The document provides background information on the atom and its structure. It discusses:
1) The historical discovery of x-rays by Wilhelm Roentgen in 1895 and some of his early experiments.
2) The basic structure of atoms, which consists of a small, positively charged nucleus surrounded by negatively charged electrons.
3) The concept of atomic number and electron shells or orbits within atoms.
4) Different types of ionizing radiation including particulate radiation like alpha and beta particles, and electromagnetic radiation like x-rays and gamma rays.
Technical Overview: LENR nucleosynthetic networks beginning with Nickel ‘seed’ nuclei; why cascades of fast beta-decays are important; and why end-products of LENR networks are mostly stable isotopes without significant concomitant emissions of 'hard' gamma and neutron radiation as is typical with better-known commercial fission and hoped-for fusion technologies.
Technical Overview: LENR nucleosynthetic networks beginning with Nickel ‘seed’ nuclei; why cascades of fast beta-decays are important; and why end-products of LENR networks are mostly stable isotopes without significant concomitant emissions of 'hard' gamma and neutron radiation as is typical with better-known commercial fission and hoped-for fusion technologies.
RADIOACTIVITY
Atomic theory
In chemistry and physics, the atomic theory explains how our understanding of the atom has changed over time. Atoms were once thought to be the smallest pieces of matter.
The first idea of the atom came from the Greek philosopher Democritus. A lot of the ideas in the modern theory came from John Dalton, a British chemist and physicist.
Democritus' atomic theory
The nanoscience is study of production of material of size as small as nanometer size, in practice a material should be of size between 1nm to 100nm at least one of three dimensions to be called a nanomaterial. The properties of material different from its bulk counterpart when it reduced its dimensions to nanoscale. Here some fundamentals about nanoscience, nanotechnology, properties and materials is discussed.
RADIOACTIVITY
Atomic theory
In chemistry and physics, the atomic theory explains how our understanding of the atom has changed over time. Atoms were once thought to be the smallest pieces of matter.
The first idea of the atom came from the Greek philosopher Democritus. A lot of the ideas in the modern theory came from John Dalton, a British chemist and physicist.
Democritus' atomic theory
The nanoscience is study of production of material of size as small as nanometer size, in practice a material should be of size between 1nm to 100nm at least one of three dimensions to be called a nanomaterial. The properties of material different from its bulk counterpart when it reduced its dimensions to nanoscale. Here some fundamentals about nanoscience, nanotechnology, properties and materials is discussed.
CONTENTS
INTRODUCTION
NEED FOR CYBER LAWS
CYBER LAWS IN INDIA
CYBER CRIMES
OFFENCES AND LAWS IN CYBER SPACE
CYBER LAWS AMENDMENTS
CONCLUSION
INTRODUCTION
What is Cyber Law?
Cyber Law is the lawgoverning cyber space.Cyber space is a very wideterm and includescomputers, networks,software, data storagedevices (such as hard disks,USB disks etc), theInternet, websites, emailsand even electronic devicessuch as cell phones, ATMmachines etc.
Cyber lawencompasses lawsrelating to
:
1. Cyber Crimes
2. Electronic and DigitalSignatures
3. Intellectual Property
4. Data Protection andPrivacy
NEED FOR CYBER LAWS
TACKLING CYBERCRIMES
INTELLECTUALPROPERTYRIGHTS ANDCOPYRIGHTSPROTECTION ACT
NEED FOR CYBER LAWS
1. Cyberspace is an
intangible
dimension that is impossible togovern and regulate usingconventional law.
2. Cyberspace has complete
disrespect for jurisdictionalboundaries
. A person in Indiacould break into a bank’selectronic vault hosted on acomputer in USA and transfermillions of Rupees to anotherbank in Switzerland, all withinminutes. All he would need is alaptop computer and a cellphone.
3. Cyberspace
handlesgigantic traffic volumesevery second
. Billions ofemails are crisscrossing theglobe even as we read this,millions of websites are beingaccessed every minute andbillions of dollars areelectronically transferredaround the world by banksevery day.
4. Cyberspace is
absolutelyopen to participation by all.
