The document provides an overview of electromagnetic (em) waves and the electromagnetic spectrum, detailing their properties, classifications, and various uses. It discusses wave types from radio waves to gamma rays, highlighting their frequencies, energy characteristics, and applications in communication, medical imaging, and treatment. The dangers of high-frequency em waves, particularly in relation to health risks, are also addressed.

1.  The spectrum is arranged from long to
short wavelength or from low to high
frequency.
 The speed of all EM waves is the same!

2.  Electromagnetic waves
are produced by rapidly
accelerated or decelerated
charged particles
 Consist of oscillating
electric and magnetic
fields that are at right
angles to each other
 They travels in vacuum of space in the form of sinusoidal waves
with the speed of light: 3.0x108m/s
 It contains properties of both electrical and magnetic waves.

3.  EM waves transport energy through empty space,
stored in propagating electric and magnetic fields.
 Magnetic field variation is perpendicular to magnetic
field.
 A single freq. electromagnetic wave exhibits a sinusoidal
variation of electric and magnetic fields in space.

5.  The energy carried by an
EM wave is determined by
The frequency of the wave
 E = h f
E = energy
h = constant known as
Planck’s constant
f = frequency
Dangerous EM waves have very high
frequencies and should be avoided

6.  The entire range of EM waves is known as the Electromagnetic
Spectrum.
 Radio waves
 Microwaves
 Infrared waves
 Visible light
▪ Red
▪ Orange
▪ Yellow
▪ Green
▪ Blue
▪ Indigo
▪ Violet
 Ultraviolet
 X-rays
 Gamma Rays

7.  Low frequency and longer
wavelength waves.
 Radio stations transmit
information into coded form.
RADIO
WAVES

9.  AM-amplitude modulation is a process of radio
broadcasting.
 Ionosphere is much effective.
 Radio antenna use for pick up
radio signals at a time.

10.  Shortwave radios can be used
communication service .
 Shortwave radio is used for
broadcasting of voice and
music for long distance.
 Short waves used in transceiver to send and receive
Morse code messages from all over the United States.

11.  Television waves are also carried by radio waves.
 Most TV stations broadcast radio waves
that have shorter wavelengths
and higher frequencies.
 Some waves carrying TV
signals are transmitted to
satellites around the Earth.

12.  Microwaves is a subset
of radio waves .
 They have wavelengths
ranging from as long as
1m to as short as 1mm
and frequencies in the
range of 1GHz to
300GHz

13.  Today many artificial
sources of microwaves
are available for use
like CMBR, Maser etc.
other then the main
and natural source viz. sun.
 Over exposure of Microwaves may have
carcinogenic effect. It includes serious burns and
can produce cataracts.

14.  These waves are used in communication
 Most radio astronomy uses
microwaves.
 It is also used in navigation.
 Also used in microwave
oven to cook food.

15.  Radar (radio detection and
ranging)- microwaves
used to detect the speed
and location of an object.
Radar uses microwave to
detect the range, speed
and other characteristics
of remote objects

16.  Shorter wavelength and higher frequencies.
 Infrared waves are emitted by the sun and objects that
emit heat. The higher the temperature
the more the infrared radiation.
 The Infrared light is emitted
or absorbed by molecules
when they change their
rotational and vibrational
movements

17.  Infrared Waves are used in Night Vision equipments
when there is no much light to see.
 Infrared Radiations are also used in tracking- known as
infrared homing .
 Infrared rays data transmission is also employed in
short range communication among computer
peripherals
 Infrared radiation can be used as a deliberate heating
source.

18.  Images of human being taken by
thermal camera, radiating infrared
waves
 Image of our globe showing
temperature all over the Earth

19. • The light we see with our eyes
is really a very small portion
of the EM spectrum.
• A RAINBOW shows the
Optical part of the EM
spectrum; Infrared would be
located just beyond the red side of the rainbow with
ultraviolet appearing just beyond the violet end.

