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Transcript of (SPH4U0) EMG

A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials
The Law of Magnetic Poles:
Opposite Poles Attract
Similar Poles Repel
Moving Electric Charges produce a magnetic field

Domain Theory of Magnetism:
* There are tiny magnetic homogenous regions called dipoles in ferromagnetic substances; each domain acts like a bar magnet.
Right Hand Rule for a Straight Conductor
If the conductor is grasped in the right hand, with the thumb pointing in the direction of the current, the curled fingers point in the direction of the magnetic field line

If the coil is grasped in the right hand, with the fingers curled in the direction of the electric current, the thumb points to the direction of the magnetic field lines in its core.
Display Technologies which are designed to mimic the appearance of ordinary ink on paper
Contains clear micro capsules the diameter of a human hair each filled with dozens of tiny white beads suspended in a dark liquid.
The white beads are negatively charged. They are sandwiched between base and clear insulators.
Giving the base a positive charge causes the white negative beads to sink to the bottom, making it look like the pixel is black.
Similarly a negative charge on the base causes the white beads up giving it a white look. It allows one to form characters and drawings on the computer.

An Electrostatic Precipitator is a particulate collection device that removes particles from a flowing gas (such as air) using the force of an induced electrostatic charge
Are air pollution control devices that remove tiny particles from the emissions of processing and power plants that burn fossil fuels
Directly adds the properties of electric fields. A large negative charge is place on wires, and the electric field near the wire is very strong, so the particles become ionized
The electrons are put through a positive plate, where they attach themselves to collector plates

• Opposite Attract
• Similar electric charges repel
• Charged objects attract some neutral

A field is a region in space surrounding a given object where that object exerts force on another object
Forces that “act at a distance” have fields associated with them

Electric Field Lines
Start on positive charges; end on negative charges
Follow the direction taken by a positive test charge
Never cross
The density of field lines show the strength of the electric field

Coulombs law gives us the electrical force of attraction or repulsion between two charges q 1 and q 2 separated by a distance r:
If q1 and q2 are both positive / oppositely charges, then the force is repulsive / attractive and positive work is done to bring the 2 charges together / further apart

The force between two point charges is inversely proportional to the square of the distance between the charges and directly proportionate to the product of the charges.

Millikan’s Experiment – Produced a small droplet with an atomizer, allowed to fall freely and then under the influence of a constant electric field
Through this he determined the elementary charge
E= 1.602 x 10 ^ -19 C

(Law of Conservation of Charge- The total charge (the difference in amount between positive and negative charges) within an isolated system is always conserved)
Whenever an electric current flows in a conductor, a magnetic field is created around the region of the conductor

Electric Potential Energy and Electric Potential
Electric Potential energy is the enrgy stored in a system of two charges held a distance apart.
The electric potential energy stored in a system of two charges ; q1 and q2 is defined by the equation:

A current carrying conductor in the presence of an external magnetic field will experience a force that is perpendicular to both the current and the magnetic field directions.

Fm = I L B Sin θ
Fm = Magnetic force in Newton’s
I = Current in Amperes (coulombs / second)
L = Length of conductor in magnetic field
B = External magnetic field (Tesla)
Θ= Angle between current direction
• The maximum force occurs when I and B are at an angle of 90 degrees.

The magnitude of the force on the conductor f is in a direction perpendicular to both the magnitude of the magnetic field B and the direction of the current I: in SI units
Gravitational field is a model used to explain the influence that a massive body extends into the space around itself, producing a force on another massive body.
It exists in a space around an object where the force of gravity is felt

Friction = Substances acquire an electrical charge when they are rubbed with other substances
Contact = When a charged object meets a neutral object, the objects share the excess of electrons.
Induction = The charging of an isolated conducting object by momentarily grounding it while a charged body is nearby.

* Both are inverse square laws
* The force works by joining the centers of the masses or charges
* The magnitude of the force is the same as the force that would be measured if tall the mass or charge is concentrated at a point at the center of the spheres.
* Electric Force can repel and attract/ Gravitational force can only attract
* The Universal Gravity constant is very small compared to the constant for Coulomb's law.
G = 6.67 x 10 ^ -11 N*m^2 / kg^2
k= 9.0 x 10 ^ 9 N*m^2/c^2

Field Theory
The theory that explains interactions between bodies or particles in terms of fields.

