The document provides an overview of the history of radiation, including key discoveries and events. It describes Wilhelm Roentgen's discovery of X-rays in 1895, Henri Becquerel's accidental discovery of radioactivity in uranium in 1896, and Marie and Pierre Curie's isolation of the radioactive elements polonium and radium in 1898. It also discusses the radium dial painters who suffered health impacts from radium exposure in the early 20th century. Finally, it outlines the 1986 Chernobyl disaster, considered the worst nuclear power plant accident, which occurred at a reactor in Ukraine and spread radioactive debris over parts of Europe.

1. RADIATION AND THE HISTORY
SALONI CHAWLA

2. CONTENTS
• WHAT IS RADIATION ?
• TYPES OF RADIATION
• DISCOVERY OF X RAYS
• DISCOVERY OF RADIOACTIVITY
• RADIUM GIRLS
• NUCLEAR POWER PLANT
• CHERNOBYL ACCIDENT
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3. RADIATION
• In general , Radiation is the emission and
propagation of energy in the form of waves or
Particles .
• Eg :Sound ,light, x-rays , UV rays , Heat etc
• It can travel through medium or vacuum.
• In Physics, we take radiation in the form of
electromagnetic waves or particles.
• Eg :light, x-rays , UV rays etc
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4. EM SPECTRUM
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5. A TOUCH OF QUANTUM MECHANICS
• The idea of a radiation being a wave or particle
became vague when the WAVE PARTICLE theory
came into the scene .
• DE BROGLIE hypothesis says that the wave can act as
a particle sometimes and also sometimes electrons
,protons etc can behave as waves.
• This can be clearly explained by the PHOTOELECTRIC
EFFECT .
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6. • De Broglie wavelength is given by Lambda=h/p
Or h/mv .
• λ is indirectly proportional to velocity and
mass
• All the macroscopic bodies do have
wavelength associated with them but that is
too small to observed.eg football
• Also Heisenberg uncertainty principle says
that when we try to find the position its
momentum become undefined and vice versa
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7. MORE ABOUT HEISENBERG
• The uncertainty principle says that we cannot
measure the position (x) and the momentum (p)
of a particle with absolute precision.
• The more accurately we know one of these
values, the less accurately we know the other.
• Multiplying together the errors in the
measurements of these values has to give a
number greater than or equal to half of a
constant called "h-bar".
• This is equal to Planck's constant (usually written
as h) divided by 2π.
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8. • One way to think about the uncertainty principle is as an
extension of how we see and measure things in the everyday
world.
• You can read these words because particles of light, photons,
have bounced off the screen or paper and reached your eyes.
Each photon on that path carries with it some information
about the surface it has bounced from, at the speed of light.
• Seeing a electron, is not so simple. You might similarly
bounce a photon off it and then hope to detect that photon
with an instrument.
• But chances are that the photon will impart some momentum
to the electron as it hits it and change the path of the particle
you are trying to measure. Or else, given that quantum
particles often move so fast, the electron may no longer be in
the place it was when the photon originally bounced off it.
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9. CLASSIFICATION
 Ionizing Radiation
– Higher energy electromagnetic waves (gamma) or
heavy particles (beta and alpha).
– High enough energy to pull electron from orbit.
 Non-ionizing Radiation
– Lower energy electromagnetic waves.
– Not enough energy to pull electron from orbit, but
can excite the electron.
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10. TYPES OF IONISING RADIATION
1.DIRECTLY IONISING RADIATION
• Energy > 13.6 ev
• Ionisation of an atom
• CHARGED
• Eg : electrons , protons or alpha ,beta etc
2. INDIRECTLY IONISING RADIATION
• Energy <13.6 ev
• Two step interaction
• UNCHARGED
• Eg x rays , gamma rays etc
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11. Can a non ionising radiation be
an indirectly ionising one ?
FOOD FOR THOUGHT ...

