1 The Force and Nature of Magnetism - High Point University · The Force and Nature of Magnetism ... Some postulate that when lightning strikes a ... lodestone on a piece of wood

The Force and Nature of Magnetism

What Impact Does Magnetism Have In Our World?

ELECTRONIC EVIDENCE #2

Most people understand a magnet to be the

item you put on your refrigerator. What

the majority of the public does not know is

that without magnets, society would not

function like it does today.

Without the force of magnetism, or the knowledge of it, we

would not be able to navigate without the sun or stars. In

addition, we would not be able to run most electronics, from a

loudspeaker to a car or a plane. The medical field would not

be advanced enough to diagnose diseases within hours, or to

even detect cancerous tumors. Without magnetism, stores and

libraries would not be able to have anti-theft security systems.

Similarly, security forces such as those in airports would not

be able to scan people for weapons with metal detectors.

Migrating animals use magnetism to find their proper habitats

and without it entire species could die. In fact, without the

Earth’s magnetic field, the entire planet would erode away.

Magnetism is clearly an unseen force that our world depends

on immensely.

www.ak05.co.nz

Magnetic Resonance Image

www.hearthealthywomen.org

1

The movement of charged particles causes

magnetism. To understand the magnetic

properties of a substance, one would need to

look at the motion of electrons within the

material. (Wysession, 2005)


THE DISCOVERY OF MAGNETISM

Ancient societies of China, Rome, and Greece first

discovered magnetic forces. They observed that a

rock called the lodestone would attract other

lodestones. It has been discovered since that this

occurs because the lodestone contains iron ore, or

magnetite, which is a magnetic substance. Even

today, scientists have still not discovered what

makes lodestones magnetic, partly because it can be

found all around the world, not just in one particular

area. Some postulate that when lightning strikes a

rock rich in iron, a lodestone is formed.

(Coffey, 2011)

(Magnets & Magnetism, 2006)

Lodestone

www.clipart.dk.co.uk

The lodestone was used by many seafaring nations to

aid sailors in navigation. They would place a small

lodestone on a piece of wood and float the wood in

water. The sailors knew this would always point the

same direction, which we know today to be North.

This contraption was very handy when navigating

when the sun or stars were not visible, as that was the

usual method of navigation. The first known writings

on the utility of the lodestone as a compass can be

dated to 1269, when a Frenchman named Petrus

Peregrinus published some scientific writings.


(Gunderson, 2005)

The lodestone is a special type of the

mineral magnetite. All magnetite rocks

possess magnetism, but the lodestone

has a specific north south polarity.

Once early civilizations discovered

this, they began making the first

compasses.

(Brand, 2012)

Lodestone

www.magnet.fsu.edu

The first known reference to the

lodestone and its abilities was by a

Greek philosopher, Thales of

Miletus, in 600 BC. Thales noted

its properties, but could only think

to attribute them to animism, a

phenomenon that suggests the

lodestone had a soul.

(Brand, 2012)

2


THE FIRST COMPASSES

1000 BC- Olmec’s located near San

Lorenzo, Veracruz, Mexico seemed to use

a bar of magnetized iron, which was a

part of a larger instrument, in orienting

their cities and buildings in a north-south

direction. Though this bar now points

approximately 35 degrees from magnetic

north, experts say it could have been

more reliable in the time it was used.

(Olmecs, 1975)

200 AD- Chinese civilizations sculpted

magnetite into spoon shaped compasses.

They called these early compasses south

pointers. Though they did not have all the

information we do at present, this name

acknowledges that compasses actually

point to the magnetic north pole, which is

in fact towards the geographic south of

the Earth. (Wysession, 2005)

1150- Chinese navigators began using

compasses with magnetic iron needles.

(Wysession, 2005)

1400’s- News of the Chinese magnetic

compass traveled to Europe and made

Columbus’s voyage to America in 1492

possible. (Pumfrey, 2000)

Viking Compass

www.archaeology.org

Chinese Compass

www.magnet.fsu.edu

Floating Compass

www.tcd.ie/

3

1500’s- A crystal called an Iceland spar was used

even on cloudy days to gather the sun’s position

within a few degrees of accuracy. This

transparent calcite crystal explains how Vikings

navigated. When light is passed through the

crystal, it is split in two, and by manipulating

these beams, Vikings looked for the point where

the beams were equally bright and lined up. This

place could show them the location of the sun.

