CREDIT HOURS:  3

Course Meeting Date/Times:  T/Th 9:50 a.m. – 11:35 a.m.

INSTRUCTOR:     Gary Gruenewald M.S., R.T(R)

PHONE:      708-237-5000  ext. 2825

EMAIL:       ggruenewald@nc.edu

COURSE DESCRIPTION:

This course introduces the student to basic x-radiation physics.  Areas covered in this course include:

units of radiation measurement, the physical concepts of energy, the structure of matter, and the

basic principles and nature of electricity and magnetism.

REQUIRED TEXTBOOKS:

Albany, New York

Bushong, Radiologic Science for Technologists, Ninth Edition, Mosby, St. Louis, MO

DeAngelis, The Integrated Radiography Workbook, Fourth Edition,

Health and Science Publishers, Rutland, VT

COURSE OBJECTIVES:

At the completion of the course, the student will be able to:

1.  understand the basic principles involved in the physical/electrical

2.  apply learned physical science knowledge to the understanding of

Units of Instruction

2. Radiographic Definitions and Mathematics Review
3. Fundamentals of the Physics of  Radiation Science
4. The Atom
5. Electromagnetic Energy
6. Electricity
7. Magnetism

COURSE OUTLINE:

I.             Basic Concepts of  Radiation Science

A.            Matter and Energy

1.             Matter and Mass

2.             Energy

1.             Natural Sources of Ionizing Radiation

2.             Medical X-Ray

II.            Radiographic Definitions and Mathematics Review

1.             Numeric Prefixes and Introduction to Exponential Notation

B.            Mathematics and Algebra Review

1.             Number Systems

2.             Algebra

3.             Graphing

III.          Fundamentals of the Physics of Radiation Science

A.            Units of Measurement

1.             Base Quantities and Derived Quantities

B.            Standards of Measurement

1.             Length

2.             Mass

3.             Time

C.            Systems of Measurement

1.             MKS, CGS, and British Systems

D.            Mechanics

1.             Velocity

2.             Acceleration

3.             Motion

4.             Weight

5.             Momentum

6.             Work

7.             Power

8.             Energy

9.             Kinetic Energy

10.          Heat

11.          Potential Energy

IV.          The Atom

A.            Centuries of Discovery

1.             Greek Atom

2.             Dalton Atom

3.             Thompson Atom

4.             Bohr Atom

B.            Combinations of Atoms

C.            Fundamental Particles

1.             Covalent Bonding

2.             Ionic Bonding

D.            Atomic Nomenclature

E.            Atomic Structure

1.             Electron Arrangement

A.            Photons

1.             Velocity and Amplitude

2.             Frequency and Wavelength

3.             Inverse Square Law

B.            Electromagnetic Spectrum

1.             Visible Light

C.            Wave-Particle Duality

1.             Wave Model: Visible Light

2.             Particle Model:     Quantum Theory

D.            Matter and Energy Review

VI.          Electricity

A.            Electricity

B.            Electrostatics

1.             Units of Electric Charge

2.             Electrification

3.             Electrostatic Laws

4.             Electric Potential (Volt)

C.            Electrodynamics

1.             Conductors and Insulators

2.             Electric Circuits

3.             Direct Current and Alternating Current

4.             Electric Power

VII.         Magnetism

A.            History of Naturally Occurring Magnetic Materials

B.            Introduction to Magnetism

C.            Classification of Magnets

D.            Magnetic Laws

1.             Dipoles

2.             Attraction and Repulsion

3.             Magnetic Induction

4.             Magnetic Force

UNIT OBJECTIVES

Unit I - Basic Concepts of Radiation Science

At the completion of this unit, the student will be able to:

1.             Identify the difference between matter and energy.

3.             Explain how x-rays were discovered.

4.             Discuss human injury caused by radiation.

5.             List basic radiation protection equipment.

6.             Describe a brief history of modern radiography and discuss what behaviors are required of a radiographer.

Unit II -  Radiographic Definitions and Mathematics Review

At the completion of this unit, the student will be able:

1.             Accurately  utilize scientific exponential notation and the associated prefixes.

2.             List and define units of radiation measurement and absorbed dose.

3.             Calculate problems using fractions, exponents, and algebraic equations.

Unit III - Fundamentals of the Physics of  Radiation  Science

At the completion of this unit, the student will be able to:

1.             Discuss the derivation of scientific systems of measurement.

2.             List the systems of measurement.

3.             Identify nine categories of mechanics and recite/utilize their associated formulas.

Unit IV  -  The Atom

At the completion of this unit, the student will be able to:

1.             Relate the history of the atom from as early as 200 B.C.

2.             Identify the structure of an atom.

3.             Describe electron shells and instability within atomic structure.

4.             Discuss radioactivity and the characteristics of alpha and beta particles that can ionize matter.

5.             Explain the difference between two forms of ionizing radiation - particulate and electromagnetic.

At the completion of this unit, the student will be able to:

1.             Identify the properties of photons.

2.             Explain the inverse square law.

3.             Define wave theory and quantum theory.

4.             Discuss the electromagnetic spectrum.

Unit VI - Electricity

At the completion of this unit, the student will be able to:

1.             Identify the electric charges of photons and electrons.

2.             Define electrification and state examples.

3.             List the laws of electrostatics.

4.             Name examples of conductors and insulators.

5.             Describe electric circuits and recognize circuit element symbols.

6.             Define direct and alternating current.

7.             Identify units of electric potential and electric power.

Unit VII - Magnetism

At the completion of this unit, the student will be able to:

1.             Discuss the history and discovery of naturally occurring magnetic materials.

2.             Define magnetic dipole.

3.             List the various classifications of magnets.

4.             Identify the interactions between matter and magnetic fields.

5.             List and discuss the four laws of magnetism.

UNIT 1  -  Concepts of Radiologic Science

Bushong Chapter 1 - Powerpoint Slide Notes:

Basic Definitions:

Matter:  anything that occupies space and has mass

-   The fundamental building blocks of matter are atoms.

Mass:  the quantity of matter contained in any physical object

-The term weight is generally used when describing the mass of an

object.

-    weight is the force exerted on a body under the influence of gravity

Mass is measured in kilograms.

Weight is measured using a unit called the Newton.

Weight is determined by the gravitational force exerted on a body.

As an example, a student having a mass of 75 kilograms would weight 735 Newtons on the Earth but weight only 120 Newtons on the moon.

Energy is the ability to do work.

In the International System of Measurement (SI), energy is measured in joules (J).

