11. A radio wave is an
electromagnetic wave
propagated by an antenna.
Radio waves have different
frequencies. The listener
can tune the radio receiver
to a specific frequency to
catch a specific radio
signal. For example, all FM
radio stations transmit in a
band of frequencies
between 88 megahertz
(millions of cycles per
second) and 108 megahertz,
and any listener who tunes
his radio receiver to a
frequency falling in this
range would have access to
that specific FM radio
station's programs.
