelength (which means more energy density), they’re kinda-radio-wave-ish really. In fact, microwaves are extensively used in communication as well, but with a few key differences from radio waves.
Infrared radiation :It comes just long of the visible spectrum, spanning from 300 GHz (1mm) to the lower visible limit (the color red) at 430 THz (700 nm).
Visible light :This is the interval of electromagnetic radiation that your eyes are tuned to pick up. Visible light spans the spectrum from 430-770 THz (390 to 700 nm). We see different colors
because certain bits of this spectrum get absorbed by objects, and the rest gets reflected.
Ultraviolet radiation :The EM spectrum over the frequency of 789 terahertz (THz) or more is called ultraviolet. Ultraviolet light is composed of really short waves, from 10 nm to 400 nm, and carry a lot of energy. In fact, starting from the UV border, photons carry enough energy to alter certain chemical bonds into new arrangements.
X-rays :X-rays (and the more energetic gamma rays) are made up of photons that all carry minimum-ionization energy (they can all photoionize), and are thus called ionizing radiation. They can inflict massive damage on organisms and biomolecules, often affecting tissues very deeply below the skin as they easily penetrate through most matter.
Gamma rays :They have frequencies in excess of 30 exahertz, and wavelengths of under 10 picometers (1 picometer is a thousandth of a nanometer or a thousandth of a billionth of a meter), which is less than the diameter of an atom.