(Swaminathan, 2012)

1700’s- Sir Augustus Charles Gregory, an

Australian Surveyor-General designed the

Gregory Pattern Compass that granted explorers

the ability to point to true north even through the

rough terrain. (Long Lost Compass, 2010)


Declination Declination

All of these explorers discovered or

observed magnetic declination. Declination

is the phenomenon that proves the magnetic

poles are not in the same position as the

geographic poles. The geographic poles are

aligned with the Earth’s axis, whereas the

magnetic poles’ locations can vary.

Currently, the magnetic North Pole is in

northern Canada positioned at 81 degrees

north latitude, whereas the geographic

North Pole is located at 90 degrees north

latitude. Many scientists believe this

variation is caused by the nature of the

magnetic field of the Earth, also known as

the magnetosphere. When electric currents

pass through the Earth’s core, which is

made of molten iron, the magnetosphere is

created and altered. Because the currents

and the iron in the Earth’s core are flexible,

the magnetic poles move also. Since the

discovery of the magnetic north pole in

1831, it has moved about 800 kilometers. It

continues to drift at about 35 miles per year.

When a compass needle is shown to defer

from another indicator of north, magnetic

declination is showing. This happens

especially when one is close to the any of

the poles.

(Coffey, 2011)

(Gunderson, 2005)

(Wysession, 2005)

1492- As Columbus was crossing the Atlantic, he

noticed the compass needle direction deviated slightly

from the north that the stars pointed to. As he

progressively got closer to the Americas, he noticed

the difference kept increasing. (Gunderson, 2005)

1400’s- Portuguese explorers who traveled long

distances in the Atlantic Ocean noticed that the small

errors that were insignificant for trips in the

Mediterranean Sea became more significant and

caused navigational errors. Then, they began

observing and recording the differences between the

compass and the sun to map these discrepancies.

(Leitao, 2011)

1500’s- Some of the observations of variations by

Portuguese sailors were attributed to failure of the

lodestone used to magnetize the compass needle or

the needle itself. (Keller, 2000)

1804- As Meriweather Lewis and William Clark

traversed the Louisiana Territory at U.S. President

Thomas Jefferson’s request, they recorded both

compass position and the placement of the sun or

North Star, as they knew relying on the compass

alone would be negligent because of its known

unreliability. (Ramsayer, 2003)

1818– Reverend George Fisher noticed that

magnetism disrupted the reading of a chronometer,

which determined time, and therefore longitude, when

at sea. (Roberts, 2009)

Declination

www.magnetic-declination.com

Map of Declination

www.thecompassstore.com

4


Though we refer to the pole that the north

compass needle points to as the magnetic North

Pole, since the poles of a magnet, such as a

compass needle, are attracted to their opposite,

the compass is actually pointing to the magnetic

south pole. However, it is still normally called

magnetic north because geographically it is

located in the northern hemisphere. In addition,

the poles can switch when the magnetosphere

reverses. In fact, in the last 3.5 million years, the

poles have switched nine times.

(Wysession, 2005)

(Gunderson, 2005)

The Solution to

Magnetic Declination

The Dip Compass

Many navigators had noticed that occasionally

compasses would point downward instead of just

horizontal direction. In 1581, Robert Norman, an

untrained compass maker, observed this

phenomenon while flying over the poles. Norman

then tried to make the compass vertical to see how

the needle would react. This apparatus was a dip

needle. A dip needle is similar to a compass in the

make, but is used primarily close to the poles.

Because compasses become unreliable near the

poles, navigators now use dip needles to show the

inclination of the Earth’s magnetic field, and

therefore the location of north when they near the

poles.

(Gunderson, 2005)

(Pumfrey, 2000)

The Earth’s Magnetic Field

www.physics.sjsu.edu/

Early Dip Compass

www.etc.usf.edu

Modern Dip Needle

www.pasco.com

5


Horseshoe Magnet

www.magnetmaterialyl.com

Bar Magnets

www.cpsc.gov

Magnets like these are made of

different cells, called domains. All of

the molecular magnets in one domain

point in one direction, which makes it

a small magnet. However, because all

the neighboring domains point in

different directions the entire material

is not a magnet. When all the

domains are pointing in different

directions, their magnetization

cancels out. Once magnetized, all the

domains line up to point in the same

direction. Then the magnetic forces

of each domain reinforce each other.

This is known as the domain theory

of magnetism.


(Gunderson, 2005) Domain Diagram

www.magnet.fsu.edu

Magnetic Force

www.education.vic.gov.au

A magnet can exert force

on other magnets or magnetic

objects. This force can cause

another object to move or

change. The force of a magnet is

strongest nearest its poles.

Magnetic force can even act

over a distance, though the force

will diminish with distance.

