2. • The electromagnetic spectrum is a
continuum of electromagnetic
waves arranged according to
frequency and wavelength.
• It is a gradual progression from the
waves of lowest frequencies to the
waves of highest frequencies.
3. • According to increasing frequency,
the EM spectrum includes: radio
waves, microwaves, infrared, visible
light, ultraviolet, X-rays, and gamma
rays.
• These waves do not have exact
dividing region.
4. • The different types of
electromagnetic waves are defined
by the amount of energy carried
by/possessed by the photons.
• Photons are bundles of wave
energy.
5. • From among the EM waves, the
gamma rays have photons of high
energies while radio waves have
photons with the lowest energies.
• With regard the wavelength, radio
waves can be likened to the size of a
football field while gamma rays are as
small as the nuclei of an atom.
6. RADIO WAVES
• Radio waves have the longest
wavelength in the electromagnetic
spectrum.
• They are produced by making
electrons vibrate in an antenna.
• They are used to transmit sound and
picture information over long distances.
7. • Radio waves have a very wide range of
wavelengths.
• The whole region of the radio waves is
divided into smaller regions or
wavebands.
• Each waveband is allocated by law to a
specific radio service.
8. • Low frequency waves are suitable for
communication over great distances.
• But the curvature of the earth limits the
range to about 80 kilometers.
• To extend the range, a repeater is
used.
• The repeater receives the signal and
re-transmits it to the receiving station.
9. • High frequency waves can be
reflected by the ionosphere.
• This enables the waves to be
transmitted over great
distances.
10. • Medium and high frequency waves are
used for broadcasting by local radio
stations.
• High frequency radio waves called
radio-frequency (RF) is used in
standard broadcasting because it can
be sent over long distances.
11. • Very high frequency waves
provides a higher quality
broadcasting including stereo
sound.