Fg = the magnitude of the force of gravity
G = the universal gravitation constant
m = the mass of the body influenced by the gravitational field
M = the central bodies mass
R = the distance between the centres of the 2 bodies

A satellite that needs to maintain a stable
circular orbit around the earth must maintain a specific velocity that depends on the mass of the earth and the radius of the satellites orbit

To analyze the motion of a satellite in UCM, Newton's Law of Universal Gravitation is combined with Centripetal acceleration involving the satellites speed.
Earth and Its Magnetic Fields
Electric Fields
The Science Behind It
The Three Right Hand Rules:

The magnitude of the magnetic force on a charged particle
Is directly proportional to the magnitude of the magnetic field (B) ,the velocity (v) and the charge of the particle (q)
Depends on the angle between B and V
If its a right angle then the particle is perpendicular to the field lines
If it is 0 or 180, then the particle is parallel to the field lines

Fm = q v B Sin θ

F m = the magnetic force (N)
q = charge of the particle (C)
v = velocity of the particle (m/s)
B = the magnetic field strength (T – this is the Tesla 1 T=1 kg/C µ s)
Θ = the angle between B and V

Electric charges on objects results from an access or a deficit of electrons. Thus the charge of an object simply requires a transfer of electrons to and from the object.
Removing electrons results in an object that is positively charged
If electrons are added then the object would be negatively charged
Since electric charges are created by an excess or a deficit of electrons, we can use the fundamental charge to calculate the number of excess or deficit electrons that are on an electric charge.


q= the charge that is given by the object (Coulombs)
N= the number of electrons on the object
e= 1.6 x 10 ^ -19 Coulombs

Calculate the charge on a small sphere with an excess of 5.0 x 10 ^14.

Solution :
N= 5.0 x 10 ^14
e = 1.6 x 10 ^ -19 C
q= Ne
= (5.0 x 10 ^14) x (1.6 x 10 ^ -19 C)
q= 8.0 x 10 ^-5 C
The charge on the sphere is - 8.0 x 10 ^-5 C, since there is an excess of electrons.

Charles Augustin de Coulomb experimentally established the nature of electric force between charged particles

k= 9.0 x 10 ^9 Nm^2/c^2
fE= magnitude of the electric force
q= magnitude of the charges on the 2 objects
r= distance between the two objects
What is the magnitude of the force of repulsion between two small spheres 1.0 m apart, if each has a charge of 1.0 x 10 ^-12 C

q1 = q2 = 1.0 x 10 ^ -12 C
r=1.0 m
k= 9.0 x 10 ^9 Nm^2/c^2

fE= (kq1q2)/ r^2
= ((9.0 x 10 ^9 Nm^2/c^2) (1.0 x 10 ^ -12 C) ^2 )/ (1.0)^2
= 9.0 x 10 ^ -15 C
The magnitude of the force is 9.0 x 10 ^-15 C.

Drawing field lines
Any charged object will create an electric force field around it; any other charged object near the object feel a force of attraction or repulsion.
The electric field at any point is defined as the electric force per unit positive charge and is a vector quantity.

E = Fe / q
E= Electric field at any given point (vector quantity)
Fe= Electric Force
q= Test charge

E = kq1 / r^2
E= Electric field at any given point (vector quantity)
k= Coulomb's constant
9.0x 10 ^9 N*m^2/ C^2
q1 = charge on the sphere
r = Any distance from the object

The potential difference between two points in an electric field is given by the change in the electric potential energy of a positive charge as it moves from one point to another.
Electric Potential is a property of the electric field of the charge q1. It represents the amount of work necessary to move a positive unit test charge from rest to any specific point in the field of q1.
Electric Potential energy can be either positive or negative, depending on the signs of the charges
Work is done for the attraction or repulsion of two charges
Electric Potential Energy due to charge Q: Voltage
This is the potential energy per unit positive charge at any point in space due to Q.
Units: Joules/ Coulomb or Volts (1 V = 1 J/C)
A charged particle in a uniform electric field moves with uniform acceleration. A charge will accelerate in the direction of the electric force according to Newton’s second law.
The total kinetic energy in a particle stays the same even when the distance changed.
When moving in an electric field the charged particles kinetic energy result can change if the objects electric potential energy changes.
The charged particle q1 moves in the electric field of q2 in such a way that the electric potential that is loses is equal to the kinetic energy that it gains.