Potential Energy – the ability to do work by virtue of position

Kinetic Energy – the energy of motion

Chemical Energy – the energy released by a chemical reaction

Electrical Energy – the work that can be done when an electron moves through an electrical potential difference

Thermal Energy – the energy of motion at the atomic/molecular level – closely related to temperature

Nuclear Energy – energy contained in the nucleus of an atom

Electromagnetic Energy -  includes cosmic rays, gamma rays, x-rays, ultraviolet light, visible light,

infrared light, radar, microwaves, TV, radio, cell phones and all electronic transmission systems.

Electromagnetic radiation is made up of electric and magnetic fields that move at right angles to each other at the speed of light.

Matter and energy are interchangable.

Energy emitted and transferred through space is called radiation.

Ionizing radiation is any kind of radiation capable of removing an orbital electron from the atom with which it interacts.

The orbital electron and the atom from which it was separated are called an ion pair.

Sources of Ionization

•  X-rays
•  Gamma Rays
•  Ultraviolet Light
•  Fast moving particles, Alpha Particles, Beta Particles

The x-ray was discovered (not invented) by Wilhelm Conrad Roentgen quite by accident.

Review Facts:

- November 8, 1895
- University of Wurzburg, Germany
- working with a Crooke’s Tube
- Plate coated with barium platinocyanide began to glow
- “X” was for the unknown

Through the use of the scientific method, Roentgen found that x-rays (are):

highly penetrating, invisible rays which are a form of electromagnetic radiation.

electrically neutral and therefore not affected by either electric or magnetic fields.

polyenergetic and heterogeneous.

release small amounts of heat when passing through matter.

travel in straight lines.

travel at the speed of light.

can ionize matter.

can cause fluorescence of certain crystals.

cannot be focused by a lens.

affect photographic paper.

can produce chemical and biologic changes in matter through ionization and excitation

An X-Ray beam satisfactory for imaging requires:

Thousands of volts of electricity – kilovoltage

Thousandths of an ampere of electricity – milliamperage

Today, the hand can be imaged in milliseconds (thousandths of a second).

In the early days of radiography, it often took several minutes to image the hand!

Image blur, due to motion, was a huge problem in radiography’s early days.

Imaging times were shortened with the development of the intensifying screen and double-emulsion radiography.

The fluoroscope was developed in 1898, by the American inventor, Thomas Alva Edison.

He eventually stopped his work in radiology after his assistant, Clarence Dally, became the first x-ray fatality in the United States.

Today we know low doses may result in a small incidence of latent harmful effects.

It is well established that a fetus is most sensitive to the effects of radiation exposure within the first trimester.

Although effective radiation safety practices make for a safe working environment today, never become complacent

Always practice ALARA and utilize the cardinal principles of:

- Time
- Distance
- Shielding

Filtration –removes low energy photons from beam

Intensifying Screens – allow for decreased exposure

Gonadal Shields – protect reproductive organs

Protective Barriers -  i.e. control booth

Except for screening mammography, examination of asymptomatic patients is not indicated.

The benefits of any radiologic procedure must always outweigh the risks.

Powerpoint Notes:  Carlton - Radiation Concepts

Radiography is the recording of images created by the use of x-ray energy.

Radiography is both an art and a science.

Science  -  the use of knowledge in an organized and classified manner.

Natural Science  -  the study of the universe and its contents.

-  can be divided into two categories

1.  physical science

2.  biological science

Physics  -  a branch of physical science that studies matter and their interrelationships.

Definitions

Matter  - the substance that comprises all physical objects

-  it has shape, form and occupies space

Mass  -  the quantity of matter contained in any physical object

-  the unit of mass is the kilogram

Weight – the force that an object exerts under the influence of gravity

-  the unit of weight is the Newton

Substance  -  a material that has definite and constant composition

Mixture  -  the combination of two or more substances

Substances may be either simple or complex.

Simple substances  =  elements

Complex substances  =  compounds

An element is a substance that cannot be broken down into any simpler substance by ordinary means.

There are 92 naturally occurring elements.

When two or more elements are chemically united in definite proportion, compounds are formed.

Energy is the ability to do work.

Energy emitted and transferred through matter is called radiation.

Albert Einstein, in 1905, described the unique relationship between matter and energy.

According to Einstein, matter and energy are interchangeable.

The basis of Einstein’s work is the Law of Conservation of Energy

- matter and

Atoms can be divided into three basic subatomic particles.

Protons – positively charged and located in the atom’s nucleus

Neutrons – no charge and located in the atom’s nucleus

Electrons – negatively charged and located in shells surrounding the nucleus

energy cannot be created or destroyed  but can be converted from one form to another.

In 1913, Neils Bohr, a Danish physicist, proposed a model of the atom which is

likened to the solar system.

Center = nucleus (Sun)

Orbits = electrons (planets)

This model is still widely used today.

Protons and neutrons together are called nucleons.  They are located in the atom’s nucleus.

Electrons are located outside of the nucleus and have a relatively insignificant

mass compared to the nucleons.

Electrons cannot be divided into smaller parts, but protons and neutrons can be

divided into subnuclear structures called quarks.

The number of protons in the nucleus is known as the atomic number or Z number.

The atomic number gives an atom its identity (the type of element it is an atom of).

If an atom gains or loses a proton, it becomes an atom of a different element!

The number of both protons and neutrons in the nucleus determine an atom’s mass number or A number.

The mass of the particles of an atom is sometimes described in atomic mass units

In science this is more exact than simply stating the mass number.

An atom that loses or gains a neutron is called an isotope.

An atom that gains or loses an electron is called an ion.

The distance from the nucleus determines the energy level or shell the electon occupies.

Each shell has a certain amount of binding energy (measured in eV) which holds it in its orbit

around the nucleus.  The closer an electron is to the nucleus, the greater is its binding energy.

The shell closest to the atom’s nucleus is the  K shell, next is the L shell, then the M shell.

The shell number is referred to as the principle quantum number.

K shell = 1  L shell = 2  etc.

In a neutral atom, the number of electrons equals the number of protons.

The maximum number of electrons that can occupy a given shell is defined by the formula:

2(N)^2

The Octet Rule – The number of electrons in the outermost shell never exceeds eight electrons.

Atoms are most stable if they have a filled outer shell.  Atoms may gain or lose (ionic compounds) or

share (covalent compounds) electrons to achieve this stability.

The periodic "law" of chemistry recognizes that properties of the chemical elements are periodic

functions of their atomic number (that is, the number of protons within the element's atomic nucleus).