12. X RAYS
• Wilhelm Conrad Roentgen , a German physicist
discovered X rays on November 8,1895.
• He was investigating the behaviour of cathode rays in
high energy cathode ray tube
• It consists of a glass envelope from as much air as
possible was evacuated
• He covered the CRT with black paper to ensure that
light does not escape and also to block outside light .
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13. • He also darkened the laboratory room .
• He found that whenever the cathode ray was
organised the unknown type of ray was
produced .
• This ray caused the fluorescence of a small
paper coated with barium platinocyanide .
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14. • This could not be electrons from cathode ray
• This could not be the light because it is all dark
and cardboard was also there in between them.
• There is something that cross the tube when CRT
is organised and also penetrate the cardboard
• Excitement increased and he kept different things
in between them replacing cardboard results
were different
• Then he held his hand between the tube and the
fluorescent screen and the result was ...
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15. RESULT
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16. • The skeleton of his hand appeared on the
screen .
• He called it X RAYS, because he was still
unknown of this radiation .
• This led him to win NOBEL PRIZE IN 1901
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18. BACKGROUND
• HENRI BECQUEREL was a scientist who worked on
minerals and optics .
• He belonged to a family of scientist ,Grandfather
discovered piezoelectricity and father phosphoresce.
• After discovery of x rays , Becquerel was trying to find
out whether these are related to phosphorescence or
not .
• He took Uranium salts and photographic film covered
with black paper and thought if the X-rays were coming
out from phosphorescent* material it will cross film
and form a image provided we need to give a UV
radiations ie Sun.
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19. DISCOVERY
• Those days in February , Paris was short of sunshine .
• Becquerel had to delay his experiment .He kept the
Uranium minerals and film in the drawer .
• After week or so he decided to develop film though
sunshine was not there
• He found that the photographic film had an impression
• Even when uranium was not phosphorescent .
• He was dumbstruck ,seeing it as he hypothesised that
Uranium salts are sources of X-rays .
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20. RESULT
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21. RESEARCH CONTINUES
• To continue the research RUTHERFORD came
• His topic of concern was to study the rays given out
by URANIUM
• He discovered that the rays by Uranium are not X
rays they are some other rays .
• He gave three rays alpha beta and gamma which
comes from some special substance
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22. EXPERIMENT
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23. AND IT DIDNOT STOP!
MARIE CURIE : MOTHER OF MODERN PHYSICS
• The term radioactivity was actually coined by Marie Curie,
who together with her husband Pierre, began investigating
the phenomenon recently discovered by Becquerel.
• She worked on the uranium ore pitchblende and found that
it emitted much more radioactivity than the uranium in the
mineral could deliver .
• It must contain another highly radioactive element, yet
unknown.
• In 1898, PIERRE AND MARIE ,discovered two new elements
- polonium and radium.
• Polonium was named after Marie's homeland, Poland.
Radium got its name from the Latin word for ray..
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24. RADIUM GIRLS
• There was a factory of radium watches which
hired 70 WOMEN to paint RADIUM DIAL .
• Ii was called UNDARK paint made of glue ,water
and radium powder .
• Women wee taught to shape paintbrush with
mouths to maintain a fine point
• Some painted their nails and teeth too with that
paint
• Management and scientist kept themselves away
from the exposure but the workers were unaware
of it .
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25. • Five Radium Girls sued U.S.
Radium in a case that
initiated labour safety
standards and workers'
rights.
• Workers suffered from
inexplicable bone fractures,
bleeding gums and
eventually, necrosis of the
jaw.
• The Radium Girls' case was
settled in 1928, putting a
swift end to shaping
paintbrushes with the
mouth and open containers
of radium paint.
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26. NUCLEAR POWER PLANT
• In nuclear power station, electrical power is
generated by nuclear reaction.
• Here, heavy radioactive elements such as Uranium
(U235) or Thorium (Th232) are subjected to nuclear
fission. This fission is done in a special apparatus
called as reactor.
• FISSION : The nuclei of heavy radioactive atoms are
broken into two nearly equal parts. During this
breaking ,huge quantity of energy is released. This
release of energy is due to mass defect. (mass of final
products are reduced than initial )
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27. • It is same as steam power station. Only difference is
that, instead of using heat generated due to coal
combustion , here heat is generated due to fission
• Heat is used to produce steam from water in the
boiler. This steam is used to drive a steam turbine.
This turbine is the prime mover of the alternator
which generates electrical energy.
• Very less amount of nuclear fuel can generate huge
amount of electrical energy. This is the unique
feature of a nuclear power plant.
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28. • One kg of uranium is equivalent to 4500
metric tons of high grade coal. That means
complete fission of 1 kg uranium can produce
as much heat as can be produced by complete
combustion of 4500 metric tons high grade
coal.
• To meet up conventional fuel crisis in present
era, nuclear power station can be the most
suitable alternatives.
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29. DIFFERENT COMPONENTS OF
NUCLEAR POWER STATION
The plant consists of mainly following parts:
1 NUCLEAR REACTOR
2 HEAT EXCHANGER
3 STEAM TURBINE
4 ALTERNATOR
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30. WORKING
• In nuclear fission, the nuclei of nuclear fuel, such as U235
are bombarded by slow flow of neutrons.
• Uranium is broken, huge heat energy released and also
number of neutrons are emitted during breaking .
• These neutrons cause further fission which needs to be
controlled
• These neutrons should be removed otherwise explosion
can occur .
• Cadmium rods are used because they are good absorber
of neutrons called control rods they are moveable .
• There is also moderator to slow down the neutrons .
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31. • Heat Exchanger: The heat carried by sodium metal,
is dissipated in water and water is converted to high
pressure steam here.
After releasing heat in water the sodium metal
coolant comes back to the reactor by means of
coolant circulating pump.
• Steam Turbine :In nuclear power plant, the steam
drives the turbine in the same way. After doing its
job, the exhaust steam comes into steam condenser
where it is condensed to water and can be reused.
• Alternator :an electrical generator that converts
mechanical energy to electrical energy in the form of
alternating current
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33. CHERNOBYL DISASTER
The worst manmade disaster in human history
Czech Technical University In Prague
23 May 2007

