7
DEFINITION OF
'ELECTROMAGNETIC
WAVES'
Definition: Electromagnetic waves or EM waves are waves
that
are created as a result of vibrations between an electric
fieId
and a magnetic field. In other words, EM waves are composed of oscillating magnetic and electric fieids. ¡
Description:
Electromagnetic waves are formed when an electric
fieId
comes in contact
with
a magnetic field. They are henee
known as 'electromagnetic' waves. The electric fieid and magnetic field of an electromagnetic wave are perpendicular (at right
angles)
to each other.
I
They are aiso perpendicular to the direction of the EM wave. i
EM waves travel
with
a constant velocity of 3.00 x 108 ms-1 in vacuum. They are deflected neither by the electric field, ñor by
the magnetic field. However, they are capable of showing Interference ordiffraction. An electromagnetic wave can travel through
anything - be it air, a solid material or vacuum. It does not need a médium to propágate or travel
from
one place to another.
Mechanical waves (like sound waves or water
waves),
on the other hand, need a médium to travel. EM waves are 'transverse'
waves.
This means
that
they are measured by their amplitude (height) and wavelength (distance between the highest/lowest
points of two consecutivo waves).
The highest point of a wave is known as 'crest', whereas the lowest point is known as 'trough', Electromagnetic waves can be
spiit into a range of frequencies. This is known as the electromagnetic spectrum. Examples of EM waves are radio waves,
microwaves,
infrared waves, X-rays, gamma
rays,
etc.
