What is Reality ?
Since ancient time, philosophers, scientists and
poets have wondered what our physical reality actually consists of. It turns
out that nearly all aspects of our apparent physical existence are manifestations
of electromagnetic forces and energies. This electromagnetic force is what
gives material objects the illusion of solidity even though they are composed
of 99.999% empty space. When a hammer strikes a nail, the actual protons,
neutrons and electrons dont touch each other, it is the electromagnetic
force fields of the hammer and the nail that bang together. The latent force
of electromagnetism may be mathematically described by a field of
vectors, hence the term force field.
Then along came Maxwell
By the late 19th century, many scientists had
discovered laws of electricity and magnetism now familiar to us; Faraday,
Ohm, Ampere, Volta, Franklin and others. James Clerk Maxwell, a young
Scottish mathematician, took upon himself to forge these fragments into
a set of powerful interlocking equations which totally describe the behavior
of the electromagnetic force.
Maxwell quickly realized that magnetism,
electricity and light were different aspects of the same force discribed
by his vector equations. Over a hundred years later, the Maxwell equations
are the cornerstone of antenna theory, optics, physical chemistry and
lie at the very root of most physical phenomena we perceive. Light, electricity,
magnetism, radio, microwaves, x-rays, chemical bonds, combustion, mechanical
properties of solids, liquids and gasses and many other physical phenomena
are manifestations of the electromagnetic force. It has been well said
that all the laws of classical physics may be derived from Maxwells equations.
Maxwells Equations in
Integral Form
A
controversy still overhangs the Maxwell Equations. The "Maxwell Equations"
used today (shown above) are not the originals. Maxwell originally used
many equations, including expressions in quaternion mathematics when he
correctly proved magnetism and light to be aspects of the same force,
in his paper "A Dynamical Theory of the Electromagnetic Field" in October
of 1864. The familiar form of four interlocking vector equations used
today, in either differential or integral form (above shown in integral
form) are actually a simplification developed later by Oliver Heaviside
and William Gibbs. Heaviside (of Kennely-Heaviside Layer fame, the original
name of the ozone layer or ionosphere) declared his dislike for Maxwell's
quaternions, and ridiculed Maxwells notion of magnetic field 'idlers'.
Maxwell himself emphasized the idler notion was not to be taken literally,
but was necessary for visualizing a valid mathematical concept. Yet the
self educated Heaviside stripped Maxwells work of its quaternion terms
and reduced it to the four simplified equations used today in the design
of things like cellular phones, radar antennas and invisible airplanes.
Some
folks, however, believe Maxwells original work taken in its entirety would
have unified gravity as well, a theory known as 'electrogravitics' which
would indeed have vast implications. Einstein used the simplified Heaviside
forms in his Special and his General Theories of Relativity, thus missing
the opportunity to unify gravity. Proponents of Electrogravitics hope
the missing peices hold the keys to gravity generators, antigravity, gravity-energy
conversion and the like.
Physics Today
Modern physicists believe in the existence of four
fundamental forces in nature. In order of increasing strength they are:
gravitational, weak nuclear, electromagnetic, and strong nuclear forces.
It has been shown that the electromagnetic, weak and strong nuclear forces
are aspects of the same force, that is, the three strongest forces have
been unified mathematically. The holy grail of modern physics is
the mathematical unification of all four forces.
Establishment physicists
believe that at higher energies, a single fundamental force will be shown
which acts as four separate forces at lower energies. Big Science experiemnts
have unified three forces, but physicists now believe the energy required
to unify gravity (the Grand Unification Energy) is beyond anything which
could be produced on earth. Physics is now turning to Cosmology, hoping
to see clues to the Grand Unification in high energy processes involving
black holes, quasars or even the afterglow of the beginning of the universe.
The Gospel According
to Heaviside
In classical electromagnetics, the four Maxwell
equations are expressed in terms of four vectors. They are: electric field,
E,
electric flux,D,
magnetic fieldH,
and magnetic flux,B.
The equations are interlinked because each vector force is described in
terms of another. The equations are further linked by two continuity
conditions.
Maxwell's equations
state that when an electric field moves, it creates a magnetic vortex,
a kind of swirl or wake in spacetime. Likewise, when a magnetic field
moves, it creates an electric vortex. Light, x-rays, radio waves and the
like are merely ripples in our spacetime continuum, where the electric
and magnetic aspects of the force travel together as electromagnetic
waves which propagate at the speed of light.
