radio waves are used to broadcast tv and radio signals and to transmit satellite signals
long-waves radio (wavelength of 1 - 10km) can be transmitted from London and received halfway round the world.
that's because long wavelengths bend around the curved surface of the earth
the radio waves used for tv and fm radio transmissions have very short wavelengths (10cm - 10m).
to get reception, you must be in direct sight of the transmitter - the signal doesn't bend around hills or travel far through buildings
short-wave radio signals (wavelengths of about 10m - 100m) can, like long-wave be received at long distances from the transmitter.
that's because they are reflected from the ionosphere - an electrically charged layer in the earth's upper atmosphere.
medium wave signals can also reflect from the ionosphere, depending on atmospheric conditions and time of day
some very short-wave radio waves can pass though the ionosphere - so they can be used for satellite communications
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