The periodic table is an arrangement of the chemical elements ordered by atomic number in columns

(groups) and rows (periods) presented so as to emphasize their periodic properties.

During the mid-1800’s, a Russian scientist Dmitri Mendeleev (1834 – 1907), developed the first

periodic table of the elements.

The elements are arranged in increasing order of atomic number (Z) as you go from left to right

across the table. The horizontal rows a called periods and the vertical rows, groups.

A noble gas is found at the right hand side of each period. There is a progression from metals to

non-metals across each period. Elements found in groups (e.g. alkali, halogens) have a similar

electronic configuration. The number of electrons in outer shell is the same as the number of the

group (e.g. lithium 2·1).
The block of elements between groups II and III are called transition metals.

They are often used as catalysts. Elements 58 to 71 are known as lanthanide or rare earth elements.

These elements are found on earth in only very small amounts.

Elements 90 to 103 are known as the actinide elements. They include most of the well known elements

which are found in nuclear reactions. The elements with larger atomic numbers than 92 do not occur naturally.

They have all been produced artificially by bombarding other elements with particles.

The number of electrons in the outermost shell determines the chemical combining

characteristics or valence of the element.

Electromagnetic radiation (EM) spans a continuum of wide ranges of magnitudes of energy.

All waves of energy encompassed in the electromagnetic spectrum travel at the speed of light.

Electromagnetic energy travels through space in the form of waves.

The distance between any two successive points on a wave is termed wavelength.

It is represented by the Greek letter lambda.

Wavelengths vary from kilometers to angstroms (A)

1 angstrom = 1.0 × 10^-10 meters .

X-rays = .1 to .5 angstroms

The frequency is the number of waves that passes a particular point in a given time frame.

It is represented by the Greek letter nu.

Wave/particle duality is the possession by physical entities (such as light, x-rays and electrons) of

both wavelike and particle-like characteristics. On the basis of experimental evidence, the German

physicist Albert Einstein first showed (1905) that light, which had been considered a form of electromagnetic

waves, must also be thought of as particle-like, or localized packets of discrete energy (photons).

Photon energy and frequency are directly related.

­Increase  Frequency   =  Increase­  Energy

Through his use of the scientific method, Roentgen found that x-rays:

•  are highly penetrating, invisible rays which are a form of electromagnetic radiation.
•  are electrically neutral.
•  are polyenergetic and heterogeneous.
•  release small amounts of heat when passing through matter.
•  travel in straight lines.
•  travel at the speed of light.
•  can ionize matter.
•  can fluorescence certain crystals.
•  cannot be focused by a lens.
•  affect photographic film.
•  produce chemical and biologic changes in matter.
•  produce secondary and scatter radiation.

Powerpoint Notes:  Fundamentals of Radiologic Science

Objectives:

At the completion of this unit, the student will be able to:

•Discuss various scientific systems of measurement
•List three systems of measurement
•Identify the nine categories of mechanics

There are various categories of “Physics”.

In radiography, however, physics is principally limited to the study of two:

1.Mechanics
2.Electromagnetism

Physicists strive for certainty and simplicity when experimenting and drawing conclusions.

In mechanics – there are only three measurable base quantities:

-Mass
-Length
-Time

Combinations of the base quantities form the derived quantities :

•Energy
•Work
•Power
•Momentum
•Force
•Velocity

Special quantities of measurement exist in various areas of science.  In radiology, these include:

•Exposure
•Dose
•Dose Equivalent
•Acceleration

Mass:

Unit of Mass = Kilogram

Defined as the mass of 1000 cubed centimeters of water at 4 degrees Celsius.

The prototype of the kilogram is also in Paris, at the International Bureau of Weights and Measures.

Length:

Unit of length = Meter

Originally defined by the distance between two engraved lines on a platinum-iridium bar kept at the International Bureau of Weights and Measures in Paris, France.

The international standard unit of length, termed the meter, is approximately equivalent to 39.37 inches. The meter was redefined, in 1983, as the distance traveled by light in a vacuum in 1/299,792,458 of a second.

Time:

Unit of time = Second

Originally defined in term’s of the Earth’s rotation – a fraction of a mean solar day –, it is now based on the vibration of cesium atoms in an atomic clock.

Every measurement has two parts :

1. Magnitude
2. Unit

i.e.  100 centimeters

Four Systems Used to Represent the Base Quantities

1. MKS – meter, kilometer, second
2. CGS – centimeter, gram, second
3. SI – meter, kilometer, second + derived quantities
4. British – Foot, Pound, Second

Mechanics:

A segment of physics which deals with objects at rest and objects in motion.

Velocity:

Sometimes called speed – it describes how fast an object is moving.

Precise Definition – the rate of an object’s change of position with time.

Unit = m/s

d

V  = _______

t

Average Velocity:

initial velocity  +  final velocity

V  =     _____________________________

2

Acceleration:

Describes how quickly or slowly the velocity is changing.

Unit = m/s^2

v (final)     -    v(initial)

a =         _______________________

t

Newton's First Law of Motion:

A body will remain at rest or continue to move with constant velocity in a straight line unless acted on by an external force.

Newton's Second Law of Motion:

The force (F) acting on an object with acceleration (a) is equal to the mass (m) multiplied by acceleration.

Newton's Third Law of Motion:

For every action there is an equal and opposite reaction.

Weight:

A force on a body caused by the downward pull of gravity on it.

Wt = mg

Acceleration of gravity:

Because mass affects both the force of gravity and the resistance to accelerate, all objects end up falling at the same rate.

Gravity on Earth:

At our distance from the Earth's center, using the mass of the Earth, we get an acceleration of 9.8 m/s^2.

Momentum (p)

The product of the mass of an object and its velocity is called momentum, represented by p.

p = mv

The greater the velocity or mass an object has, the greater is its momentum.

Law of Conservation of Momemtum:

The total momentum before any interaction is equal to the total momentum after the interaction.

Work:

The work done  on an object is the force applied multiplied by the distance over which it is applied.

W = Fd

The unit of work is the Joule (J)

Power:

Power is the rate of doing work.

P = Work/t

-or-

P=Fd/t

The unit is the

J/s also called the watt(W)

British unit = horsepower (hp)

1 hp = 746 watts

1000 W = 1 kilowatt

Heat:

The kinetic energy of the random motion of molecules

The more rapid and disordered the motion of molecules, the more heat an object contains.