The top half of this illustration shows how
the force field vectors make up a slice of an electromagnetic plane wave
which travels in space. The lower half shows how the force field vectors
are often simply pictured in amplitude.
| Region |
Approx Range (meters/hertz) |
Specific Range |
Radio
Waves
 |
104 - 10-2
m/104 - 1010 Hz |
|
| ultra-low frequency (ULF) |
3 - 30 Hz |
| extremely low frequency (ELF) |
30 - 300 Hz |
| voice frequencies (VF) |
300 Hz - 3 kHz |
| very low frequency (VLF) |
3 - 30 kHz |
| low frequency (LF) |
30 - 300 kHz |
| medium frequency (MF) |
300 kHz - 3 MHz |
| high frequency (HF) |
3 - 30 MHz |
| very high frequency (VHF) |
30 - 300 MHz |
| ultra high frequency (UHF) |
300 MHz - 3 GHz |
| super high frequency (SHF) |
3 - 30 GHz |
| extremely high frequency (EHF) |
30 - 300 GHz |
| shortwave |
see MF, HF |
| television |
see VHF, UHF |
| microwave |
30 cm - 1 mm/1-300 GHz |
Infrared
 |
10-3 - 10-6
m/1011 - 1014 Hz |
|
| far |
1000-30 um |
| middle |
30-3 um |
| near |
3-0.75 um |
Visible
 |
5x10-7 m/2x1014
Hz |
|
| red |
770-622 nm |
| orange |
622-597 nm |
| yellow |
597-577 nm |
| green |
577-492 nm |
| blue |
492-455 nm |
| violet |
455-390 nm |
Ultraviolet
 |
10-7 - 10-8
m/1015 - 1016 Hz |
|
| UV-A (least harmful) |
400-315 nm |
| UV-B (more harmful, absorbed
by ozone) |
315-280 nm |
| UV-C (most harmful, but all
absorbed by air) |
280-100 nm |
| near UV ("black light") |
400-300 nm |
| far UV |
300-200 nm |
| vacuum UV |
200-100 nm |
X
ray
 |
10-9 - 10-11
m/1017 - 1019 Hz |
|
Gamma ray
|
10-11 - 10-13
m/1019 - 1021 Hz |
|
The whole list of wavelengths for electromagnetic
waves—from the very short to the very long—are called the
Electromagnetic Spectrum. Wavelengths Starting with the long wavelengths,
the list of waves in the electromagnetic spectrum consist of: Radio
waves (longest wavelength - 1 mile or 1.5 kilometer or more) TV
waves Microwaves Infra-red waves Light waves (medium
length - 1/1000 centimeter) Ultraviolet rays X-rays
Gamma rays (shortest wavelength - 1/10,000,000 centimeter) Uses
Do any of those waves sound familiar? They should, since many are used
in your everyday devices. Radio and television waves are the longest
usable waves. Microwaves are used in telecommunication as well as
for cooking food. Infra-red waves are barely visible. They are the
deep red rays you get from a heat lamp. Light waves are the radiation
you can see with your eyes. Ultraviolet rays are what give you sunburn
and are used in "black lights" that make object glow. X-rays go
through the body and are used for medical purposes. Gamma rays are
dangerous rays coming from nuclear reactors and atomic bombs.
Electromagnetic Waves
Although they seem different, such waveforms as radio
waves, microwaves, x-rays, and even visible light are all waves of energy
called electromagnetic waves. They are part of the electromagnetic spectrum,
and each has a different range of wavelengths which cause they waves to
affect matter differently. For example, the set of wavelengths called radio
waves affects matter differently than do the set of wavelengths called microwaves.
Questions you may have about this curious waveform are: How are electromagnetic
waves created? What are their characteristics? What is the electromagnetic
spectrum? What are some sources of these waves? How are these
waves detected or used?
Creating electromagnetic waves
You saw in that there is an electrical field
between electrical charges, causing things to attract or repel. When electrons
move, they also create a magnetic field. Now, when the electrons move back
and forth, the fields change together, forming an electromagnetic wave,
according to the motion of the electron. For example, in Alternating Current
Electricity it is stated that that household AC electricity alternates at
60 cycles per second (Hertz). Thus, AC electricity creates waves that are
a combination of electrical field waves and magnetic field waves. This is
just one example of electromagnetic waves. Their discovery has impacted
our lives in many ways.
Characteristics of electromagnetic
waves
Electromagnetic waves are transverse waves, similar
to water waves in the ocean or the waves seen on a guitar string. This is
as opposed to the compression waves of sound. All waves have amplitude,
wavelength, velocity and frequency.
Velocity
The velocity of electromagnetic waves in a vacuum
is approximately 186,000 miles per second or 300,000 kilometers per second,
the same as the speed of light. When these waves pass through matter, they
slow down slightly, according to their wavelength.
Wavelength
The wavelengths of electromagnetic waves go from extremely
long to extremely short and everything in between. The wavelengths determine
how matter responds to the electromagnetic wave, and those characteristics
determine the name we give that particular group of wavelengths.