A ten year-old in Bhutan canhave a live chat session with aneight year-old in Bali withoutany regard for the distance orthe anonymity between them
ABOUT AUTHOR
Sumit Verma
Chitkara University
Undergraduate
PAPERS
1
FOLLOWERS
575
Follow
RELATED PAPERS
Important question answers Information Technology Act, 2000
Suvo Chatterjee
Download
More Options
IT ACT 2000 – PENALTIES, OFFENCES WITH CASE STUDIES From
aru mugam
Download
More Options
Information Technology
trinisha chakroborty
Download
More Options
OVERVIEW OF CYBER LAWS IN INDIA Index
aneesh tvm
Download
More Options
Critical analysis of proposed cyber Crime Bill 2015
Shahid Jamal T U B R A Z Y Cyber Lawyer
Download
More Options
Final Cyber Cri
Prashant Dabhade
Download
More Options
Cyber Laws in India
Vikas Khatkar
Download
More Options
Commentary on THE INFORMATION TECHNOLOGY ACT, 2000
Rohas Nagpal
Download
More Options
INTRODUCTION TO THE ACT 2. NEED AND OBJECTIVES 3 ROLE OF IT IN ECOMMERCE 4 CYBER CRIME 5 ELECTRONIC SIGNATURES 6 E-GOVERNANCE
keshav agarwal
Download
More Options
NON BAILABLE OFFENCES( Cyber Crimes) UNDER The IT Act, 2000 (Cyber Law)
Adv Prashant Mali, Ph.D.
Download
More Options
P a g e Fundamentals of Cyber Law Rohas Nagpal Asian School of Cyber Laws
vijay onlinesangli
Download
More Options
SEMINAR AND WORKSHOP ON DETECTION OF CYBER CRIME AND INVESTIGATION Presented by
chayapathi A R
Download
More Options
Cyber Crime Investigation and Trial Procedure in Bangladesh: Comparison with India
Thohedul Islam Talukdar
Down
This was created using a template from Canva. This was also created by students when they were asked to report for a specific topic namely "Atomic and Nuclear Physics." This can serve as a reviewer for students who want to study about this topic.
"Management of the Patient Irradiated for Head and Neck Cancer"Jansen Calibo
"Management of the Patient Irradiated for Head and Neck Cancer"
A.Effects of Radiation or Chemotherapeutic Drug
B. Prevention & Management of the Effects of Radiation & Chemotherapy
C.The Use of Hyperbaric Oxygen Therapy
D.The Use of Lasers & Cryosurgery in Oral & Maxillofacial Surgery
2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
Biological screening of herbal drugs: Introduction and Need for
Phyto-Pharmacological Screening, New Strategies for evaluating
Natural Products, In vitro evaluation techniques for Antioxidants, Antimicrobial and Anticancer drugs. In vivo evaluation techniques
for Anti-inflammatory, Antiulcer, Anticancer, Wound healing, Antidiabetic, Hepatoprotective, Cardio protective, Diuretics and
Antifertility, Toxicity studies as per OECD guidelines
Synthetic Fiber Construction in lab .pptxPavel ( NSTU)
Synthetic fiber production is a fascinating and complex field that blends chemistry, engineering, and environmental science. By understanding these aspects, students can gain a comprehensive view of synthetic fiber production, its impact on society and the environment, and the potential for future innovations. Synthetic fibers play a crucial role in modern society, impacting various aspects of daily life, industry, and the environment. ynthetic fibers are integral to modern life, offering a range of benefits from cost-effectiveness and versatility to innovative applications and performance characteristics. While they pose environmental challenges, ongoing research and development aim to create more sustainable and eco-friendly alternatives. Understanding the importance of synthetic fibers helps in appreciating their role in the economy, industry, and daily life, while also emphasizing the need for sustainable practices and innovation.
Introduction to AI for Nonprofits with Tapp NetworkTechSoup
Dive into the world of AI! Experts Jon Hill and Tareq Monaur will guide you through AI's role in enhancing nonprofit websites and basic marketing strategies, making it easy to understand and apply.
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
Francesca Gottschalk - How can education support child empowerment.pptxEduSkills OECD
Francesca Gottschalk from the OECD’s Centre for Educational Research and Innovation presents at the Ask an Expert Webinar: How can education support child empowerment?
Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdfTechSoup
In this webinar you will learn how your organization can access TechSoup's wide variety of product discount and donation programs. From hardware to software, we'll give you a tour of the tools available to help your nonprofit with productivity, collaboration, financial management, donor tracking, security, and more.
A Strategic Approach: GenAI in EducationPeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
BÀI TẬP BỔ TRỢ TIẾNG ANH GLOBAL SUCCESS LỚP 3 - CẢ NĂM (CÓ FILE NGHE VÀ ĐÁP Á...
