Radio waves are a type of electromagnetic radiation with wavelengths
in the electromagnetic spectrum longer than infrared light. Radio
waves have frequencies as high as 300 gigahertz (GHz) to as low as 30
hertz (Hz). At 300 GHz, the corresponding wavelength is 1 mm (shorter
than a grain of rice); at 30 Hz the corresponding wavelength is 10,000
km (longer than the radius of the Earth). Like all other
electromagnetic waves, radio waves travel at the speed of light in
vacuum (and close to the speed of light in the Earth's atmosphere,
which acts as the transmission media for the vast majority of
terrestrial use). Radio waves are generated by charged particles
undergoing acceleration, such as time-varying electric currents.
Naturally occurring radio waves are emitted by lightning and
astronomical objects.Radio waves are generated artificially by
transmitters and received by radio receivers, using antennas. Radio
waves are very widely used in modern technology for fixed and mobile
radio communication, broadcasting, radar and radio navigation systems,
communications satellites, wireless computer networks and many other
applications. Different frequencies of radio waves have different
propagation characteristics in the Earth's atmosphere; long waves can
diffract around obstacles like mountains and follow the contour of the
earth (ground waves), shorter waves can reflect off the ionosphere and
return to earth beyond the horizon (skywaves), while much shorter
wavelengths bend or diffract very little and travel on a line of
sight, so their propagation distances are limited to the visual
horizon.To prevent interference between different users, the
artificial generation and use of radio waves is strictly regulated by
law, coordinated by an international body called the International
Telecommunications Union (ITU), which defines radio waves as
"electromagnetic waves of frequencies arbitrarily lower than 3 000
GHz, propagated in space without artificial guide". The radio spectrum
is divided into a number of radio bands on the basis of frequency,
allocated to different uses.Radio waves were first predicted by
mathematical work done in 1867 by Scottish mathematical physicist
James Clerk Maxwell. His mathematical theory, now called Maxwell's
equations, predicted that a coupled electric and magnetic field could
travel through space as an "electromagnetic wave". Maxwell proposed
that light consisted of electromagnetic waves of very short
wavelength. In 1887, German physicist Heinrich Hertz demonstrated the
reality of Maxwell's electromagnetic waves by experimentally
generating radio waves in his laboratory, showing that they exhibited
the same wave properties as light: standing waves, refraction,
diffraction, and polarization. Italian inventor Guglielmo Marconi
developed the first practical radio transmitters and receivers around
1894â€"1895. He received the 1909 Nobel Prize in physics for his radio
work. Radio communication began to be used commercially around 1900.
The modern term "radio wave" replaced the original name "Hertzian
wave" around 1912. Radio wave Biography, NetWorth, Height, Age, Weight, Family, Married, Son, Daughter