The Motion of Charged Particles in an Electric Field.
Gravitational Fields

The force that attracts an object to a physical body that has mass

The Earth's Gravitational Field
Law of Universal Gravitation
Newton was led to believe that gravity depends on distance and thus he created the Law of Universal Gravitation.
Newton believed that the force of gravitational attraction between any two objects is directly proportional to the product of the masses of the objects, and inversely proportional to the square of the distance between the centers.
This law of universal gravitation applies to all bodies in the solar system, from the sun to planets, moons and artificial satellites.

The gravity of Earth, denoted g, refers to the acceleration that the Earth imparts to objects on or near its surface
In SI units this acceleration is measured in meters per second squared (m•s2) or Newton’s per Kilogram N/kg2
The strength of Earth's gravity varies depending on location.
The nominal "average" value at the Earth's surface is 9.80665 m/s2 or about 32.1740 ft/s2).

The Law of Universal Gravitation
Sample Question
Determine the magnitude of the force of attraction between two uniform metal balls, of mass 4.00 kg, used in women’s shot putting, when the centers are separated by 45.0 cm.

G= 6.67 x 10 ^-11 NM^2/kg^2
R= 0.450 m
Fg= ?
m1= m2= 4.00 kg

Fg= (Gm1m2)/ r^2
Fg = [(6.67x 10 ^-11 Nm^2 / kg^2) (4.00 kg)(4.00kg)] / (0.450 m)^2
Fg= 5.27 x 10 ^-9 N

The magnitude of the force of attraction is 5.27 x 10 ^-9 N, an extremely small amount.

0:25 - 1.08
Sir Isaac Newton's Discovery
The strength of the gravitational field is directly proportional to the square of the distance from the center of that body and that the gravitational field exists in a space surrounding an object in which the force of gravity is exerted on objects.

g= GM/ r^2

g= magnitude of the gravitational field strength
G= Universal Gravitation constant (6.67x 10 ^-11 Nm^2/kg^2
M= The mass of the object
r= radius

Sample Question
Determine the mass of earth using the magnitude of the gravitational field strength at the surface of the Earth, the distance r between Earth's surface and its center (6.38 x 10 ^ 6 m), and the universal gravitation constant.

g= 9.80 N/kg
r=6.38 x 10 ^6 m
G= 6.67 x 10 ^ -11 Nm^2 / kg ^2
M= ?

g= GM/ r^2
M= gr^2/ G
M= [(9.80 N/kg) (6.38 x 10 ^6 m)^2]/ (6.67 x 10 ^-11 Nm^2 / kg^2)
M= 5.98 x 10 ^24 kg

The mass of Earth is 5.98 x 10 ^ 24 kg.

• The Gravitational Potential Energy of a system of 2 spherical masses is directly proportional to the product of their masses, and inversely proportional to the distance between their centers
• The gravitational potential energy of zero is assigned to an isolated system of two masses that are so far apart, that the gravity between them has dropped to zero

Gravitational Potential Energy

• Escape speed is the minimum speed needed to project a mass m from the surface of mass M to just escape the gravitational force of M
• Escape kinetic energy is the minimum kinetic energy needed to project a mass to escape the gravitational force of M.
• Binding energy is the amount of additional kinetic energy needed by a mass m to escape from a mass m

Escape Energy and Escape Speed
Did you know?
The universal gravitation constant, G= 6.67 x 10 ^ -11 N*m^2/ kg^2, was first determined experimentally by Henry Cavendish in 1798.
Satellites can be natural, such as moons and planets, or artificial, such as the Hubble Space Telescope.
A satellite is pulled by earth's Gravity towards earth follows a curved path. Since earth's is curved, the satellite falls downward at the same rate as Earth's curvature.
This equation indicates that for a satellite to maintain an orbit of radius r, its speed must be constant.

G= 6.67 x 10 ^-11 Nm^2 / kg^2
r= 6.98 x 10 ^ 6 m
me= 5.98 x 10 ^24 kg
v = ?

v = Square root (G*me/r)
v= square root [ ((6.67x 10^-11)(5.98x 10^24))/(6.98x 10 ^6)]
v= 7.56 x 10^3 m/s

The required speed is 7.56 x 10 ^ 3 m/s.