Roentgenology X-ray
1. Roent Lec 1
NATURE OF THE ATOM
Historical Background - Matter is a physical manifestation possessing mass
(occupies space and has weight) and having form or
- X-rays were discovered in Nov. 8, 1895 by William
shape.
Konrad Roentgen (pronounced as “rentken”)
- Elements are simple substances that cannot be
- He pioneered 3 keys areas of x-ray imaging:
decomposed by ordinary means.
1. An x-ray photograph of his closed wooden box
- There are 105 known elements at present.
of weights clearly revealed its contents, thus
- The atom is the smallest particle of an element that
presaging the security application found at
has characteristic properties of that element.
every airport check-in.
- Each atom consists of a small nucleus, which has a
2. An x-ray image of his hunting rifle revealed a
positive charge and a number of lighter particles
flaw inside the metal of the gun. This was the
with negative charges called electrons, which move
first time a hidden structural flaw had been
around the nucleus in definite orbits.
exposed without destroying the object.
- The atom is said to be neutral when the net number
3.
of positive charges of the nucleus (protons) equals
4. He took a permanent x-ray photograph of his
the negative charges of the orbital electrons.
wife Bertha’s left hand, revealing the bones and
- The closer of the electrons to the nucleus, the higher
the rings that she was wearing.
energy level.
- The electrons are kept in their orbits by the balance
between:
1. The electrostatic attraction of unlike charges.
2. The centrifugal forces of the fast moving
electrons.
ATOMIC NUMBER
- The atomic number, or Z number, is the no. of
…(taken: January 1896 by Roentgen)
protons in the nucleus or the no. of electrons
outside the nucleus.
- Z number range from 1 for the simplest atom
-The hand of the cadaver, they injected (Hydrogen) to 105 for the most complex atom yet
mercury that reveals the architecture of discovered (Hahnium).
the hand.
Orbital Electrons
- Electrons are very small particles carrying 1 unit of
Amputated negative charge.
hand after
- They revolve around the nucleus in well-defined
exposure to
shells that exist at varying distances from the
too much
radiation nucleus.
for 5 years.- - A maximum no. of seven potential electron-
containing orbits or shells are designated as
K,L,M,N,O,P and Q in order of increasing distance
from the nucleus.
- Roentgen was awarded the first Nobel Prize for Physics in
- Electrons in the
1901.
most outermost
- Roentgen announced to the word the discovery of the
shell are termed
new kind of ray in 1895; he called it the “X-ray” after the
valence electrons
algebraic symbol for unknown.
and determine the
- Otto Walkhoff, DDS, MD completed the first dental
chemical
radiograph ever med in January 14, 1896.
properties of the
- Dr. Otto Walkhoff- first dental radiograph 25minute
atom.
exposure (< 0.5 seconds today).
2. electron has a negative charge (-1) thus, an ion pair
ELECTRON ORBITS OR SHELLS has been formed.
- The electrons in an atom do not spontaneously fly
off from the nucleus by centrifugal force or, on the IONIZING RADIATION
other hand, drop into the nucleus by electrostatic
Types of Ionizing Radiation
attraction (unlike charges attract), because in the
-Corpuscular or Particulate radiation
normal atom there is a balance between centrifugal
- Electromagnetic radiation
and electrostatic force.
- This balance results in a definite electron path or
PARTICULATE RADIATION
orbit for each electron around the nucleus.
- Particulate radiations are actually minute particles of
- Each shell has a different energy level which is
matter that travel in straight lines at high speeds
dependent on the atomic no. of the atom and
from their sources.
distances the electron from the nucleus.
- Although incredibly small, they possess mass.
- The attractions force is greater when the electron
- All are charge electrically, except neutrons, and they
shell is nearer the nucleus.
all move extremely fast- sometimes as fast as light.
- Thus, it would require more work (energy) to
- Alpha Particles are composed of a combination of
remove an electron from the K shell and out of range
two protons and two neutrons.
of the nuclear electric field than to remove an
- It is the helium nucleus without orbital electrons.
electron from one of the outer shells.
- Alpha particles are emitted only from the nuclei of
BINDING ENERGIES heavy metals.
- The energy required to remove an electron from a - Compared with the other particles, the alpha particle
particular shell is designated as binding energy of is enormous and exerts a large electrostatic
that shell. attraction.
- The binding energy is characteristic of a given - They have little ability to penetrate tissues and give
element and shell. up their large energies within a very short distance in
- This is the kinetic energy of an electron accelerated air (5cm) and in soft tissue (100 um).
through a potential difference of 1 volt. - Beta Particles (Negatrons) are emitted from the
- Larger multiple units of the electron volt are nucleus of radioactive atoms and possess 1 unit of
frequently used: kcV for 1000 or kiloelectron volts, negative charge.
and McV for 1 million or megaelectron volts. - They have very small atomic masses.