The unit of heat, the calorie is defined as the heat necessary to raise the temperature of 1 gram of water through 1 degree Celsius.

With a library of over 2,600 videos covering everything from arithmetic to physics, finance, and history and 253 practice exercises, we're on a mission to help you learn what you want, when you want, at your own pace.

Newton's First law of Motion:

Newton's Second Law of Motion:

Would a Brick or Feather Fall Faster:

Newton's Third Law of Motion:

Introduction to Gravity:

Acceleration:

Momentum:

Numerator and Denominator:

Multiplying Fractions:

Dividing Fractions Example:

Converting Fractions to Decimals:

Understanding Proportions:

Find an Unknown in a Proportion:

Exponent Rules:

Interpreting Linear Graphs:

Scientific Notation:

Order of Operation:

Significant Figures (Digits):

POWERPOINT  -  Carlton - Chapter 2

Radiography is the recording of images created by the use of x-ray energy.

Radiography is both an art and a science.

Science  -  the use of knowledge in an organized and classified manner.

Natural Science  -  the study of the universe and its contents.

-  can be divided into two categories

1.  physical science

2.  biological science

Physics  -  a branch of physical science that studies matter and their interrelationships.

Definitions

Matter  - the substance that comprises all physical objects

-  it has shape, form and occupies space

Mass  -  the quantity of matter contained in any physical object

-  the unit of mass is the kilogram

Weight – the force that an object exerts under the influence of gravity

-  the unit of weight is the Newton

Substance  -  a material that has definite and constant composition

Mixture  -  the combination of two or more substances

Substances may be either simple or complex.

Simple substances  =  elements

Complex substances  =  compounds

An element is a substance that cannot be broken down into any simpler substance by ordinary means.

There are 92 naturally occurring elements.

When two or more elements are chemically united in definite proportion, compounds are formed

An atom is the smallest particle of an element.

A molecule is formed by two or more atoms which are chemically united.  A molecule is the smallest

component of a compound.

The degree of attraction between atoms and molecules determines if the substance is a solid, liquid or gas.

Weak attraction = gas

Strong attraction = solid

Energy is the ability to do work.

Energy emitted and transferred through matter is called radiation.

Albert Einstein, in 1905, described the unique relationship between matter and energy.

According to Einstein, matter and energy are interchangeable.

The basis of Einstein’s work is the Law of Conservation of Energy  -  matter and energy cannot be

created or destroyed  but can be converted from one form to another.

Atoms can be divided into three basic subatomic particles.

Protons – positively charged and located in the atom’s nucleus

Neutrons – no charge and located in the atom’s nucleus

Electrons – negatively charged and located in shells surrounding the nucleus

In 1913, Neils Bohr, a Danish physicist, proposed a model of the atom which is likened to the solar system.

Center = nucleus (Sun)

Orbits = electrons (planets)

This model is still widely used today.

Protons and neutrons together are called nucleons.  They are located in the atom’s nucleus.

Electrons are located outside of the nucleus and have a relatively insignificant mass compared to the nucleons.

Electrons cannot be divided into smaller parts, but protons and neutrons can be divided into subnuclear structures called quarks.

The number of protons in the nucleus is known as the atomic number or Z number.

The atomic number gives an atom its identity (the type of element it is an atom of).

If an atom gains or loses a proton, it becomes an atom of a different element!

The number of both protons and neutrons in the nucleus determine an atom’s mass number or A number.

The mass of the particles of an atom is sometimes described in atomic mass units

In science this is more exact than simply stating the mass number.

An atom that loses or gains a neutron is called an isotope.

An atom that gains or loses an electron is called an ion.

The distance from the nucleus determines the energy level or shell the electon occupies.

Each shell has a certain amount of binding energy (measured in eV) which holds it in its orbit around

the nucleus.

The closer an electron is to the nucleus, the greater is its binding energy.

The shell closest to the atom’s nucleus is the  K shell, next is the L shell, then the M shell.

The shell number is referred to as the principle quantum number.

K shell = 1  L shell = 2  etc.

In a neutral atom, the number of electrons equals the number of protons.

The maximum number of electrons that can occupy a given shell is defined by the formula:

2(N)^2

The Octet Rule – The number of electrons in the outermost shell never exceeds eight electrons.

Atoms are most stable if they have a filled outer shell.  Atoms may gain or lose (ionic compounds)

or share (covalent compounds) electrons to achieve this stability.

The noble gases are found in group 18 of the periodic table.

All noble gases have the maximum number of electrons possible in their outer shell

(2 for Helium, 8 for all others), making them stable. The noble gasses are described as being inert.

The periodic "law" of chemistry recognizes that properties of the chemical elements are periodic

functions of their atomic number (that is, the number of protons within the element's atomic nucleus).

The periodic table is an arrangement of the chemical elements ordered by atomic number in columns (groups)
and rows (periods) presented so as to emphasize their periodic properties.

During the mid-1800’s, a Russian scientist Dmitri Mendeleev (1834 – 1907),

developed the first periodic table of the elements.

While attempting to organize the elements according to their chemical properties and atomic weight,

Dmitri Mendeleyev developed the Periodic Table and formulated the periodic law.

His classification revealed recurring patterns (periods). Because of this, he left spaces in

his table for elements that he correctly predicted would be discovered. His forward-thinking

attitude extended into his politics as well as his classroom. Mendeleyev was a popular but controversial professor.

Periodic Table:  The elements are arranged in increasing order of atomic number (Z)

as you go from left to right across the table. The horizontal rows a called periods

and the vertical rows, groups.

A noble gas is found at the right hand side of each period. There is a progression from

metals to non-metals across each period. Elements found in groups (e.g. alkali, halogens)

have a similar electronic configuration. The number of electrons in outer shell is

the same as the number of the group (e.g. lithium 2·1).

The block of elements between groups II and III are called transition metals.

They are often used as catalysts. Elements 58 to 71 are known as lanthanide or

rare earth elements. These elements are found on earth in only very small amounts.

Elements 90 to 103 are known as the actinide elements. They include most of the

well known elements which are found in nuclear reactions. The elements with larger

atomic numbers than 92 do not occur naturally. They have all been produced artificially

by bombarding other elements with particles.

The number of electrons in the outermost shell determines the chemical

combining characteristics or valence of the element.

Electromagnetic radiation (EM) spans a continuum of wide ranges of magnitudes of energy.

All waves of energy encompassed in the electromagnetic spectrum travel at the speed of light.

Electromagnetic energy travels through space in the form of waves.

