Radiation can be broadly classified into two types.
Radiation can be broadly classified into two types: electromagnetic waves which like light, travel in wave form, and particle beams consisting of small particles flying at high speeds. Electromagnetic waves include a variety of waves, not just radiation. Electromagnetic waves with a wavelength of approximately 100 meters are called radio waves, and are used for radio broadcasts. The electromagnetic waves used in microwave ovens are called microwaves. These have a short wavelength of about 1 meter. At even shorter wavelengths, we have infrared waves, visible light waves, and ultraviolet waves. Beyond these, at even shorter wavelengths, we have high energy X-rays and gamma rays. These waves are characterized by their ability to pass through objects. The wavelength of X-rays is one one-hundred-millionth of a centimeter, and the wavelength of gamma rays is one billionth of a centimeter.