- Beta particles more penetrating that alpha particles
IONIZATION and may penetrate 10- 100 cm of air and
- Ionization is the process by which a neutral atom or approximately 1-2 cm of the soft tissue.
molecule acquires either a positive or a negative - Cathode Rays (Electrons) are streams of electrons
charge. passing from the hot filament of the cathode to the
- When an atom losses or gains an electron, it is said target of the anode in an x-ray tube.
to be ionized. - Beta particles come from the nucleus of radioactive
- An ionized atom (called an ion) is not electrically atoms, whereas the cathode rays originated from
neutral but carries a charge equal to the difference the orbital electrons of the atoms of the filament
between the number of protons and electrons. material for an x-ray tube.
- An atom that is not electrically balanced is called an - Protons are accelerated hydrogen nuclei.
ion. - Because protons are heavy, charged particles, the
- In any ionization process, ion pairs are formed; it is lose kinetic energy as they penetrate matter.
this process that elicits chemical changes in matter. - Neutrons carry no electron- charge and have nearly
- When an x-ray transfers its energy to an orbital the same mass as a proton.
electron, it ejects it from the atom, and an ion pair is - The characteristic if being electrically neutral has
formed. proved of great importance in nuclear physics
- The atom becomes a positive ion (=1 charges because such a particle can penetrate into the
because it has lost an electron and the ejected nucleus of an atom without being subjected to e
3. enormous forces of a positively charged particle. 9. They cause fluorescence of certain crystals.
10. They affect photographic film (producing a latent
image which can be developed chemically).
ELECTROMAGNETIC RADIATION 11. They produce chemical and biologic changes (this is
- X-rays and gamma rays belong to a group of essential biologic cell damage and treatment of
radiation called electromagnetic radiations. malignancies, these biologic changes depend o n
- Electromagnetic radiation is the propagation of ionizations).
energy through space accompanied by electric and
magnetic force fields. WAVE CONCPET OF ELECTROMAGNETIC RADIATION
- X-rays and gamma rays belong to a group of
radiation called electromagnetic radiation. - Electromagnetic radiation is the propagation of
- X-rays are produced outside the nucleus in the wave-like energy through space or mass at the speed
4
electron orbital system. of light (186, 000 miles per second or 3 x 10 m/sec).
- Gamma rays are emitted from the nucleus of a - It is called electromagnetic radiation because the
radionuclide. energy that is radiated is accompanied by oscillating
electric and magnetic fields.
PARTICULATE and ELECTROMAGNETIC RADIATION
EXAMPLES OF ELECTROMAGNETIC RADIATION
- The radio wave that we hear.
- The light waves we see.
- The infrared waves that can take pictures in the dark.
- The ultraviolet rays that cause sunburn.
- The x-rays.
- The gamma rays of the atomic bombs.
- The cosmic rays that hinder travel in space.
NATURE OF X-RAYS Electromagnetic waves need no such medium as
- The wave concept of electromagnetic radiation they can be propagated within and transmitted
explains why it may be reflected, refracted, through a vacuum.
diffracted and polarized. All waves have an associated wavelength and
- The particle concept is used to describe the frequency.
interaction between radiation and matter. The wavelength of a wave is the distance between
two successive crests or valley, and is given the
X-RAY PROPERTIES
symbol λ (the Greek letter lambda, the symbol for
1. They are weightless packages of pure energy
length).
(photons) without an electrical charge which travel
in waves with specific frequency at speed of 186,
- The
000 miles per second (speed of light).
no. of waves
2. Invisible, highly penetrating waves (electromagnetic
passing a
waves).
particular
3. Electrically neutral (cannot be deflected by electrical
point during
or magnetic fields).
a specific
4. Wide useful range of wavelengths in medicine and
period is
dentistry = 0.01 is equal to 1 billionth of a meter).
called the
5. Most beams of x-rays are heterogeneous (consisting
frequency
of rays of many different wavelengths).
and I given
6. They emerge from the tube in straight lines,
the symbol λ
diverging form the focus of the target of the anode.
(the Greek
7. They are capable of ionizing gases because of their
letter nu, the symbol for number).
ability to remove orbital electrons from atoms.
- It is usually identified as oscillations per second or
8. They travel as the same speed as light (1866, 000
cycles per second.
miles per second in a vacuum).