The distance between any two successive points on a wave is termed wavelength.

It is represented by the Greek letter lambda.

Wavelengths vary from kilometers to angstroms (A)

1 angstrom = 1.0 × 10^-10 meters .

X-rays = .1 to .5 angstroms

The frequency is the number of waves that passes a particular point

in a given time frame.  It is represented by the Greek letter nu.

Wave/particle duality is the possession by physical entities (such as light, x-rays and electrons)

of both wavelike and particle-like characteristics. On the basis of experimental evidence,

the German physicist Albert Einstein first showed (1905) that light, which had been

considered a form of electromagnetic waves, must also be thought of as particle-like,

or localized packets of discrete energy (photons).

Photon energy and frequency are directly related.

­Discovery of the X-Ray

November 8,1895 – Roentgen discovers x-ray accidentally while working with a

Crookes tube – University of Wurzburg, Germany

1901-  Roentgen receives the first Nobel Prize in physics

Through his use of the scientific method, Roentgen found that x-rays:
•  are highly penetrating, invisible rays which are a form of electromagnetic radiation.
•  are electrically neutral.
•  are polyenergetic and heterogeneous.
•  release small amounts of heat when passing through matter.
•  travel in straight lines.
•  travel at the speed of light.
•  can ionize matter.
•  can fluorescence certain crystals.
•  cannot be focused by a lens.
•  affect photographic film.
•  produce chemical and biologic changes in matter.
•  produce secondary and scatter radiation.

Scalars and Vectors

Physics is a mathematical science - that is, the underlying concepts and principles have a mathematical basis.

The motion of objects can be described by words - words such as distance, displacement, speed, velocity, and acceleration.

These mathematical quantities which are used to describe the motion of objects can be divided into two categories.

The quantity is either a vector or a scalar. These two categories can be distinguished from one another

by their distinct definitions:

• Scalars are quantities which are fully described by a magnitude alone.
• Vectors are quantities which are fully described by both a magnitude and a direction.

Examples:

5 m  -  scalar

30 m/sec, East  -  vector

5 mi., North  -  vector

10 kilometers  -  scalar

http://www.howstuffworks.com/atom.htm  Link to How Stuff Works - How Atoms Work

The Structure of Matter - Powerpoint

The ancient Greeks believed all matter was composed of four substances -

earth, water, air and fire.

The term atom comes from the Greeks and translates to “indivisible.  They believed that the smallest

division of earth, air, fire and water was an “atom”.

This concept of the atom persisted until an English school teacher, John Dalton, in the early 1800s,

challenged the Greek understanding of the atom.

Dalton believed that all atoms of a given element were basically the same and that they combined with

other elements based on the type and number of “eyes and hooks” each of them had.  As they joined,

new compounds were formed.

Fifty years after Dalton’s work, a Russian scholar, Dimitri Mendeleev, developed the first periodic table

of the elements.  In his table he arranged the elements in order of ascending atomic mass and on the

basis of the repetition of similar chemical properties.

In the late 1890s a scientist by the name of  J.J. Thomsom discovered that electrons played an

integral role in keeping atoms together. He received the Noble Prize in Physics in 1906 for his discovery

of the electron.  Thomson’s model of the atom is often described as a plum pudding with the plums representing the electrons.

In 1911, Ernest Rutherford developed a model of the atom that had a dense small area in the middle that was positively

charged (the nucleus) and was surrounded by electrons.

In 1913, Neils Bohr, a Danish physicist, expanded on Rutherford’s work.  His model of the atom was likened

to a miniature solar system.  Bohr’s model is still used today.

Nucleons – protons and neutrons – are composed of quarks that are held together by gluons.

The fundamental atomic particles are the electron, the proton and the neutron.

Protons and neutrons have nearly 2000 times the mass of an electron.

The atom is mostly empty space.

The nucleus is small, but contains the majority of the atom’s mass.

An atom’s electrons are located at specific distances from the nucleus in defined orbits termed shells.

The formula used to find the maximum number of electrons that may occupy a given shell is 2 n squared

where n is equal to the shell number (i.e. k=1, l=2, etc.)

Shell number (n)  =  principal quantum number

Electrons are held in their respective orbits via a balance between centripetal and centrifugal forces.

The strength of attachment of an electron to the nucleus is termed the electron’s binding energy.

The closer an electron is to the nucleus, the greater is its binding energy.

The larger and more complex the atom, the higher will be the electron binding energy in any given shell.

Because electrons of atoms with many protons are more tightly bound to the nucleus than those of

small atoms, it generally takes more energy to ionize a large atom than a small atom.

The outermost shell of an atom can never exceed eight electrons.

The octet rule says that atoms tend to gain, lose or share electrons so as to have eight

electrons in their outer electron shell.

Elements with the maximum number of electrons already in their outermost shell are termed the noble gases.

In an atom, the number of protons (positive charges) exactly equals the number of electrons (negative charges).

In an ion, there is an unequal number of protons (positive charges) and electrons (negative charges).

An atom’s identity is defined by the number of protons in its nucleus.  This is known as the Z or atomic number.

The number of neutrons plus the number of protons is the atom’s A or mass number.

In all but the lightest atoms, the number of neutrons is always greater than the number of protons.

The larger the atom, the greater the abundance of neutrons over protons.

Isotopes of an element have nuclei with the same number of protons (the same atomic number)

but different numbers of neutrons. Therefore, isotopes have different mass numbers,

—the number of protons plus neutrons.

Isotope  -  Atoms that have the same atomic number, but different atomic mass numbers.

Isobar – nuclei that have the same atomic mass number but different atomic numbers.

Isotone  -  atoms having the same number of neutrons but different numbers of protons.

Isomer  -  atoms having the same atomic number and the same mass number. They are different excited states

of the same type of nucleus.

Molecules   -  Atoms of various elements may combine to form structures called molecules.

Compound  -  any quantity of one type of  molecule

Atoms join to form molecules either by ionic or covalent bonds.

Radioactivity  -  the emission of particles and energy in order for an unstable atom to become stable.

Radioactive decay results in the emission of alpha particles, beta particles and usually gamma rays.

Alpha Particle Emission -

A violent decay process whereby a very unstable nucleus emits an alpha particle (2 protons + 2 neutrons).

The atom loses two units of positive charge and four units of mass.

Beta Particle Emission -

During beta emission an electron is created in the nucleus and is emitted.  The electron is created during

a conversion of a neutron into a proton.  During beta emission, the atomic number increases by one while

the atomic mass number remains the same.