(Wysession, 2005)

(Kirkland, 2007)

Magnetic Force

MAGNETIC MATERIALS

All magnets have 2 poles, a

north pole and a south pole.

Even if a magnet is cut in half,

it will still form two poles.

Similar poles repel each other.

Therefore, a north pole will

never be attracted to another

north pole. Unlike poles

attract, so one will always see

north and south poles pulled

together.


(Gunderson, 2005)

(Kirkland, 2007)

Magnetic Poles

Pole Attraction

www.howmagnetswork.com

Not every metal is attracted to a magnet.

Only iron, steel, nickel, cobalt, and other

magnets can be affected by a magnet’s

magnetic force.


6


Magnetic Fields

Magnetic Field of a Bar Magnet

www.ece.neu.edu

Around every magnet there is an invisible field where the

force of the magnet can be detected. This space is the

magnetic field of a magnet. The field is usually stronger

near the poles and the further you get away from the

magnet, the weaker the field gets. Lines can display the

magnetic field of a magnet. These field lines begin at the

north pole and extend around the magnet to the south

pole. The closer the lines are together, the stronger the

magnetic force at that point. To find the magnetic field of

a magnet you place a piece of paper over the magnet and

sprinkle iron filings over it and the field lines will form

out of the filings.


(Wysession, 2005)

CREATION OF A MAGNET

While there are naturally magnetic

rocks found on Earth, most magnets

used today are manmade. There are two

different ways to create a magnet.


Single Touch Method

www.need.org

Stroke one pole of a bar magnet

in the same direction on a

magnetic object, such as a

needle, 10 to 15 times.


This creates an

electromagnet, which

utilizes electricity to

create a magnetic field.

(Wysession, 2005)

ELECTRIC METHOD

Single Touch Method

M ICRO S O FT

Place a steel or

iron bar, such as a

nail, inside a

solenoid, or coil of

wire, then attach

both ends of the

wire to either end

of a battery. Pass

current through

the solenoid using

the battery and a

magnetic field

forms around the

nail.

(Wysession, 2005)

www.mgitecetech.wordpress.com

7


Electromagnets HPU

Hard & Soft Magnetic Materials

MICROS OFT

8

Iron and similar materials are easily magnetized. This

means the domains in the material line up in the same

direction easily. However, once the magnetic influence

is removed, the substance loses its magnetism because

the domains revert to pointing in different directions.

These are soft materials that serve as excellent

temporary magnets. These soft materials are used in

electromagnets, so the material loses its magnetism

once the current is turned off. Steel on the other hand is

a hard, or ferromagnetic, material. This means it is

difficult to line up the domains in the same direction,

and therefore difficult to magnetize. However, once the

domains do line up, they remain in that position after

the magnetic influence is removed, creating a

permanent magnet. However, even with a magnet made

out of a hard material, if it is jolted or dropped, it can

lose its magnetism eventually.


Diamagnetic– materials

align in opposition to an

applied magnetic field.

Ferromagnetic– materials

become magnetic in the

presence of another

magnetic field and remain

magnetic after the external

field is removed.

Paramagnetic– materials

become strongly magnetic

in the presence of an

external magnetic field,

but return to their original

state when the force is

removed. This

phenomenon is induced

magnetism.

(Magnets & Magnetism,

2006)

(Wysession, 2005)

In an electromagnet, the uniform motion

of electrons throughout the solenoid

creates the magnetic field. Therefore,

when the power source, normally a

battery, is connected, the current is

flowing through the solenoid and the

ferromagnetic material inside it

emanates a magnetic field. However,

when the power source is not releasing

current, there is no magnetic field.

(Wysession, 2005)

The strength of an electromagnet depends on

the amount of current, number of loops in the

solenoid, and its type of ferromagnetic core.

(Wysession, 2005)

Electromagnetism was first found in 1820 when

Danish scientist Hans Christian Oersted

observed that as electric current passed through

a wire, a nearby compass needle twitched. After

years of study, in 1845 Michael Faraday

developed the theory of electromagnetism as

we use it today.

(Highfield, 2010)

Powerful Electromagnet

www.howstuffworks.com

www.how-things-work

-science-projects.com


REAL WORLD APPLICATIONS

Magnetism is powerful enough to levitate a

train. Magnetically levitated trains, or

MAGLEV trains, use electromagnets to lift

the train cars off the ground. Then, these

trains travel along thin magnetic tracks,

which can propel the trains up to 300 miles

per hour. This speed is not possible with

normal train tracks as friction slows the

train significantly. So far, only Japan and

Germany have perfected and implemented

MAGLEV trains.

