ELECTROMAGNETIC
WA V E S
AND THE
ELECTROMAGNETIC
S P E C T R U M
WAVES are simply disturbances in a
particular physical medium or a field,
resulting in a vibration or oscillation.
Anatomy of a WAVE
1
3
Crest
Amplitude
Wavelength
4
2
Trough
• FREQUENCY
The number of crests that pass a given
point within
one second is described
as the frequency of the wave. One
wave— or cycle—per second is called a
Hertz (Hz), named after
Heinrich Hertz
• WAVELENGTH
The distance between crests/troughs is
the wavelength.
Longitudinal Wave
 particles of the medium move in a
direction parallel to the direction that the
wave moves.
Transverse Wave
 particles of the medium move in a
direction perpendicular to the direction
that the wave moves.
Mechanical Wave
 not capable of transmitting its
energy through a vacuum.
Electromagnetic Wave
 capable of transmitting its energy
through a vacuum (empty space)
ELECTROMAGNETIC WAVE
• produced and
propagated by the
vibration of charged
particles
• Oscillating charged
particle, creates
oscillating electric
and magnetic fields.
• Transverse Wave
• Can travel in a
vacuum
ELECTROMAGNETIC WAVE
• wavelength and frequency are inversely
proportional: the shorter the wavelength, the
higher the frequency, and vice versa.
c=λf
• Speed of EM wave in a vaccum:
c= 𝟑𝒙𝟏𝟎𝟖 m/s
• all electromagnetic radiation, regardless of
wavelength or frequency, travels at the speed
of light.
Example Problem:
A particular wave of electromagnetic
radiation has a frequency of 1.5𝑥1014 Hz
What is the wavelength of this wave?
2.00𝑥10−6 m
Example Problem:
What is the frequency of light waves with
a wavelength of 5𝑥10−7 m
Answer:
6𝑥1014 Hz
Example Problem:
Calculate for the wavelength.
Frequency =2.5𝑥1012 Hz
Answer:
1.2𝑥10−4 m
Example Problem:
Calculate for the frequency.
Wavelength = 350 nm
Answer:
8.57𝑥1014 m
ELECTROMAGNETIC SPECTRUM
• range of electromagnetic waves
when placed in order of increasing
frequency(left to right)
ELECTROMAGNETIC SPECTRUM
• Divided into different regions
• They all have different wavelengths
and different frequencies.
 Long wavelength - lowest frequency
 Short wavelength - highest frequency
 The higher the frequency, the higher
the energy.
RADIOWAVES
• longest wavelengths
(10−1 m to 104 m)
• lowest frequencies
(30kHz to 3000MHz)
• Used to transmit sound
and picture information
over long distances
A radio wave is generated
by a transmitter and then
detected by a receiver. An
antenna allows a radio
transmitter to send energy
and a receiver to pick up
energy. Transmitters and
receivers are typically
designed to operate over a
limited range of
frequencies.
Common Applications of Radiowaves
• Global Positioning
Systems (GPS)
measure the time it
takes a radio wave to
travel from several
satellites to the
receiver,
determining the
distance to each
satellite.
Common Applications of Radiowaves
• A radio picks up
radio waves through
an antenna and
converts it to sound
waves.
• Each radio station in
an area broadcasts at
a different frequency.
MICROWAVES
• wavelength ranges
from10−1 m to 10−3 m)
• Frequency ranges from
300MHz – 300GHz
• considered as highfrequency radio waves
• Can penetrate through
Earth’s atmosphere
Common Applications of Microwaves
• RADAR (Radio Detection and
Ranging) is a detection system
that uses radio waves to
determine the range, angle, or
velocity of objects. Sends out
radio waves and measuring
the time it takes them to
return.
Common Applications of Microwaves
• Microwave ovens use
electromagnetic waves at a
frequency of 2.45 GHz
(wavelength about 12 cm) that
make water molecules vibrate
fast and heat up.
• Bounces off at metal surfaces.
Common Applications of Microwaves
• Satellite Communication
– the use of artificial
satellites to provide
communication links
between various points on
Earth. Satellite
communications play a
vital role in the global
telecommunications
system.
INFRARED WAVES
• Means “below red”
• Wavelength ranges
from 7.5 x 10−7 m to
10−3 m)
• Frequency ranges from
3x1011 Hzto 4x1014 Hz
• Emitted by all objects
in the form of heat
Common Applications of Infrared
• TV remote controls
that rely on infrared
radiation shoot out
pulses of IR energy
from a light-emitting
diode (LED) to an IR
receiver in the TV.
• Thermal imaging is a
method of improving
visibility of objects in a
dark environment by
detecting the objects'
infrared radiation and
creating an image based
on that information.
VISIBLE LIGHT
• Shorter wavelength
(4x10−7 m to 8x10−7 m
and higher frequency
(4x1014 Hz to8x1014 Hz)
than infrared rays.
• Electromagnetic waves
we can see.
• Longest wavelength=
red light
• Shortest wavelength=
violet light
Ultraviolet Radiation
• Wavelength ranges from
6x10−10 m to 4x10−7 Hz)
• Frequency ranges from
8x1014 Hz to 8x1017 Hz
• Has three kinds: UVA,
UVB and UVC
Common Applications of UV Light
Common Applications of UV Light
• Ultraviolet germicidal
irradiation (UVGI) is
a disinfection method that
uses shortwavelength ultraviolet (U
V-C) light to kill or
inactivate microorganisms
by disrupting their DNA,
leaving them unable to
perform vital cellular
functions.
X-rays
• Wavelength ranges from
10−12 m to 10−8 Hz)
• Frequency ranges from
1017 Hz to 1020 Hz
• Produced when
accelerated electrons hit
a metal and some medical
equipment
• Can be classified as soft
or hard x-rays
Common Applications of UV Light
Gamma Rays
• Wavelength ranges from
10−14 m to 10−10 m)
• Frequency ranges from
1020 to 1024 Hz
• Given off by radioactive
materials like cobalt-60
and cesium-137
• Gamma-rays can kill
living cells and damage
tissues