Introduction
In this chapter, we will study regarding displacement
current, electromagnetic waves and its various parts and their
uses. Electromagnetic waves in the form of visible light enable us
to view the world around us. Infrared waves warm our
environment. Radio waves carry our favorite TV and radio programs
and the list goes on and on.
History of EMW
Maxwell: was the first to predict the presence of
electromagnetic waves.
Hertz: produced and detected electromagnetic waves of
wavelength 6 m experimentally.
J.C. Bose: the produced electromagnetic wave of wavelength
ranging from 5 mm to 25 mm.
Marconi: successfully transmitted the EM waves up to a few
kilometers. Marconi discovered that if one of the spark gap
terminals is connected to an antenna and the other terminal is
earthed, the EM waves radiated could go up to several
kilometers.
Electromagnetic Waves
, Electromagnetic waves or EM waves are waves that are created
as a result of vibrations between an electric field and a magnetic
field. In other words, EM waves are composed of oscillating
magnetic and electric fields.
(i). Sources of electromagnetic waves
1. An electric charge at rest produces only an electrostatic field
around it.
2. A charge moving with uniform velocity produces both electric
and magnetic fields, here magnetic field does not change with
time hence it does not produce a time-varying electric field.
3. An accelerating charge produces both an electric field and
magnetic field which varies with space and time and forms
electromagnetic waves.
4. An accelerating charge emits an electromagnetic wave of the
same frequency as the frequency of an accelerating charge.
5. An electron orbiting around its nucleus in a stationary orbit
does not emit an electromagnetic wave. It will emit only during
the transition from higher energy orbit to lower energy orbit.
In this chapter, we will study regarding displacement
current, electromagnetic waves and its various parts and their
uses. Electromagnetic waves in the form of visible light enable us
to view the world around us. Infrared waves warm our
environment. Radio waves carry our favorite TV and radio programs
and the list goes on and on.
History of EMW
Maxwell: was the first to predict the presence of
electromagnetic waves.
Hertz: produced and detected electromagnetic waves of
wavelength 6 m experimentally.
J.C. Bose: the produced electromagnetic wave of wavelength
ranging from 5 mm to 25 mm.
Marconi: successfully transmitted the EM waves up to a few
kilometers. Marconi discovered that if one of the spark gap
terminals is connected to an antenna and the other terminal is
earthed, the EM waves radiated could go up to several
kilometers.
Electromagnetic Waves
, Electromagnetic waves or EM waves are waves that are created
as a result of vibrations between an electric field and a magnetic
field. In other words, EM waves are composed of oscillating
magnetic and electric fields.
(i). Sources of electromagnetic waves
1. An electric charge at rest produces only an electrostatic field
around it.
2. A charge moving with uniform velocity produces both electric
and magnetic fields, here magnetic field does not change with
time hence it does not produce a time-varying electric field.
3. An accelerating charge produces both an electric field and
magnetic field which varies with space and time and forms
electromagnetic waves.
4. An accelerating charge emits an electromagnetic wave of the
same frequency as the frequency of an accelerating charge.
5. An electron orbiting around its nucleus in a stationary orbit
does not emit an electromagnetic wave. It will emit only during
the transition from higher energy orbit to lower energy orbit.