Magnetic Fields
Magnetic Poles
Domain Theory

A magnet is an object or a material that produces a magnetic field.
Poles are the regions at the end of a magnetized body at which the magnetic attraction is the strongest
Right Hand Rule for a Solenoid
Right Hand rule for Magnetic Force
Measuring Magnetic Force
If the thumb points in the direction of the current (flow of positive charge), and the extended fingers point in the direction of the magnetic field, the force is in the direction in which the right palm pushes.
The Magnetic Force on a Conductor

• Travel from north to south outside of a magnet
• Travels from south to north inside of a magnet
• Magnetic fields never cross, they create loops
• The magnetic field’s strength is shown by the lines. The smaller the distance, the bigger the attraction/ repulsion

Properties of Magnetic fields
The Principle of Electromagnetism
A magnetic field is produced by moving electrons. These moving electrons cause a magnetic dipole
Magnetism only occurs when the dipoles point in the direction of the magnetizing field. The magnetic material is then fully magnetized. If the dipoles point in random directions then the material is not magnetized.

What causes Magnetism?
The Science Behind it

An electron accelerates from rest in a horizontally directed electric field through a potential difference of 46 volts. The electron then leaves the electric field, entering a magnetic field of magnitude 0.20 T directed into the page. The initial speed of the electron is 4.0 x 10 ^6 m/s. Calculate the magnitude and direction of the magnetic force on the electron.
Fm= qvsin θ

v= 4.0 x 10 ^6 m/s
q= 1.6 x 10 ^ -19 C
sin θ= 90
B = 0.20 T = 0.20 kg / Cs

Fm= qvsinθ
Fm= (1.6 x 10 ^ -19 C) (4.0 x 10 ^6 m/s) sin 90
Fm= The magnitude of the force is 1.3 x 10 ^ -13 N.

A straight conductor 10 cm long with a current of 15 A moves through a uniform 0.60 T magnetic field. Calculate the magnitude of the force on the conductor when the angle between the current and the magnetic field is 90 degrees.

I = 15 A
L = 10 cm
B = 0.60 T
F = ?

F= ILBsinθ
= (15 A)(0.60T)(0.10m)(sin90)
= 0.90 N

Tidal Power
Hydroelectric Generating Stations

Hydroelectric Generating Stations take advantage of the gravitational potential energy of water as it flows or falls from one level to a lower level.

• Most widely used form of renewable energy, accounting for 16 percent of global electricity generation – 3,427 terawatt-hours of electricity production in 2010
• Is expected to increase about 3.1% each year for the next 25 years

Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and the Sun and the rotation of the Earth.These tides are caused by the changes in the gravitational field in the areas that are close than the areas that are the furthest away.
The times and amplitude of the tides at a locale are influenced by the alignment of the Sun and Moon, by the pattern of tides in the deep ocean, by the systems of the oceans, and by the shape of the coastline.
The energy created by tides is an efficient source of energy for some places in the world.

The moon’s gravitational force pulls on water in the oceans so that there are bulges in the ocean on both sides of the planet. The moon pulls water towards it, and it causes the bulge towards the moon. The bulge on the other side of the earth opposite the moon is caused by the moon pulling the earth away from the water on the other side.
Tidal power,
also called
tidal energy
, is a form of hydro power that converts the energy of tides into useful forms of power - mainly electricity.

Tidal Energy is better to use as it is more predictable than solar and wind energy.

There are 3 ways to create energy:

1. Tidal Stream Generator
It uses the kinetic energy of water to power turbines. It can be built right onto bridges
2. Tidal Barrage
It makes use of the Potential energy in the difference in height between low and high tides
3. Dynamic Tidal Power
It is an untried of idea, and it proposes to use the interaction between kinetic and potential energies of the water. It is supposed to use large dams (30 - 50 km)

It eliminate green houses that contribute to the environment
It has a much greater sustainability rate than burning fossil fuels
It can affect marine life. The turbines can accidentally kill swimming sea life with the rotating blades. Sometimes the marine life will not even utilize that area since it causes harm to them
Mechanical fluids such as lubricants can leak out and be harmful to the marine life. Proper maintenance is needed always
There are only a few ideal places in the world where tidal energy can be harnessed properly

Environmental Impacts

It is a renewable resource so it is good for society and us.
Although not yet widely used, tidal power has potential for future electricity generation.
It takes about 8-12 years to complete and thus many jobs can be created.
However it costs about 100 million to create

• Satellites are artificial objects intentionally placed into orbit
• Satellites are constantly falling towards earth, due to earth’s gravity, but earth curves away from it. Thus it is free falling
• Calculations using The Law of Universal Gravitation, will help scientists determine the strength of earth’s orbit and help determine the speed the satellite needs to be launched at so it, can stay within earth’s orbit but not fall towards earth.