Alpha particles having a +2 charge, are very ionizing and have a range of approximately 1 - 10 cm. in air.

They can actually be stopped by a sheet of paper.  Beta particles have a -1 charge, have a range of up to

10 meters in air and can be stopped by a sheet of wood.  Gamma rays are very penetrating, having a range

of many meters in air.  They have no charge and therefore it takes thick concrete or lead to stop these rays.

Basically, the only difference between beta particles and electrons is their origin.  Electrons exist in shells

around the nucleus and beta particles come from the nucleus of a radioisotope.

The only difference between x-rays and gamma rays is their origin also.  Gamma rays are emitted from the

nucleus of a radioisotope while x-rays are produced outside of the nucleus.

Some radioisotopes are pure beta emitters or pure alpha emitters.  Most emit gamma radiation

simultaneously with the particle emission.

The radioactive half-life for a given radioisotope is the time for half the radioactive nuclei in any sample

to undergo radioactive decay. After two half-lives, there will be one fourth the original sample, after three

half-lives one eight the original sample, and so forth.  Theoretically, the quantity of radioactive material

never quite reaches zero.

The concept of half-life is essential to radiology.  It is used daily in nuclear medicine and has an exact parallel

in x-ray terminology, the half value layer.

Carbon 14 Dating -

In simplified terms, here is how it works:  Carbon, what we see in charcoal and charred wood, comes in

many different forms.  The most common is Carbon-12 (C-12).  Carbon-14 (C-14) is a radioactive form of

carbon and is much rarer.  There are about a trillion C-12 atoms to one C-14 atom in living things.  C-14 is

formed in the atmosphere by cosmic rays.  Plants and animals in their interaction with the atmosphere naturally

absorb C-14 just like they do C-12.  Thus, a consistent ratio of C-12/C-14 exists in all living things.  That is,

at least, until they die and no longer absorb carbon from the atmosphere.  Scientists can then measure the

ratio in a dead organism and tell how long it has been dead.

X-Rays and gamma rays exist at the speed of light or not at all.

Equipped with his five senses, man explores the universe around him and calls the adventure Science.

~Edwin Powell Hubble, The Nature of Science, 1954

Video on Fission and Fusion:   http://www.youtube.com/watch?v=yTkojROg-t8

Video on how nuclear reactors work:  http://www.youtube.com/watch?v=VJfIbBDR3e8

Electromagnetic Energy

Video  -  Introduction to Waves  -  Khan Academy

Video  -  Amplitude, Frequency, Period and Wavelength of Periodic Waves  -  Khan Academy

A photon is the smallest quantity of any type of electromagnetic radiation.  A photon is sometimes referred to as a

quantum, or small bundle of energy traveling through space at the speed of light.

James Clerk Maxwell's electromagnetic wave theory was one of the crowning achievements of 19th century

physics.  The theory suggested that light waves have both electric and magnetic properties – hence electromagnetic radiation.

Photons, being part of the electromagnetic spectrum, all travel at the speed of light.

Wave Properties

Amplitude = ½ the range from crest to valley

Wavelength = the distance between two corresponding points on a wave

Frequency = the number of wavelengths passing a point of observation per second

The unit of frequency is the hertz.

One hertz is equal to one cycle per second.

The hertz is named after the German physicist Heinrich Rudolf Hertz,

who made important scientific contributions to electromagnetism.

At a given velocity, wavelength and frequency are inversely proportional.

The electromagnetic spectrum includes the entire range of electromagnetic radiation.

The known electromagnetic spectrum has three regions most important to radiologic technology –

The energy of a photon is directly proportional to its frequency.

When white light is refracted, it emerges in the distinct colors that compose it.

The prism acts to separate the emerging light into colors of various wavelengths.

Visible light occupies the smallest segment of the electromagnetic spectrum.

Communication broadcasts are usually identified by their frequency of transmission and are called

Radiation having sufficient energy to dislodge electrons from their orbit is termed ionizing radiation.

Particulate Radiation = Alpha and Beta

- Part of the Electromagnetic Spectrum

A part of the electromagnetic spectrum

The only difference between x-rays and gamma rays is their origin.

In physics and chemistry, wave–particle duality is the concept that all matter exhibits both

wave-like and particle-like properties. A central concept of quantum mechanics, duality addresses

the inadequacy of classical concepts like "particle" and "wave" in fully describing the behavior of objects.

The idea of duality is rooted in a debate over the nature of light and matter dating back to the 1600s,

when competing theories of light were proposed by Christiaan Huygens and Isaac Newton.

Through the work of Albert Einstein, Louis de Broglie and many others, current scientific theory holds

that all particles also have a wave nature.

Light striking an object causes orbital electrons of the object to become excited to a higher energy level.

The excess energy is immediately reemitted as another photon of light.  The light is said to be reflected.

There are three degrees of interaction between light and an absorbing material: transparency, translucency and opacity.

Glass may be transparent which means that light can be transmitted through it almost entirely unaltered.

The surface is smooth and the molecular structure is tight and orderly.  Incident light waves cause molecular

and electronic vibrations within the glass. These vibrations are transmitted through the glass and re-irradiated almost without change.

Glass can be made translucent by roughing up its surface.  Light is still transmitted but it is scattered and reduced

in intensity.  Instead of seeing images through it clearly, the images are blurred.

Glass can be made opaque by painting it black.  The characteristics of the paint’s pigment absorbs any

light that would otherwise pass through the glass.

Similar terms are used in radiography to describe the appearance of structures on the radiograph.

Structures that absorb x-rays are termed radiopaque and structures that allow x-rays to penetrate are  radiolucent.

 Type of X-Ray Diffraction     <10 kVp Grenz Rays     10-20 kVp Superficial    50-100 kVp Diagnostic   30-150 kVp Orthovoltage  200-300 kVp Supervoltage  300-1000 kVp Megavoltage  >1 MeV

X-Rays are created at the speed of light (c) and either exist at that velocity or do not exist at all.

This is one of the substantive statements of Plank’s Quantum Theory.  He also stated that photon

energy is directly proportional to photon frequency.

Mathematically the relationship between energy and frequency is expressed by the formula:

E = hf.

The Law of Conservation of Energy states that energy cannot be created or destroyed, but can change its form.

The Law of Conservation of Matter states that during an ordinary chemical change, there is no detectable

increase or decrease in the quantity of matter.

According to classic physics, the total quantity of matter and energy available in the

universe is a fixed amount and never any more or less.