20.  Longest wavelength is red.
 Shortest wavelength is violet.
 Colors oflight
is the visible
spectrum.
 This Part
of spectrum
is similar to
rainbows or
white light
spectrum produced by prism.

23.  The wavelength of UV rays have higher
energy and is shorter than the violet end
of the visible spectrum.
 Some insects can “see”
ultraviolet light .

Sun emits a extensive .
amount of UV waves. .

24.  They are too energetic that they can break chemical
bonds making molecules unusually reactive or ionizing.
 The disruptive effects of UV radiation on
skin cells can cause Sunburn, or Skin
cancer.
 It can irreparably damage the complex
DNA molecules in the cells.
 The sun emits a large amount of UV radiation, which
could potentially turn Earth into a barren desert.
Ultraviolet waves are of 3 types.
[NUV,EUV,FUV]
NUV
FUV
FUV
EUV
EUV
FUV
NUV

25.  In Spectrum both rays are mostly shown together as the
electromagnetic radiation emitted by X-ray tubes almost
invariably had a longer wavelength than the radiation
emitted by radioactive nuclei (gamma rays).
 The distinction between X-rays and gamma rays has
changed in recent decades only

26.  The gamma ray photon is identical to an x-ray, since
both are electromagnetic rays.
 The terms x-ray and gamma rays are statements about
origin rather than implying different kinds of radiation.
 Gamma rays, X-rays, visible light, and radio waves are all
forms of electromagnetic radiation.
 The only difference is the frequency and hence the
energy of the photons.

27.  They are shorter in wavelength than UV rays and longer
than gamma rays.
 The discoverer of X-Rays, Wilhelm Conrad Röntgen had
named it X-radiation to signify an unknown type of
radiation.
 X-rays carry great deal of
energy and can travel through
a variety of materials.
 In universe,X-rays are emitted
by pulsars, black holes
supernovas

28.  X-rays are used to examine soft tissues by
CAT or CT scanning.
 X-rays are useful in the
detection of pathology of the skeletal system
 X-rays are used as a treatment is known
as radiation therapy.

29.  X-ray microscopic analysis is used to
produce images of very small objects.
 Industrial radiography uses X-rays for inspection of
industrial parts, particularly welds.
 For security, scanners use X-rays for
inspecting the interior of luggage etc.
 X-rays are also used for Fine Art
Photography

30.  The part to be X-rayed is placed between
the X-ray source and the image receptor
to produce a shadow of the internal
structure .
 X-rays are partially attenuated by dense
tissues and pass more easily through
soft tissues.
 Areas where the X-rays strike
darken when developed,
causing denser tissues to
appear lighter than the
surrounding soft tissue

31.  The term gamma ray is used to denote electromagnetic
radiation from the nucleus as a part of a radioactive
process.
 The energy of nuclear
radiation is extremely high
 Shorter wavelength and higher frequencies of all
EM waves.

32.  Too Much exposure of Gamma Rays can kill cells
 Gamma rays are the main reason for mutations.
 In interactions with matter, gamma rays are ionizing
radiation and produce physiological effects.

33.  The Moon as seen by the Compton Gamma
Ray Observatory, in gamma rays of greater
than 20 MeV.
 Image of entire sky in 100 MeV or
greater gamma rays
 A hypernova. Artist's illustration
showing the life of a massive star as
nuclear fusion converts lighter
elements into heavier ones

34.  Gamma Rays are used to estimate the extragalactic
background light in the universe.
 Gamma radiation is often used to kill living organisms,
in a process
called
irradiation.
 Gamma rays are
also used to
treat some
types of cancer

35.  Gamma-induced molecular changes can also be used to
alter the properties of semi-precious stones, and is often
used to change white topaz into blue topaz.
 Gamma rays detectors like VACIS
are used to screen merchant ship
containers, and other loading
vehicles like Truck.
 Gamma rays are also used for diagnostic
purposes in nuclear medicine in imaging
techniques.