The world's first artificial satellite, the Sputnik 1, was launched by the Soviet Union in 1957. Since then, thousands of satellites have been launched into orbit around the Earth. Some satellites, notably space stations, have been launched in parts and assembled in orbit.
Satellites are used for a large number of purposes:
• Military observation satellites
• Civilian observation satellites
• Earth observation satellites
• Communications satellites (GPS)
• Navigation satellites
• Weather satellites
• Research satellites
• Space stations and human spacecraft in orbit are also satellites.
Satellite orbits vary greatly, depending on the purpose of the satellite,

Did you know?
3600 satellites remain in orbit and only 1000 are in use. The other satellites are flying around as space junk.
There are different types of orbits:
Altitude classifications
• Low Earth orbit (LEO): Geocentric orbits ranging in altitude from 0–2000 km (0–1240 miles)
• Medium Earth orbit (MEO): Geocentric orbits ranging in altitude from 2,000 km (1,200 mi) to just below geosynchronous orbit at 35,786 km (22,236 mi). Also known as an intermediate circular orbit.
• High Earth orbit (HEO): Geocentric orbits above the altitude of geosynchronous orbit 35,786 km (22,236 mi)


Satellites can be used to track environmental disasters and predict them (Hurricanes, and Earthquakes)

Satellites causes space debris, also known as orbital debris, space junk, and space waste. It is the collection of defunct objects in orbit around Earth.
Currently, about 19,000 pieces of debris larger than 5 cm (2.0 in) are tracked
Although most debris will burn up in the atmosphere, larger objects can reach the ground intact and present a risk.
The debris has the possible presence of hazardous chemicals.
To launch a satellite into space it can cost at least a few 100 million dollars. The more sophisticated satellites are the ones that cost around $650,000,000. It’s either the government that pays this much or private agencies who pay for satellites to be launched into space.
It may seem unethical for governments to pay for satellites when they can use the money to help the citizens in the country.
Space Debris is left in orbit. It is polluting Earth and the area around earth and its atmosphere.
Satellites could be used to spy on people and countries. It is an invasion of privacy.
Research is conducted in the ISS and other orbiting space stations. They grow cells, and organs and conduct research about how the human body works.
Allows them to connects to people around the world (GPS) : It is composed of 27 earth orbiting satellites.


• Cost is very low
• It is flexible: It can change to supply and demand. Can turn into other forms of energy
• Dams relocated 40 – 60 million people world wide
• Ruin’s plant life, displace people.
• A renewable energy source so it causes no harm to humans

• The project produces no direct waste, and has a considerably lower output level of the greenhouse gas carbon dioxide
• Renewable
• Hydroelectricity eliminates the flue gas emissions from fossil fuel combustion, including pollutants such as sulfur dioxide.
• Interrupts the flow of rivers and can harm local ecosystems
• Building large dams and reservoirs often involves displacing people and wildlife.
• Methane Emission

Most hydroelectric power comes from the potential energy of dammed water driving a water turbine and generator. The power extracted from the water depends on the volume and on the difference in height between the source and the water's outflow

Electronic Ink
This Technology is used in all electronics now.
It is supposed to revolutionize the world and make the use of paper obsolete.
• Saves 95 million trees and thus removes 98 million tons of greenhouse gases a year.
• E-Ink Displays save 60% of the energy used
• It uses 27 times less water than reading from newspapers and books (Using electronics is much better)

• The electronics that are left over will be sent to other countries as e-waste
• Electronic devices can never be able to biodegrade. After electronic waster is gone, then the harsh pollutants and chemicals can leak out.
• Electronics are made in 3rd world countries. They are shipped over to North America = Lots of fuel and harsh pollutants released into the air.
• All electronic scrap components, such as CRTs, may contain contaminants such as lead, cadmium, beryllium, or brominated flame retardants
• Airborne dioxins – one type found at 100 times levels previously measured
• Levels of carcinogens in the developing countries were above international standards
Did you know?
An estimated 50 million tons of E-waste are produced each year. The USA discards 30 million computers each year and 100 million phones are disposed of in Europe each year. The Environmental Protection Agency estimates that only 15-20% of e-waste is recycled, the rest of these electronics go directly into landfills and incinerators.[