Sources of electromagnetic radiation
Electromagnetic radiation is emitted from all matter
with a temperature above absolute zero. Temperature is the measure of the
average energy of vibrating atoms and that vibration causes them to give
off electromagnetic radiation. As the temperature increases, more radiation
and shorter wavelengths of electromagnetic radiation are emitted.
Sources of long wavelengths
Microwaves, radio, and television waves are emitted
from electronic devices. Sparks and alternating current cause vibrations
at the appropriate frequencies.
Sources of visible light
Visible light is emitted from matter hotter than about
700 degrees Celsius. This matter is said to be incandescent. The sun, a
fire, and the ordinary light bulb are incandescent sources of light. As
the element in an electric stove gets warms, it gives off infrared radiations,
and then when it gets hotter than 700 degrees, it starts to glow. Visible
light is being emitted from the hot element.
Detectors of electromagnetic
radiation
There are a number of different types of detectors
of electromagnetic radiation. We know the common ones for detecting visible
light: the eye, camera film, and the detectors on some calculators. Your
skin can also detect both visible light and infra-red heat rays. Electronic
devices are necessary to detect most of the longer waves, such as radio
waves. Special film can detect shorter wavelengths such as X-rays.
Visible Light
Have you ever wondered how a camera works? Or why
you need a flashlight to see in the dark? Or how a magnifying glass can
make things look bigger? Or why a rainbow looks so colorful? Most of you
have seen these phenomena and many of you have wondered what caused them
and why they behave the way they do. The explanations to these phenomena
aren't as complicated as you may think. They can be explained by learning
about light. In fact, it is exciting to be able to learn about these things
and to comprehend them. Questions you may have about visible light
include: Exactly, what is visible light? In what ways can
light be detected? How is light created? How does light go
through glass? What are light's wave characteristics?
What is visible light?
Visible light is light that we can see. There are
light waves--such as infra red and ultraviolet--that are beyond the range
of detection by the human eyes. Light is an electromagnetic wave. Since
it is a waveform, it has the characteristics of waves. The wavelength of
the light determines whether or not your eyes can detect it.
Detecting light
The most obvious way you detect visible light is with
your eyes. There are other ways and devices used to detect rays of light.
You can feel the heat caused by light on your skin. The film in a camera
detects light and turns it into the images you see in photographs. Another
device that detects light is a solar powered calculator or other device
that uses a solar cell.
Light causes changes
Light can cause chemical changes in some materials.
One example is how the sun will fade the colors in your furniture. Photographic
film changes its chemical characteristics according to how much light strikes
it. Light can also cause electrical changes to occur in some materials.
For example, a solar cell creates electricity from light. The retina in
your eyes goes through chemical changes that creates electrical impulses
when light strikes it.
What effect does light have on
objects it strikes?
There are a number of effects that light has on objects
it strikes: When light strikes an object, it can heat up that object.
An example of this is when sunshine warms your skin. Light can cause
electricity to be generated, like with a solar-powered calculator.
Light can cause chemical changes, as seen when plants use light to grow.
This is also what happens when colors fade from sunlight or when photo-sensitive
sunglasses get darker in bright light. Can you think of any other
effects light can have on objects?
What happens to light itself
when it strikes an object?
When light strikes an object, some of it can be absorbed.
That is how an object gets warm when exposed to sunlight. Light is also
reflected off of objects. Otherwise, we wouldn't be able to see those objects.
Also, it is reflected off shiny objects, such as a mirror. Finally, light
can pass right through some materials such as glass.
Creating light
Visible light is created when an object becomes sufficiently
hot. For example, the Sun is so hot that is gives off visible light. Likewise,
a fire is hot, as is the filament in a light bulb. As the burner on an electric
stove gets hot, it first gives off invisible infra red light, then deep
red and finally orange or yellow light. Some chemical or electrical reactions
can create light without getting hot. A good example of that is the light
from a firefly. We can see that light comes from the sun, moon, and stars.
It comes from fires, light bulbs, lightning, as well as from hot things
that are glowing. Can you think of any other sources of light?
Personal observations concerning
light
The first thing we want to do is to take a closer
look at light in the world around us. What are some other properties
of light you've observed or experienced? A sample listing of properties
of light include: Light consists of different colors, as seen in a
rainbow. It can have different brightness intensities. Light
can "light up" an object in the dark Light is reflected off that object
to illuminate it. It can be focused by a lens or curved mirror.
Light seems to travel in rays or beams. Light gets someplace almost
instantaneously. Its speed is very fast. Can you think of any other
interesting properties or characteristics of light? From these personal
observations, can you better explain light? By going through all these observations
about light, we have a better idea of all the different characteristics
of it. But is there more to know? Can we cause other effects? Can we develop
a model or a theory that we can use to predict other characteristics and
uses?
