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- Nicolas D. Georganas
- University of Ottawa
- Canada
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- 600 BC- Electricity discovered by the first known Greek engineer,
mathematician, scientist and philosopher Thales of Miletus – „the first
philosopher of Western Civilization“, being the only philosopher before
Socrates to be among the Seven Sages
- When amber ( in Greek,
ελεκτρον) is rubbed with fur,
it acquires the ability to attract other materials such as feathers or
bits of straw. The force, first observed by Thales, is very weak.
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- 2000 years after Thales, William Gilbert, court physician to Queen
Elizabeth I, showed that many
other materials exhibit this small force. He coined the word “electric”
(after the Greek word for amber –electron, or
ελεκτρον) for this phenomenon.
- 1600 - publishes his great study of magnetism, "De
Magnete"--"On the Magnet". It gave the first rational
explanation to the mysterious ability of the compass needle to point
north-south: the Earth itself was magnetic.
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- 1745 - Pieter van Musschenbroek invents the Leyden jar, or capacitor,
and nearly kills his friend Cunaeus!
- The same device was invented independently by Georg von Kleist at about
the same time, but not published.
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- 1747 - worked with static charges in the air and noted that that their
existence suggested the existence of an electrical fluid that could
possibly be composed of particles.
- 1747 - invents the theory of one-fluid electricity. He
proposes the principle of conservation of charge and calls the fluid
that exists and flows ``positive''. He also discovers that electricity
can act at a distance in situations where fluid flow makes no sense.
- 1750 - discovered that lightning was the same as electrical discharges,
and proposed the idea of lightning rods that would draw this charge away
from homes, making them safer and less prone to fires. In 1752, Franklin
reported the results of his famous kite experiments to the Royal Society
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- Henry Cavendish- English chemist and physicist who was shy and
absent-minded. He was terrified of women, and communicated with his
female servants by notes!
- ca 1775 - invents the idea of capacitance and resistance
(the latter without any way of measuring current other than the level of
personal discomfort). But being indifferent to fame he is content to
wait for his work to be published by Lord Kelvin, 100 years later, in
1879.
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- 1780 - Luigi Galvani causes dead frog legs to twitch with
static electricity, then also discovers that the same twitching can be
caused by contact with dissimilar metals. His followers invent another
invisible fluid, that of ``animal electricity'', to describe this
effect.
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- 1785 - Charles Augustin de Coulomb uses a torsion balance to
verify that the electric force law is inverse square.
- proposed a combined fluid/action-at-a-distance theory but with two
conducting fluids instead of one.
- discoverd that the electric force near a conductor is proportional to
its surface charge density and makes contributions to the two-fluid
theory of magnetism.
- examined perfect conductors and dielectrics. He suggested that there was
no perfect dielectric, proposing that every substance has a limit above
which it will conduct electricity.
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- 1793 - Alessandro Volta makes the first batteries and
following the experiments of Galvani, who was a friend of his, argues
that animal electricity is just ordinary electricity flowing through the
frog legs under the impetus of the force produced by the contact of
dissimilar metals and has nothing to do with the tissue.
- 1800 - he discovers the Voltaic
pile (dissimilar metals separated by wet cardboard) which greatly
increases the magnitude of the effect.
- The invention of the battery lifted Volta's fame to its pinnacle. He was
called to France by Napoleon in 1801 for a kind of "command
performance"of his experiments. He received many medals and
decorations, including the Legion of Honor, and was even made a count
and, in 1810, a senator of the kingdom of Lombardy.
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- Considered as „the Newton of Electricity“
- 1820 -one week after hearing of Oersted's discovery that electric
current in a wire causes a compass needle to orient itself perpendicular
to the wire, shows that parallel currents attract each other and that
opposite currents attract too.
- 1825 - publishes his
collected results on magnetism. His expression for the magnetic field
produced by a small segment of current is different from that which
follows naturally from the Biot-Savart law
- It is unfortunate that electrodynamics and relativity decide in favor of
Biot and Savart rather than for the much more sophisticated Ampere,
whose memoir contains both mathematical analysis and experimentation,
artfully blended together.
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- 1807 - He shows that the essential element of Volta's pile
is chemical action, since pure water gives no effect. He argues that
chemical effects are electrical in nature.
- 1821 - He shows that direct current is carried throughout
the volume of a conductor. He also discovers that resistance is
increased as the temperature rises.
- Davy twice opposed the election of Faraday to fellowship in the Royal
Society; probably envious of his former assistant!
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- Michael Faraday is known for his pioneering experiments in electricity
and magnetism. Many consider him the greatest experimentalist who ever
lived
- 1812 - a bookbinder‘s apprentice, writes to Sir Humphrey Davy
asking for a job as a scientific assistant. Davy interviews Faraday and
finds that he has educated himself by reading the books he was supposed
to be binding. He gets the job.
- 1831 - shows that
changing currents in one circuit induce currents in a neighboring
circuit. He discoveres electromagnetic induction. He explained that it
was necessary to have a change in a magnetic field to create current,
and that its mere presence was not enough.
