1.4 - Radio Waves
Radio waves and the electromagnetic spectrum
- Radio waves are part of the electromagnetic (EM) spectrum.
- They have the longest wavelengths and the lowest frequencies of all EM waves.
- Like all EM waves, they are transverse and travel at the speed of light through a vacuum.
- Their long wavelengths make them useful for carrying signals over long distances, such as radio and television broadcasts.
Radio waves carry communication signals
- Radio waves are used mainly for communication - they carry television and radio broadcasts from one place to another.
- Radio waves have wavelengths longer than about 10 cm, and how a radio wave travels from transmitter to receiver depends on its wavelength.
- Longer-wavelength radio waves can be received over very large distances.
- The very short wavelengths used for TV and FM radio only reach a receiver in line of sight of the transmitter, because they don't bend or travel far through obstacles.