Light is an electromagnetic wave
Light is considered an electromagnetic wave. Whereas
sound consists of wave motion of air or other objects, light is consists
of wave motion of both electric and magnetic force fields together. Electromagnetic
waves are transverse waves, as opposed to sound waves which are compression
waves..
Characteristics of light waves
Just like other wave forms, light waves have the characteristics
of wavelength. amplitude, and velocity. Frequency is denoted by the equation:
velocity = frequency x wavelength.
Amplitude of light wave
The amplitude of a light wave corresponds to how bright
the light is. This is similar to how loud a sound is. Photometry is the
science of measuring light intensity. Photographers use photometers to tell
how bright the light is.
Wavelength of light
Just as different wavelengths of sound are detected
as different notes or pitches, different wavelengths of visible light are
detected as different colors.
White light and the spectrum
of colors
Normally, the light you see from a bright object,
such as a light bulb, is considered white light. In reality, it consists
of the colors that you see in a rainbow. This is called the visible spectrum.
These colors are: red, orange, yellow, green, blue, indigo, and violet.
The spectrum of colors can be easily remembered by the name: ROY G. BIV.
Light you can't see Also, just as there are sounds beyond the range of human
hearing -- such as the very high pitches that dogs can hear or the extremely
low notes that elephants can hear but humans can't -- there are also wavelengths
of light both shorter and longer than the visible colors that humans can
sense. All of the wavelengths from very long to visible to very short make
up the electromagnetic spectrum.
The Velocity of light
Light travels
extremely fast. The speed or velocity of light in a vacuum is 186,000
miles per second or 300,000 kilometers per second. Thus, for short distances,
light travels almost instantaneously. That was why it was so difficult
to measure the speed of light for many years. Velocity in different
substances Light travels at slower speeds in different substances. Its
velocity is somewhat related to the density of the material and it slower
in more dense materials. Thus the speed of light in glass is only 75 %
of its speed in air. (This is just the opposite of sound waves). The different
velocities in different materials results in the effect of refraction,
which will be explained later.
Velocity for different wavelengths
Although all wavelengths travel at the same speed
in a vacuum, the speed of light varies for the different wavelengths when
it passes through a substance. Red light will move through glass at a slower
speed than blue light. This difference in speed results in the effect of
dispersion, which will be explained later. Sources of light or electromagnetic
radiation Electromagnetic radiation is emitted from all matter with a temperature
above absolute zero. As the temperature increases, more radiation and shorter
wavelengths of electromagnetic radiation are emitted.
Sources of visible light
Visible light is emitted from matter hotter than about
700 degrees C, and this matter is said to be incandescent. The sun, a fire,
and the ordinary light bulb are incandescent sources of light. Materials
that light passes through Light easily passes through air and glass. They
are called transparent. It is obvious that it doesn't pass through
materials like steel or wood. There are some materials that only allow some
of the light to pass through them. If only a percentage of the light can
pass through, the material is called translucent. Some materials only allow
selected wavelengths to pass through. Colored glass may block some colors,
while allowing only one or two specific wavelengths to pass through it.
Special characteristics
of light
A wave model of light can be used to explain diffraction,
interference, and polarization, all of which provide strong evidence for
the wavelike nature of light. Diffraction Diffraction is the bending
of light around the edge of an object or spreading of light in an arc after
passing through a tiny opening. Did you ever see waves hit a breakwater
and then sort of go around the obstacle at the edges? The same thing happens
with light at edges. Another example of diffraction can be seen by looking
at the tiny grooves in a phonograph record. Look at a sharp angle, and you
should see how light is spread into various colors by the diffraction.
Interference
Since light is a wave motion, it is possible that
if the waves are out of phase with each other, that they could cancel out
each other. Another example is that is waves are of slightly different wavelength,
they could cause "beat frequencies." This is similar to hold two tuning
forks that are slightly different near each other. They produce a throbbing
sound or slow beats. Interference occurs when light passes through
two small slits or holes and produces an interference pattern of bright
lines and dark zones. Oil slicks on a wet pavement are caused by the interference
of the light passing through and reflecting off the ultra-thin oil film.
Polarized light
Polarized light is light that is allowed to vibrate
in only one direction. This is similar to trying to vibrate a rope that
passes through a picket fence: the rope can only vibrate is a direction
parallel to the pickets. Polarized light vibrates in one direction only,
in a plane. Light can be polarized by certain materials, by reflection,
or by scattering. Polarization can only be explained by a transverse wave
model. Polaroid sunglasses are used to cut down glare. They filter
out light that is reflected off surfaces, but allow the other to pass through.
Dual nature of light
Today, the properties of light are explained by a
model that incorporates both the wave and the particle nature of light.
Light is considered to have both wave and particle properties and is not
describable in terms of anything known in the everyday-sized world.
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