(McCartney, 2008)

(Gunderson, 2005)

Transportation

MAGLEV Train

www.railsystem.net

Electromagnets

Many common items use electromagnets, such as

electric motors, loudspeakers, electric bells, relay

switches, microphones, televisions, metal detectors,

traffic light sensors, and computers.

(Wysession, 2005)

(Gunderson, 2005)

Information can be

stored on a small

magnetic strip on a

card. These cards

can be used for

credit cards, debit

cards, laundry

machines, parking

meters, and copiers.

Tape recorders and

computer disks also

store information in

magnetic fields.

(Kirkland, 2007)

Information

Storage

BIOMAGNETS

Companies that create

biomagnets claim they increase

healing and decrease pain by

affecting charged particles in the

bloodstream to flow faster and

therefore increase circulation.

Biomagnets are not approved by

the FDA however, so their usage

has not become widespread yet.

(Gunderson, 2005)

Gas Gauge www.wemausa.com

Galvanometers

A galvanometer uses an

electromagnet to move

a pointer on a dial. The

pointer measures the

amount of current in the

solenoid. This type of

device is used in cars to

measure the amount of

gas remaining in the

tank. A sensor in the

tank reduces the current

as the level decreases

and the pointer reacts.

(Wysession, 2005) Traffic Light www.drcarolshow.com

Credit Card Magnetic Strip www.teach-ict.com

9


REAL WORLD APPLICATIONS

MRI MACHINES

Magnetic resonance imaging machines were

invented by Sir Peter Mansfield in the 1970’s as a

way to obtain two-dimensional images of the

human body. An MRI machine uses a very

powerful manmade magnetic field 40,000 times

stronger than the Earth's to look at the tissues and

organs in the human body. An MRI machine uses

four different magnets. The first magnet is very

powerful and is used to immerse the patient in a

large steady magnetic field. The other three

magnets create variable fields each in a different

dimension. One set goes head to toe along the

length of the body. The next magnet goes from the

top of the body through it to the bottom. The final

magnet goes left to right through the body width

wise. This method is much more effective then x-

rays, which are more appropriate for examining

bones. In addition, x-rays are more dangerous

because prolonged exposure to that type of

radiation can be harmful to the body. Therefore,

the advent of magnetic resonance imaging changed

the medical field immensely as now infections can

be safely diagnosed in hours instead of days.

(Rezende, 2006) (Wysession, 2005)

(Kirkland, 2007) (Hamzelou, 2011)

www.medwow.com

Anti-Theft Devices

In the 1960’s a security device was invented using

electromagnetic waves to identify objects that have

been tagged with magnetic material. An activated

tag is demagnetized, so when it passes through the

electromagnetic current passing in between the

pedestals normally located in front of the exit doors,

the waves being to magnetize the tag. A receiver in

the pedestals detects the change in the domains of

the tag and sets off the alarm sound. A deactivated

tag has been magnetized after being checked out by

powerful magnets often housed in a rubber pad.

Then, since the tag is already magnetized, its

domains do not change as it goes through the

electromagnetic waves, and therefore does not set

off the alarm.

(Wysession, 2005)

Anti-Theft Pedestals

www.ambaelectronics.com

Metal detectors also use magnetic fields

produced by electric current to detect any

ferromagnetic material such as iron and steel that

is in most weapons like guns and knifes. If the

sensitivity of a metal detector is high, it will also

set off the alarm when it senses other metal

objects, such as coins. (Metal Detector, 2005)

10


CONNECTIONS OF MAGNETISM

MATH AND SCIENCE

Magnetoreception

Loggerhead Sea Turtle

www.mydailyclarity.com

The Earth's magnetic field serves many

purposes, one of which is protection. The

magnetic field guards the earth from solar

wind that could eventually eradicate the

planet. In fact, Jupiter has begun to erode

due to solar wind, though its strong magnetic

field has allowed it to recapture escaping

gases and therefore maintain its mass.

(Semenivk, 2009) (Gaensler, 2009) Earth’s Magnetic Field Deflecting Solar Wind

www.astronomygcse.co.uk

Magnetic storms are disruptions in the Earth’s

magnetic field. These changes can be sensed on

the ground using magnetometers. Magnetometers

measure the magnitude of magnetic storms in units

of Teslas with comparison to time. These records

can then be plotted to show the progression of a

storm. The Pythagorean Theorem can also be used

to calculate the magnitude of a magnetic field.

However, because magnetism exists in three

dimensions, this requires the three dimensional

Pythagorean Theorem, which is

where x, y, and z are the coordinates of a point in

space. This formula can be used to calculate which

cities have the highest magnetic field strengths.