Health Impacts
It reduces health concerns caused by pollutants or polluted air. Breathing polluted air, can affect our lungs and give us respiratory illnesses like bronchitis and asthma. Extreme exposure can lead to things such as Cancer.
It is very expensive to buy and install, thus most companies do not buy it or use it.
It is very unethical as most companies would want to earn more profit rather than save the environment
More people would want this kind of technology as it would help with the environment
This kind of technology has been adapted for in home usage as air humidifiers


Flue gas can contribute to higher CO2 emissions and thus more greenhouse gases. Climate Change will occur faster. The Flue gas can also disrupt animals as they can contaminate their habitat.

Electrostatic Precipitators can eliminate flue gas, lower the amount of CO2 emission and thus would make sure that habitats are clean.

Environmental Impacts
Electrocardiography is a trans thoracic interpretation of the electrical activity of the heart over a period of time, as detected by electrodes attached to the surface of the skin and recorded by a device external to the body. The recording produced by this noninvasive procedure is termed an electrocardiogram.

Electrocardiogram: The measurement of the difference in the heart’s muscle activity (creating electric potential).

Doctors can use the difference in the heart’s muscle activity to detect for abnormalities when comparing the beats to that of a normal healthy heart.

Health/ People:
It helps to cure and give some sort of treatment some of the different diseases.
It is one of the few machines that work to treat humanity; it can lead to the development of many other equipment
Electrocardiography is also used in fetuses records their electrical activity, and when performed as a part of monitoring in childbirth.
It is expensive; it costs $800 to at least $2000.
The overuse of electrocardiograms is more likely to supply incorrect supporting evidence for a nonexistent problem than to detect a true problem

Did you know?
An Electrocardiograms and Sonograms would not be possible without knowing about Electric Potential and Electric Fields

Electrophoresis is the motion of dispersed particles relative to a fluid under the influence of a spatially uniform electric field.
It is a procedure that enables the sorting of molecules based on size and shape
By using an electric field molecules can be made to move through a gel made of agar
The larger molecules move more slowly, while the smaller molecules move faster through the gel.
Factors that affect the migration of nucleic acids:
• Size of DNA
• Conformation of DNA
• Concentration of Ethidium bromide
• Gel concentration
• Applied Field

This technology enables scientists to study the structures and different genetic makeup of plants, animals and humans. Various different research comes out of electrophoresis like learning how evolution works, and how different disorders come about.

It protects people: DNA is unique for every single person, and thus it makes it easier for the law enforcement to capture individuals who cause harm to the greater population.


They eliminate wheels-on-rail friction by using electromagnetic force to levitate the cars
Electromagnets, mounted on the train itself and the track move the train forward through attraction between dissimilar poles and repulsion from similar poles
The train is flying encountering only the fluid friction form the air
These trains can reach tops speeds that cannot be achieved with regular trains
When the train needs to slow, the current is reversed, so that the attraction and repulsion forces are opposite to the direction of the motion.

It uses less energy than other transportation device; for example it uses 1/3 of the energy it takes for a car to run
Does not release any CO2 or other kinds of Greenhouse gases
They use superconducting electric magnets in the vehicle to propel the train up
It uses land and can cause damage to the ecosystems by taking away the natural habitat
Noise pollution from the aerodynamics

These trains are impossible to derail
Collisions are impossible; the trains are computer generated

The magnetic fields are low, so it causes no health affects

An innovative way to get to places

It is very expensive to build; it cost at least 1.2 billion in China
The operating expenses are much lower though.

The powder is not magnetic but it is attracted by a magnet, but it is attracted by a magnet and carried as whiskers by a magnetic wand.
The powder only touches the print.
The wand is a closed, hollow tube containing a magnet on a rod.
When the rod is pushed in, the magnet is located at the end of the tube and the powder clings to that end
When the rod is pulled out, the magnet is moved to the center of the tube and the powder falls out.
Then they are ready to dust the finger prints.
They are tiny iron flakes that stick to the greasy residue left by fingerprints
It gives a more accurate way to look at finger prints; it does not distort the image left by finger prints

It helps with the law and order system as recognizing fingerprints for crime and investigations become easier and more reliable
It contributes to a safe society
This method does not cause any serious health effects.