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WHERE IS CHERNOBYL?

35. CHERNOBYL ACCIDENT
• NUCLEAR power plant is located 11 miles from the city
of Chernobyl
• Plant consisted of 4 reactors while 5 and 6 reactors
were under construction each capable of producing
1GW of ELECTRIC POWER
• On Saturday, April 26, 1986, at 1:23:58 a.m. local time,
the fourth reactor of the Chernobyl power plant
known as Chernobyl-4 suffered a catastrophic steam
explosion that resulted in a fire, a series of additional
explosions, and a nuclear meltdown.
• It is regarded as the worst nuclear accident . It
produced radioactive debris that drifted over parts the
western soviet union Scandinavia, UK, and even
eastern USA.
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36. WHAT HAPPENED?
•Reactor 4 was undergoing a
test to test the backup power
supply in case of a power
loss.
•The power fell too low,
allowing the concentration of
xenon-135 to rise.
•The workers continued the
test, and in order to control
the rising levels of xenon-135,
the control rods were pulled
out.

37. WHAT HAPPENED?
• The experiment involved shutting down the coolant
pumps, which caused the coolant to rapidly heat up and
boil.
• Pockets of steam formed in the coolant lines. When the
coolant expanded in this particular design, the power
level went up.
• All control rods were ordered to be inserted. As the rods
were inserted, they became deformed and stuck. The
reaction could not be stopped.
• The rods melted and the steam pressure caused an
explosion, which blew a hole in the roof

38. THE CHERNOBYL REACTOR AFTER THE
EXPLOSION.

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DIRECT CASUALTIES
• 5.5 million people still live in contaminated
areas
• 31 people died in 3 months of radiation
poisoning
• 134 emergency workers suffered from acute
radiation sickness
• 25,000 rescue workers died since then of
diseases caused by radiation
• Increased birth defects, miscarriages, and
stillbirths

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INDIRECT CASUALTIES
• By the year 2000 there
were 1800 case of
thyroid cancer in
children and
adolescent.
• High number of suicide
and violent death
among Firemen,
policemen, and other
recovery workers

41. Bibliography
• www.physicspages.com
• www.earthmagazine.com
• www.electricals4u.com
• Radiation detection and measurement by
SAHA
• Christensen book on XRAY PRODUCTION
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