Planck and Einstein, through their work, affirmed the above statements.  Einstein, in his Theory of Relativity,

sought, via his famous equation, to describe the true relationship between matter and energy.

Energy = mass x speed of light squared

Unit  -  Electricity, Magnetism and Electromagnetism

Video:  Electric Potential Energy - http://www.khanacademy.org/video/electric-potential-energy?playlist=Physics

Video: Electricity and Circuits - http://www.youtube.com/watch?v=D2monVkCkX4

1 Coulomb =

6,300,000,000,000,000,000 electrons

(6.3 x 10^8   electrons)

Electrification via    1.    Contact

2.    Friction

3.    Induction

Laws of Electrostatics

• Unlike charges attract, like charges repel
• Electrostatic force is directly proportional to the product of the charges and inversely proportional to the square of the distance between them
• When an object becomes electrified, the electric charges are distributed throughout the object or on its surface
• Electric charges are concentrated along the sharpest curvature of the surface

Voltage   =  Electromotive Force

increase­ voltage,  ­ increase the potential to do work

PowerPoint  -  Electricity and Magnetism

At the completion of this unit, the student will be able to:

1.Define electrification and provide examples.
2.List the laws of electrostatics
3.Define direct current and alternating current.
4.Identify units of electric potential and electric power.
5.Define magnetic dipole.
6.Identify the interactions between matter and magnetic fields.
7.Discuss the four laws of magnetism.

Electrostatics is the study of stationary electric charges.

Electric charges are either positive or negative.

Electrons and protons are the smallest units of electric charge.

Protons have a +1 charge and electrons have a -1 charge.

Electrons are more freely movable than protons within an atom. Therefore, nearly all discussions of electric charge deal

with electrons (negative electric charges).

An object is said to be electrified if it has too few or too many electrons.

Electrification can be created by contact, friction or induction.

Electrification is due to the movement of negative electric charges.

Positive electric charges do not move.

A transfer of electrons from one object to another causes the first to be positively electrified and

the second to be negatively electrified.

An object that is always available to accept electric charges from an electrified object is the Earth.

It behaves as a huge reservoir for stray electric charges and is electrically speaking referred to as electric ground.

A dramatic example of the movement of electrons can be seen during a thunderstorm.

The smallest unit of electric charge is the electron.  Because this single charge is difficult to measure, a

quantity of electrons termed a coulomb (C) is the fundamental unit of electric charge.

The coulomb is the standard unit of electric charge in the International System of Units (SI).

A quantity of 1 C is equal to approximately 6.24 x 10^18, or 6.24 quintillion electron charges.

Four laws describe how electric charges interact with each other and with neutral objects.

1.Unlike charges attract; like charges repel.
2.Coulomb’s Law – The electrostatic force is directly proportional to the product of the electrostatic
charges and inversely proportional to the square of the distance between them.
3.Electric charge distribution is uniform throughout an object or on its surface.
4.Electric charge of a conductor is concentrated along the sharpest curvature of the surface.

Associated with each electric charge is an electric field. The electric field points outward
from a positive charge into a negative charge.

Unlike Charges attract while like charges repel each other.

Using Coulomb’s Law, it can be determined that the electrostatic force is very strong when
objects are close but decreases rapidly as objects separate.

Electric charge distribution is uniform throughout an object.

When a diffuse nonconductor becomes electrified, such as a thundercloud, the electric charges are distributed rather uniformly throughout.

With electrified copper wire, excess electrons are distributed on the outer surface of the wire.

Electric charge of a conductor is concentrated along the sharpest curvature of the surface.

Electric charges have potential energy.  Electric charges gathered at one end of a wire create an

electric potential because the electrostatic repulsive force will cause some electrons to move along the wire

and work can be done.

The unit of electric potential is the volt (V).

Electric potential sometimes is referred to as emf (electromotive force) or more often as voltage.

In the U.S.A. the electric potential is 110 V.  Large appliances (x-ray units included) require 220 V. If voltage is

applied to a copper wire, then electrons move along the wire.  This is called an electric

current or simply, electricity.

The direction of electric current is important!  Electrons move from the area of highest

concentration to the lowest.  There is much confusion regarding electron flow versus current flow

because the early pioneers in electricity (i.e. Ben Franklin) assumed that the moving charges were positive versus negative.

The unfortunate result of the confusion is that:

The direction of electric current is always opposite to electron flow.

Electrical engineers speak of electric current, while physicists are concerned with electron flow.

Conductors:  any substance through which electrons flow easily. (examples include water and most

metals – copper is best)

Insulators:  any material that does not allow (or impedes) electron flow.

(examples include rubber, glass, clay and other earthlike materials)

Semiconductors:  a material that under some circumstances allows electrons to flow

and in other circumstances stops the flow. (examples include silicon and germanium)

At room temperature, all materials resist the flow of electricity.  Resistance decreases,

however, as the temperature of the material is reduced.

Superconductivity is the property of some materials to exhibit no

resistance below a very cold critical temperature.

Superconducting materials include niobium and titanium.

Video:  Magnetism:  Introduction to Magnetism  -  http://www.khanacademy.org/video/introduction-to-magnetism?topic=physics

Magnetism  -  a fundamental property of some material/matter

• humans are unable to sense a magnetic field but are able to sense

other characteristic properties of matter (i.e. mass, electrical energy,

etc.)

ANY CHARGED PARTICLE IN MOTION WILL CREATE A MAGNETIC FIELD.

• net magnetic field creates a magnetic domain which at the atomic level is referred

to as a magnetic dipole

• Under normal circumstances magnetic dipoles are randomly distributed in the body.
• when the body is brought into an external magnetic field the dipoles align

Spinning electric charges also induce a magnetic field.

• i.e. a proton in a hydrogen atom spins on its axis
• creates a nuclear magnetic dipole termed a magnetic moment
• basis for MRI

Magnetic dipoles in a bar magnet generate imaginary lines of a magnetic field.

When nonmagnetic material is brought into a magnetic field there is no disturbance in the field.

If ferromagnetic material, such as iron, is brought near the magnetic field the magnetic field lines will deviate.

Magnets are classified according to the origin of their magnetic property.

3 types  -                1.  Naturally Occuring Magnets  -  lodestones

-  ores  -  become magnetized by being in the Earth’s magnetic field for long

periods of time

2. Artificially Induced Permanent Magnets  -  i.e. bar magnets, compass

3. Electromagnets - electrically created magnets

Magnetism can be altered by heating, hitting with a blunt object.  Dipoles become jarred and randomly aligned  -  magnetic properties are lost.