(Odenwald, 2006)

222 zyxD

Magnetic Storm Graph

www.image.gsfc.nasa.gov

Intense research and numerous studies

have shown that many animals

including robins, bacterium, warblers,

lobsters, salmon, zebrafish, trout,

sharks, rays, loggerhead turtles, naked

mole rats, bats, pigeons, cattle, monarch

butterflies, honeybees, ants, elephant

seals, and whales all have a special

sense called magnetoreception. This

sense allows them to have the ability of

a compass, that is, to know

directionality and navigate through

unknown areas. Some of these animals

have even shown the ability to not only

sense direction, but also distance from

the poles.

(Yong, 2010) (Castelvecchi, 2012)

11


Brand, M., Neaves, S., & Smith, E. (2012). Lodestone. National High Magnetic Field Laboratory.

Retrieved from http://www.magnet.fsu.edu/education/tutorials/museum/lodestone.html.

Castelvecchi, D. (2012). The compass within. Scientific American, 306(1), 48.

Coffey, R. (2011). 20 things you didn’t know about magnetism. Discover, 32(6), 96.

Did Olmecs have first compass? (1975). Science News, 108(10), 148.

Gaensler, B. (2009). The magnetic universe. Australian Science, 30(1), 22-25.

Gunderson, P.E. (2005). Magnetism, electromagnetism, and electronics. Handy Physics Answer Book. Canton, MI:

Visible Ink Press.

Hamzelou, J. (2011). Magnets cut diagnosis time for infections by days. New Scientist, 210(2810), 9.

Highfield, R. (2010). Electromagnetism. New Scientist, 207(2777), 34.

Keller, A. (2000). Navigation. Encyclopedia of the Scientific Revolution, 453.

Kirkland, K. (2007). Electricity and Magnetism. New York, NY: Facts on File.

Leitao, H. & Alvaraz, W. (2011). The Portuguese and Spanish voyages of discovery and the early history of geology.

Geological Society of America Bulletin, 123(7), 1226-1228.

Magnets & magnetism. (2006). Research Machines, 1.

McCartney, R., Deroche, S., & Pontiff, D. (2008). Can trains really float? Science & Children, 45(7), 33.

Metal detector. (2005). Aviation Week & Space Technology, 163(8), 84.

Odenwald, S. (2006). Extra credit problems in space science. Exploring Space Science Mathematics, 14 & 17. Retrieved

from http://image.gsfc.nasa.gov/poetry.

Proof of long-lost compass. (2010). Australian Geographic, (99), 19.

Pumfrey, S. (2000). Compass, magnetic. Encyclopedia of the Scientific Revolution, 156.

Ramsayer, K. (2003). North vs. northwest. Science News, 164(14), 213.

Rezende, L. (2006). Chronology of Science. New York, NY: Facts on File.

Roberts, G.W. (2009). Magnetism and chronometers: The research of Reverend George Fisher. British Journal for the

History of Science, 42(1), 57-72.

Semenivk, I. (2009). Can magnetism save a vaporizing planet? Sky & Telescope, 118(6), 16.

Swaminathan, N. (2012). The Vikings’ Crystal Compass? Archaeology, 65(2), 20.

Wysession, M., Frank, D., & Yancopoulos, S. (2005). Physical Science Concepts in Action: Teacher’s Edition for North

Carolina. Upper Saddle River, NJ: Pearson Education.

Yong, E. (2010). Masters of magnetism. New Scientist, 208(2788), 2.

References

Pictures www.ak05.co.nz

www.ambaelectronics.com

www.archaeology.org

www.astronomygcse.co.uk

www.clipart.dk.co.uk

www.cpsc.gov

www.drcarolshow.com

www.ece.neu.edu

www.education.vic.gov.au

www.etc.usf.edu

www.hearthealthywomen.org

www.howmagnetswork.com/ www.howstuffworks.com

www.how-things-work-science-projects.com

www.image.gsfc.nasa.gov

Pictures

12

www.magnet.fsu.edu

www.magnetic-declination.com

www.magnetmaterialyl.com

www.medwow.com www.mgitecetech.wordpress.com

www.mydailyclarity.com

www.need.org

www.pasco.com

www.physics.sjsu.edu/

www.railsystem.net

www.tcd.ie/

www.teach-ict.com www.thecompassstore.com

www.wemausa.com

Documents

1 The Force and Nature of Magnetism - High Point University · The Force and Nature of Magnetism ... Some postulate that when lightning strikes a ... lodestone on a piece of wood