- The unit of frequency measurement is the hertz (Hz).
4. - One hertz equals 1 cycle/ sec and 80 Hz is the long waves are in the radio region of the
standard 60 cycle/ sec. electromagnetic spectrum.
Dangers:
THE ELECTROMAGNETIC SPECTRUM - Large doses of radio wavesare believed to cause
cancer, leukaemia and other disorders.
What are electromagnetic waves?
- Some people claim that the very low frequency field
- All forms of electromagnetic radiation are grouped
from overhead power cables near their homes has
according to their wavelengths in what is called the
affected their health.
electromagnetic spectrum.
- All have no mass, no electrical charge and travel with
MICROWAVES
wave motion.
- Microwaves are basically extremely high frequency
- Electricity can be static like what a balloon to the wall or
radio waves, and are made by various types of
makes your hair stand on end. Magnetism can also be
transmitter in a mobile phone, they’re made by
static like a refrigerator magnet. But when they change
or move together, they make waves electromagnetic a transmitter chip and an antenna, in a
waves. microwave oven they’re made by a
- Electromagnetic waves are formed when an electric “magnetron”. Their wavelength is usually a
field (blue arrows) couples with a magnetic field (red couple of centimetres. Stars also give off
arrows). Magnetic and electric fields of an microwaves.
electromagnetic wave are perpendicular to each other Uses:
and to the direction of the wave.
- Microwaves cause water and fat molecules to
vibrate which makes the substances hot. Thus we
can use microwaves to cook many types of food.
- Microwaves have wavelengths that can be measured
in centimetres. The longer microwaves, those closer
to a foot in length, are the waves which heat our
food in a microwave oven.
- Microwaves are good for transmitting information
from one place to another because microwave
energy can penetrate haze, light rain and snow,
THE ELECTROMAGNETIC SPECTRUM clouds and smoke.
Rabbits Radio - Shorter microwaves are used in remote sensing.
Mate Microwaves These microwaves are used for radar like the
In Infra-Red doppler radar used in weather forecasts.
Very Visible light - Microwaves, used for radar, are just a few inches
Unusual Ultra-violet long. This microwave tower can transmit information
eXpensive X-rays like telephone and computer data from one city to
Gardens Gamma rays another.
- Because microwaves can penetrate haze, light rain,
RADIO WAVES snow, clouds and smoke, these waves are good for
- Radio waves are made by various types of viewing the earth from space.
transmitter depending on the wavelength. They are - Mobile phones use microwaves as they can be
also given off by stars sparks and lightning which is generated by asmall antenna which means that the
why you hear interference on your radio in a phone doesn’t need to be very big. The drawback is
thunderstorm. that, being small, they can’t put out much power and
- Objects in space, such as planets and comets, giant they also need a line of sight to the transmitter. Thus
clouds of gas and dust, and stars and galaxies, emit means that mobile phone companies need to have
light at many different wavelengths. many …
- Some of the light they emit has very large
wavelengths (sometimes as long as a mile). These
5. Dangers: - Each color has a different wavelength.
- Prolonged exposure to microwaves is known to - Red has the longest wavelength and violet has the
cause “cataracts” in your eyes which is a clouding of shortest wavelength.
lens preventing you from seeing clearly (if at all!). So - When all the waves are seen together they make
don’t make a habit of pressing your face against the white light.
microwave oven door to see if your food’s ready! - When the white light shines through a prism or
- People work on aircraft carnet decks wears special through water vapour like the rainbow, the white
suits which reflect microwaves to avoid being light is broken apart into the colors of the visible
“cooked” by the powerful radar units in modern light spectrum.
military planes. - The light which our eyes can detect as part of the
visible spectrum (small).
INFRA-RED - There is a lot of radiation around us which is
- Infra-red waves are just below visible red light in the “invisible” in our eyes but can be detected by other
electromagnetic spectrum (“intra” means “below”). remote sensing? instruments and used to our
- You probably think of infra-red waves as heat advantage.
because they’re given off by hot objects and you can - The visible wavelengths cover a range from
feel them as warmth in your skin. approximately 0.4 to 0.77 mm (violet to red).
- Infra-red waves are also given off by stars, lamps,
flames and anything else that’s warm- including you.
Uses:
-Infra-red waves are called IR for short. They are used for
many tasks, for example, remote controls for TVs, and
video recorders and physiotherapists use heat lamps to
help heal sports injuries.