Earth's magnetic field is the magnetic field that extends from the Earth's interior to where it meets the solar wind, a stream of charged particles emanating from the Sun.
Its magnitude at the Earth's surface ranges from 25 to 65 micro Tesla
It is approximately the field of a magnetic dipole tilted at an angle of 10 degrees with respect to the rotational axis—as if there were a bar magnet placed at that angle at the center of the Earth.
However, unlike the field of a bar magnet, Earth's field changes over time because it is generated by the motion of molten iron alloys in the Earth's outer core

The magnetic field of the Earth deflects most of the solar wind. The charged particles in the solar wind would strip away the ozone layer, which protects the Earth from harmful ultraviolet rays.
Solar Wind is a stream of ionized gas that blows out from the sun at 400 km/second and that varies in intensity with the level of surface activity on the surface of the sun

Earth's magnetosphere is formed by the impact of the solar wind on the Earth's magnetic field.
Energetic particles that are on the magnetosphere are mostly electrons, but protons also make aurora. The electrons travel along magnetic field lines.
The Earth's magnetic field looks like that of a dipole magnet where the field lines are coming out and going into the Earth near the poles.
The auroral electrons are thus guided to the high latitude atmosphere.
As they penetrate into the upper atmosphere, the chance of colliding with an atom or molecule increases the deeper they go.
Once a collision takes place, the atom or molecule takes some of the energy of the energetic particle and stores it as internal energy while the electron goes on with a reduced speed.
An excited atom or molecule can return to the non-excited state (ground state) by sending off a photon, i.e. by making light.

Without the Earth’s Magnetic field, satellites that are responsible for the Earth’s communication would malfunction due to the effects of the solar winds
Cosmic Rays would penetrate all the living things and cause mutations
The high speed particles from space could kill all life
The Earth’s magnetic field also protects astronauts from the harmful radiations caused by solar winds.

Magnetic Fields in Cancer
The radiation produced by the magnetic fields has been shown to treat cancer
It has been shown the cancer cells cannot thrive in strong magnetic fields
It helps to increase a patient’s longevity.

Magnetic therapy involves placing magnets of varying sizes and strengths on the body to try to relieve pain or treat disease.
Proponents claim magnetic therapy can relieve pain caused by arthritis, headaches, migraine headaches, and stress, and can also heal broken bones, improve circulation, reverse degenerative diseases, and cure cancer.
They also claim that placing magnets over areas of pain or disease strengthens the body's healing ability.

Magnetic Therapy

Magnets can cause malfunction or damage in implantable medical devices such as pacemakers, defibrillators, or infusion pumps
Radiation can be released and thus, it can cause cells that are not affected by cancer to be affected by cancer later on in life.

Safety / Health/ Ethics
Technology, Society, Environment
Technology, Society, Environment
The Science Behind it
Technology, Society, Environment
Maglev Trains
Magnetic Finger Print Powders

The Aurora Borealis
Without it
How Earth would look like without a magnetic field
Sample Question
Sample Question
The Hubble Space Telescope follows a circular orbit, at an average altitude of 598 km above the surface of Earth.

Determine the speed needed by the HST to maintain its orbit.
Sample Question
Electrostatic Precipitators:
Sample Question
Coulomb's Law
Coulomb's Law
Electric Forces: Coulomb's Law
Laws of Electric Charge
3 Ways of Charging an Object
Millikan’s Experiment
Sample Question:
Coulomb's Law and The Law of Universal Gravitation
This was Einstein's Dream. To try and make Gravity and the Electromagnetic force into one force with one principle. This did not happen. There is a huge difference in strength between Gravity and the Electromagnetic Forces.
Scientists are now trying to make Einsteins dream come true. They are trying to unite Gravity, Electromagnetism, Weak Nuclear and Strong Nuclear force together by the simple concept of String Theory
String Theory
String Theory is a theoretical framework in which the point-like particles of particle physics are replaced by one-dimensional objects called strings. In string theory, the different types of observed elementary particles arise from the different quantum states of these strings.
Particle Accelerators
A particle accelerator is a device that uses electromagnetic fields to propel charged particles to high speeds and to contain them in well-defined beams.
There are two basic types of accelerators, known as Linear accelerators and circular accelerators. In a linear accelerator the particles travel down a long, straight track and collide with the target. In a circular accelerator particles travel around in a circle until they collide with the target.
Particle accelerators are used in a large variety of applications, including particle therapy for oncological purposes, colliders, and as synchrotron light sources for fields such as condensed matter physics.
Linear Accelerators
In linear accelerators, particles travel in a vacuum down a long, copper tube.
The electrons ride waves made by wave generators called klystrons.
Electromagnets keep the particles confined in a narrow beam.
When the particle beam strikes a target at the end of the tunnel, various detectors record the events -- the subatomic particles and radiation released.
These accelerators are huge, and are kept underground.
A Linear accelerator at the Stanford Linear Accelerator Laboratory (SLAC) in California is 3 km long.

