Radio waves are a type of electromagnetic radiation. A radio wave has a much longer wavelength than does visible light. We use radio wave,s extensively for communications.
Radio waves have wavelengths as short as a few millimeters (tenths of inches) and as long as hundreds of kilometers (hundreds of miles). Visible light, for comparison, has wavelengths in the 400 to 700 nanometer range, about 5,000 times shorter than the shortest wavelength radio wave,s. Radio wave,s oscillate at frequencies between a few kilohertz (kHz or thousands of hertz) and a few terahertz (THz or 1012 hertz). “Far infrared” radiation borders radio wave,s on the electromagnetic spectrum; far IR is slightly higher energy and shorter wavelength radiation than radio.
Microwaves, which we use for cooking and for communication, are short wavelength radio waves with wavelengths between a few and a few hundred millimeters (tenths of inches to tens of inches).
Various frequencies of radio wave,s are used for television and FM and AM radio broadcasts, military communications, mobile phones, ham radio, wireless computer networks, and numerous other communications applications.
Most radio waves pass freely through Earth’s atmosphere. However, some frequencies can be reflected or absorbed by the charged particles in the ionosphere.