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Slide 1
Slide 2
The angle between the incident ray and the emergent ray is
called the angle of deviation. It is represented by
Slide 3
The angle of incidence at the first surface (i) The angle of
Prism (A) The R.I. of the material of the prism ()
Slide 4
White Light : Its a polychromatic light and has all the seven
wavebands present in it. Monochromatic Light: A light which
consists of one colour (one wavelength) only is called
monochromatic light
Slide 5
A light, which is a mixture of several colours (waveband) is
called polychromatic light.
Slide 6
The phenomenon of splitting of white light into its constituent
colours is known as DISPERSION
Slide 7
The band of colours obtained on the screen, when a
polychromatic light splits into component colours is called a
Visible spectrum.
Slide 8
When white light is incident on the first surface of a prism
and enters it, light of different colours is refracted (or
deviated) through different angles. CAUSE OF DISPERSION
Slide 9
Slide 10
FREQUENCY AND WAVE LENGTH OF VISIBLE SPECTRUM C = f C= speed of
light. = wavelength of light f = frequency of light
Slide 11
COLOUR It is a sensation produced in the brain due to the
excitation of the retina, by an E.M.Wave of some particular
wavelength
Slide 12
Color FrequencyFrequency in 10 14 Hz WavelengthWavelength
violet 6.737.5 4000 4460 blue 6.016.48 4640 5000 green
5.196.0150005780 yellow 5.085.1957805920 orange 4.845.08 59206200
red 3.75 4.84 62008000
Slide 13
Electromagnetic Waves & the Electromagnetic Spectrum
Slide 14
Electromagnetic Waves Transverse waves without a medium! (They
can travel through empty space)
Slide 15
They travel as vibrations in electrical and magnetic fields.
Have some magnetic and some electrical properties to them.
Slide 16
When an electric field changes, so does the magnetic field. The
changing magnetic field causes the electric field to change. When
one field vibratesso does the other. RESULT-An electromagnetic
wave.
Slide 17
Electromagnetic Spectrumname for the range of electromagnetic
waves when placed in order of increasing frequency RADIO WAVES
MICROWAVES INFRARED RAYS VISIBLE LIGHT ULTRAVIOLET RAYS X-RAYS
GAMMA RAYS
Slide 18
Notice the wavelength is long (Radio waves) and gets shorter
(Gamma Rays)
Slide 19
RADIO WAVES Have the longest wavelengths and lowest frequencies
of all the electromagnetic waves.
Slide 20
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.
Slide 21
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. # on radio dial tells frequency.
Slide 22
MRI (MAGNETIC RESONACE IMAGING) Uses Short wave radio waves
with a magnet to create an image.
Slide 23
MICROWAVES Have the shortest wavelengths and the highest
frequency of the radio waves.
Slide 24
Used in microwave ovens. Waves transfer energy to the water in
the food causing them to vibrate which in turn transfers energy in
the form of heat to the food.
Slide 25
RADAR (Radio Detection and Ranging) Used to find the speed of
an object by sending out radio waves and measuring the time it
takes them to return.
Slide 26
INFRARED RAYS Infrared= below red Shorter wavelength and higher
frequency than microwaves.
Slide 27
PROPERTIES They are not affected by electric or magnetic field.
They travel with the velocity of light. They obey the laws of
reflection and refraction. They are least scattered by fog, mist,
etc.
Slide 28
Their wavelength is between 0.8m to 40m. They do not affect
ordinary photographic film. They can be detected by a thermopile or
a thermometer.
Slide 29
You can feel the longest ones as warmth on your skin Warm
objects give off more heat energy than cool objects.
Slide 30
Thermograma picture that shows regions of different
temperatures in the body. Temperatures are calculated by the amount
of infrared radiation given off. Therefore people give off infrared
rays. Heat lamps give off infrared waves.
Slide 31
VISIBLE LIGHT Shorter wavelength and higher frequency than
infrared rays. Electromagnetic waves we can see. Longest
wavelength= red light Shortest wavelength= violet (purple)
light
Slide 32
ULTRAVIOLET RAYS Shorter wavelength and higher frequency than
visible light Carry more energy than visible light
Slide 33
PROPERTIES They are e.m.waves and are not effected by electric
or magnetic field. They travels with the velocity light. The range
of these radiations is between 4000A to 100A They produce chemical
effect in sliver.
Slide 34
PROPERTIES They obeys the laws of reflection and refraction.
They are absorbed by the atmosphere and convert oxygen to ozone.
They produced fluorescence in substance like zinc sulphide, barium
sulphide, etc.
Slide 35
Too much can cause skin cancer. Use sun block to protect
against (UV rays)
Slide 36
Causes your skin to produce vitamin D (good for teeth and
bones)
Slide 37
X- RAYS Shorter wavelength and higher frequency than UV-rays
Carry a great amount of energy Can penetrate most matter.
Slide 38
PROPERTIES X-Ray are e.m.wave of very short wavelength ranging
from 10 -12 m to 10 -10 m. They are not effected by electric and
magnetic field. They effect the photographic plate intensely.
Slide 39
PROPERTIES They travel in vacuum with the speed of light. They
ionize the gas through which they pass. X-ray undergo reflection
and refraction.
Slide 40
Bones and teeth absorb x-rays. (The light part of an x-ray
image indicates a place where the x-ray was absorbed)
Slide 41
Too much exposure can cause cancer (lead vest at dentist
protects organs from unnecessary exposure)
Slide 42
Used by engineers to check for tiny cracks in structures. The
rays pass through the cracks and the cracks appear dark on
film.
Slide 43
GAMMA RAYS Shorter wavelength and higher frequency than X-rays
Carry the greatest amount of energy and penetrate the most.
Slide 44
Properties Have velocity equal to that of light. Have high
penetrating power. They can penetrate through several centimeters
thick iron and lead blocks. They have got small ionizing power.
They can effect a photographic plate.
Slide 45
Properties They can produce heating effect in the surface
exposed to them. They are not deflected by electric and magnetic
fields. They knock out electrons from the surface on which they
fall.
Slide 46
Used in radiation treatment to kill cancer cells. Can be very
harmful if not used correctly.
Slide 47
Exploding nuclear weapons emit gamma rays.
Slide 48
Rayleigh Scattering When a photon penetrates into a medium
composed of particles whose sizes are much smaller than the
wavelength of the incident photon, the scattering process is
elastic and is called Rayleigh scattering. In this scattering
process, the energy (and therefore the wavelength) of the incident
photon is conserved and only its direction is changed. In this
case, the scattering intensity is proportional to the fourth power
of the reciprocal wavelength of the incident photon. The scattering
of electromagnetic radiation by particles with dimensions much
smaller than the wavelength of the radiation, resulting in angular
separation of colors and responsible for the reddish color of
sunset and the blue of the sky.
Slide 49
Light Scattering When light encounters matter, matter not only
re-emits light in the forward direction (leading to absorption and
refractive index), but it also re- emits light in all other
directions. This is called scattering. Light scattering is
everywhere. All molecules scatter light. Surfaces scatter light.
Scattering causes milk and clouds to be white and water to be blue.
It is the basis of nearly all optical phenomena. Scattering can be
coherent or incoherent.