Circular accelerators instead of using a long linear track, propel the particles around a circular track many times.
At each pass, the magnetic field is strengthened so that the particle beam accelerates with each consecutive pass.
When the particles are at their highest or desired energy, a target is placed in the path of the beam, in or near the detectors.
Circular accelerators were the first type of accelerator invented in 1929.

Circular Accelerators
Now look at this technology! It utilizes both Electricity and Magnetism!
Now look at this technology! It utilizes both Electricity and Magnetism!
Health Risks
The energetic particle beams from a particle accelerator can seriously harm those who are in contact. But since it is underground, less damage would be done to the public.
The Large Hadron Collider cost over 6 billion to make! Many large particle accelerators usually are in the billions
Environmental Risk
They are contained and are underground, so there are no risks.
Scientific Purpose
Tests the predictions of different theories of particle physics and high-energy physics, and particularly prove or disprove the existence of the theorized Higgs particle and of the large family of new particles predicted by super symmetric theories.
Over 2000 jobs were created just for this!

Particle Accelerators in YOUR house
Wow! Did you know that the cathode ray tube (CRT) of any TV or computer monitor is really a particle accelerator?
The CRT takes particles (electrons) from the cathode, speeds them up and changes their direction using electromagnets in a vacuum and then smashes them into phosphor molecules on the screen. The collision results in a lighted spot, or pixel, on your TV or computer

Electricity and Magnetism are interrelated. It seems that they seem to create one another! If there is current within a ferromagnetic metal source then a magnetic field is created!
How cool is that!

All matter is made up out of atoms.
Charged electrons orbit a dense atomic nucleus.
All that current is a moving electric charge.
That means every atom in nature is surrounded by a tiny electric current, which means all atoms have a tiny magnetic field and thus electric currents generate magnetic fields.
In most materials, these tiny atomic magnets point in every direction, and cancel out each other's effects.
This is why most materials aren't magnetic.
But in some materials these tiny magnets line up, creating a powerful magnetic field.
These materials are magnets, and are almost always metal of some kind.

Why does Current induce a Magnetic field?

The European Organization for Nuclear Research, known as CERN is an international organization whose purpose is to operate the world's largest particle physics laboratory. Established in 1954
CERN's main function is to provide the particle accelerators and other infrastructure needed for high-energy physics research – as a result, numerous experiments have been constructed at CERN following international collaborations. It is also the birthplace of the World Wide Web.


Since electricity causes magnetism it is not wise for people to live near high voltage transformers since they have magnetic fields coming out from them:
• Emerging studies suggest that electromagnetic fields that high voltage transformers may emit carry radon, which is one cause of leukemia, and that children are at greater risk than adults.
• The World Health Organization cautions that those who live within a mile of a high voltage transformer could develop neurological disorders.
• High voltage transformers may thus contribute to the risk of developing these types of cancers.

The Dangers of Electromagnetism

• The Heart is the strongest Electromagnetic Field Generator in the body
• The human heart is now documented as the strongest generator of both electrical and magnetic fields in the body.

Did you know that?
The amount of emissions made by cell phones is quite minimal. Our body is exposed to cell phone radiation while making or receiving calls. There are indications that cell phone radiation can cause a few changes in the functioning of cells. These changes are mostly temporary in nature. The functions that get affected by radiation include activation of proteins, communication between the body cells, genetic functions etc.
Effects of Cell Phone Radiation on Human Body (ELECTROMAGNETISM)

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