Magnetic Material Classification

Nonmagnetic Materials  -  unaffected when brought into a magnetic field

- wood, glass, plastic

Ferromagnetic Materials  -  strongly attracted by a magnet

-  iron, nickle, cobalt

Paramagnetic Materials  -  slightly attracted by a magnetic field

- include platinum, aluminum

Diamagnetic Materials  -  weakly repelled by a magnetic field

-  beryllium, bismuth, lead and water

All magnets have a north and a south pole.

- comparable to a positive or negative electrostatic charge

Basic Law - like magnetic poles repel and unlike magnetic poles attract

The Earth behaves as though it has a “large bar magnet” embedded in it.

The Earth’s geographical North pole is its South magnetic pole.

S.I. Unit of Magnetic Force  =  TESLA

Common unit of Magnetic Force  =  GAUSS

1 Tesla  =  10,000 Gauss

Study Guide:  Final Examination

• Be able to define the following: matter, mass, energy, potential energy, kinetic energy, chemical energy, electrical energy, thermal energy
• Define ionization
• Identify the type of energy which encompasses x-radiation
• E = mc^2
• Energy transmitted through matter defines radiation
• Largest source of man-made radiation to general population is diagnostic x-ray exams
• Roentgen = unit of radiation intensity
• Be able to convert rads to gray and vice versa
• Be able to convert rems to Sieverts and vice versa
• For X-rays  -  1 rad = 1 rem = 1 roentgen
• Be able to calculate rads to rem using the quality factor for alpha particles (20)
• Know the rule for adding or subtracting fractions
• Know the rules for multiplying and dividing fractions
• Given a number, be able to identify the number of significant digits
• Know the rule for multiplying exponents
• Anything raised to the zero power = 1
• The three base quantities are: time, length and mass
• Secondary quantities are termed derived quantities
• Standard of length = meter
• Standard of mass = kilogram
• Standard of time = second
• Base quantities can be identified by the following systems: MKS, SI, CGS
• Differentiate between vector and scalar
• Velocity = speed
• Know the formula for calculating velocity
• Know the formula for acceleration
• Know all of Newton’s Laws
• Force = ma
• SI unit of force = newton
• Differentiate between mass and weight
• g on the earth = 9.8 m/sec^2
• g on the moon = 1.6m/sec^2
• know the formula for calculating momentum
• know the Law of Conservation of Momentum
• know the formula for calculating work
• know the unit for work
• define power
• know the unit for power
• 1  HP = 746 watts
• Differentiate between potential and kinetic energy
• Know the unit of heat
• Know the unit of velocity
• Know the means by which heat is transferred
• Be able to calculate Celsius to Fahrenheit and vice versa
• Know the boiling point of water in Celsius and Fahrenheit
• 92 is the total number of naturally occurring elements
• Know what Mendeleev’s contribution was to science
• Identify the smallest component of an element and a compound
• Know what group the Halogens are in
• Know what group the noble gasses are in
• Understand the relationship of electrons in an element to both periods and groups
• Know the three basic components of the atom
• Understand the Bohr model of the atom
• List the two types of bonds between atoms when molecules are formed
• Simple substances = elements
• Complex elements = compounds
• Define “nucleons”
• Differentiate between atomic mass number (A#) and atomic number (Z#)
• Define “isotope”
• Electron shells = different electron energy levels
• Innermost electron shell = k shell
• Atoms are electrically neutral
• To calculate the maximum number of electrons that can be in a given shell use the formula 2n^2
• Electron shell number = principle quantum number
• Outer shell of an atom can never have more than 8 electrons
• Center seeking force = centripetal force
• The closer an electron is to the nucleus, the greater is the binding energy
• Atomic number = number of protons in the nucleus
• Given the Z# and the A#, determine the number of neutrons in the atom
• Differentiate between isobar, isotone and isomer
• Beta emission = electron like particle emitted
• Alpha emission = alpha particle (2 p + 2 n)
• List the speed of light in m/s
• X-rays and gamma rays always travel at the speed of light
• Alpha particles have high LET
• X-rays do not come from the nucleus of a radioactive element
• Define frequency
• Define amplitude
• Wavelength = lambda
• Unit of frequency = hertz
• Wavelength and frequency are inversely proportional
• Increase wavelength, decrease penetrating ability of beam
• Be able to use the inverse square law
• Know the range for orthovoltage
• Plank said that x-rays either exist at the speed of light or they don’t exist at all
• Pair production = conversion of energy into mass
• Differentiate between electrostatics and electrodynamics
• Earth = electric ground
• Like charges repel, unlike charges attract
• Be familiar with Coulombs Law as it relates to electrostatic force
• Electric charges are concentrated along the sharpest curvature of an object
• Electric potential = electromotive force = voltage
• Conductors allow electrons to flow easily
• Rubber = insulator
• Know Ohm’s law and how to use it
• Know all of the rules for series and parallel circuits and how to use them
• AC – electrons oscillate back and forth
• DC – current flows in one direction only
• In the U.S.A., AC is defined as a 60 hertz current
• Electric power measured in watts
• P=IV
• Moving charges induce magnetic fields perpendicular to their motion
• Electromagnet = current carrying wire around an iron core
• Magnetic south pole of the earth = north geographic pole/the Arctic
• SI unit of magnetic strength = tesla
• Ferromagnetic materials = iron, nickel, cobalt
• Know materials which are diamagnetic, ferromagnetic and non-magnetic

Mass is measured in kilograms.

Weight is measured using a unit called the Newton.

Weight is determined by the gravitational force exerted on a body.

As an example, a student having a mass of 75 kilograms would weight 735 Newtons on the Earth but weight only 120 Newtons on the moon.

ass is measured in kilograms.Weight is measured using a unit called the Newton.Weight is determined by the gravitational force exerted on a body.As an example, a student having a mass of 75 kilograms would weight 735 Newtons on the Earth but weight only 120 Newtons on the moon.  Mass is measured in kilograms.Weight is measured using a unit called the Newton.Weight is determined by the gravitational force exerted on a body.As an example, a student having a mass of 75 kilograms would weight 735 Newtons on the Earth but weight only 120 Newtons on the moon.  Mass is measured in kilograms.

Weight is measured using a unit called the Newton.

Weight is determined by the gravitational force exerted on a body.

As an example, a student having a mass of 75 kilograms would weight 735 Newtons on the Earth but weight only 120 Newtons on the moon.