- Shorter, near infrared waves are not hot at all- in fact
you cannot even feel them. These shorter wavelengths RADIATION
are the ones used in your TV’s remote control.
Dangers:
The warmer the object, the more infrared radiation it - Too much light can damage the retina in your eye.
emits. - This can happen when you look at something very
bright, such as the sun.
- Because every object gives off IR waves, we can use
- Although the damage can heal, if it’s too bad, it’ll be
them “to see in the dark. Night sights for weapons
permanent.
sometimes use a sensitive IR detector.
- Gas infrared waves are thermal. In other words, we ULTRAVIOLET
experience the type of infrared radiation every day
in the form of heat! The heat that we feel from the -Ultra-violet
sunlight, a fire, a warm sidewalk are infrared. light is made by
- You’ve probably seen TV programmes in which the special lamps,
police helicopter track criminals at night using for example, on
cameras which can see in the dark. These cameras sun beds.
use IR instead of “ordinary light” which is why -It is also given
people look bright in pictures. off by the sun
in large
Dangers; quantities.
- The danger from too much infra-red radiation is very - We call it UV.
simple, overheating.
VISIBLE LIGHT Uses:
- Sun tan
- Visible light waves are the only electromagnetic - Detecting fake money
waves we can see. - Light sure composite
- We see these waves as the colors of the rainbow.
6. - UV in discos (glow in the dark) - The amount of energy carried by each quantum photon
- Sterilization depends on the frequency of the radiation.
- Sunlight (vitamin D) - If the frequency (vibrations per second) is doubled, the
The OZONE layer protects the earth from the heat of energy of the photon is doubled.
the sun. - The unit used to measure the energy of photons is the
Filters about 95% of heat. electron-volt (eV).
Only 5% heat UV reaches earth’s surface.
WHAT ARE X-RAYS?
Dangers: - X-rays are weightless packages of pure energy
- Sunburn- basal cell CA (photon) that have no electrical charge and travel in
- Cataract- blindness waves with specific frequency at a speed of 3 x 108
m/sec.
X-RAYS
- Their energies depend on the frequency of their
Uses:
wavelengths.
- MRI, CT-scan
- The greater the frequency of their wavelength, the
- Intra-oral x-rays
greater the energy of the photon.
- A drink of barium sulphate. This will absorb x-rays,
- The greater the energy of the photon, the more
and so the patient’s intestines will show up clearly
readily it will penetrate matter.
on an x-ray image
PROPERTIES OF X-RAYS
GAMMA RAYS
- X-rays are invisible and weightless; they cannot be
- They have the smallest wavelengths and the most
seen, felt or smelled.
energy of any other wave in the electromagnetic
- X-rays travel in straight lines, they can be deflected
spectrum.
from their original direction but the new trajectory is
- These waves are generated by radioactive atoms and
linear.
in nuclear explosions. 8.
- X-rays travel at the speed to light (3 x 10 ? m/sec).
- Gamma-rays can kill living cells, a fact which
- X-rays have a wide range of wavelengths, 0.01- 0.05
medicine uses to its advantage using gamma rays to
nm in length.
kills cancerous cells.
- X-rays cannot be focused to a point over distance
Radioactivity is particularly damaging to rapidly
the beam diverges much like a beam of light.
dividing cells, such as cancer cells.
- Because of their extremely hot wavelengths, they
This also explains why damage is done by
are able to penetrate materials that absorb and
radiotherapy to other rapidly dividing cells in
reflect visible light.
the body such as the stomach lining (hence
- X-rays cause certain substances to fluoresce, that is
nausea), hair follicles (hair tends to fall out) and
to emit radiation of longer wavelength (it is this
a growing fetus (not because of mutations, but
property that makes it possible to use intensifying
simply major damage to the baby’s rapidly
screens in radiography.
dividing cells).
- X-rays produce biological changes that are valuable
Dangers: in radiation therapy but necessitate caution when
- Gamma rays cause cell damage and can cause a used for diagnostic purposes.
variety of cancers. - X-rays can ionize gases that is remove electrons from
- Cause mutations in growing foetuses, so unborn atoms to form ions, which can be used for measuring
babies are especially vulnerable. the controlling exposure (ionization chambers).
PARTICLE CONCEPT OF ELECTROMAGNETIC RADIATION
-Short electromagnetic waves, such as x-rays, may react with
matter as if they were particles rather than waves.
- These particles are actually discrete bundles of energy
having no mass, and each of these bundles of energy is called
quantum or photon.
- These photon travel at the speed of light.