- 1833 - begins work on the relation of electricity to
chemistry. He concludes after a series of experiments, ``...there is a
certain absolute quantity of the electric power associated with each
atom of matter.''
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- 1834 - discovers self inductance.
- 1837 - discovers the idea of the dielectric constant.
- 1838 - shows that the effects of induced electricity in
insulators are analogous to induced magnetism in magnetic materials.
- 1838 - discovers Faraday's dark space, a dark region in a
glow discharge near the negative electrode.
- 1841 - completely exhausted by his efforts of the previous 2
decades, he rests for 4 years.
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- 1845 - discovers that the plane of polarization of light is
rotated when it travels in glass along the direction of the magnetic
lines of force produced by an electromagnet (Faraday rotation).
- 1846 - discovers diamagnetism.
- 1846 - inspired by his discovery of the magnetic rotation of
light, writes a short paper speculating that light might be
electro-magnetic in nature. He thinks it might be transverse vibrations
of his beloved field lines.
- 1855 - Faraday retires, living quietly in a house provided
by the Queen until his death in 1867.
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- 1827 Joseph Henry discovered the concept of electrical inductance. He
also built one of the first electrical motors.
- Henry appears to have discovered the principle of electromagnetic
induction independently of Michael Faraday, but because Faraday
published his results before Henry, he is credited with the discovery.
- widely considered the foremost American scientist of the 19th century.
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- 1826 - establishes the result now known as Ohm's law. V=IR
seems a pretty simple law to name after someone, but the importance of
Ohm's work does not lie in this simple proportionality. What Ohm did was
develop the idea of voltage as the driver of electric current. He
reasoned by making an analogy between Fourier's theory of heat flow and
electricity. In his scheme, temperature and voltage correspond as do
heat flow and electrical current.
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- 1848-9 - Gustav Kirchoff extends Ohm's work to conduction in
three dimensions, gives his laws for circuit networks, and finally shows
that Ohm's ``electroscopic force'' which drives current through
resistors and the old electrostatic potential of Lagrange, Laplace, and
Poisson are the same.
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- 1857 - Gustav Kirchoff derives the equation of telegraphy
for an aerial coaxial cable where the inductance is important and
derives the full telegraphy equation.
- He recognizes that when the resistance is small, this is the wave
equation with propagation speed
which turns out to be very close to the speed of light.
- Kirchoff notices the coincidence, and is thus the first to discover that
electromagnetic signals can travel at the speed of light.
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- 1850 - William Thomson (Lord Kelvin) invents the idea of magnetic
permeability and susceptibility
- 1853 - He uses Poisson's magnetic theory to derive the
correct formula for magnetic energy .
- 1853 - Thomson gives the theory of the RLC circuit providing
a mathematical description for the observations of Henry.
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- 1854 - Thomson, in a letter to Stokes, gives the equation of
telegraphy, ignoring the inductance.
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- 1861 - publishes a mechanical model of the electromagnetic
field. Magnetic fields correspond to rotating vortices with idle wheels
between them and electric fields correspond to elastic displacements,
hence displacement currents.
- This addition completes Maxwell's
equations and it is now easy for him to derive the wave equation and to
note that the speed of wave propagation was close to the measured speed
of light.
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- 1864 - Maxwell reads a memoir before the Royal Society in
which the mechanical model is stripped away and just the equations
remain.
- He wants to present the predictions of his theory on the subjects of
reflection and refraction, but the requirements of his mechanical model
keep him from finding the correct boundary conditions, so he never does
this calculation
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- 1873 - publishes his Treatise on Electricity and Magnetism,
which discusses everything known at the time about electromagnetism from
the viewpoint of Faraday.
- His own theory is not very thoroughly discussed, but he does introduce
his electromagnetic stress tensor in this work, including the
accompanying idea of electromagnetic momentum.
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- 1870 - Helmholtz derives the correct laws of reflection and
refraction from Maxwell's equations. Once these boundary conditions are
taken, Maxwell's theory is just a repeat of MacCullagh's theory. The
details were not given by Helmholtz himself, but appear rather in the
inaugural dissertation of H. A. Lorentz.
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- Hertz opened the way for the development of radio, television, and radar
with his discovery of electromagnetic waves between 1886 and 1888. James
Clerk Maxwell had predicted such waves in 1864.
- 1888 - discovers that oscillating sparks can be produced in
an open secondary circuit, if the frequency of the primary is resonant
with the secondary.
- He uses this radiator to show that electrical signals are propagated
along wires and through the air at about the same speed, both about the
speed of light.
- 1889 - Hertz gives the theory of radiation from his
oscillating spark gap.
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- 1892 - presents his electron theory of electrified matter
and the aether. This theory combines Maxwell's equations, with the
source terms and with the Lorentz force law for the
acceleration of charged particles.
- Lorentz gives the modern theory of dielectrics, and also includes the
effect of magnetized matter.
- 1902 - Nobel Prize, with his student Pieter Zeeman
- 1904 - Lorentz gives his electron-collision theory of
electrical conduction
- 1905 - Albert Einstein completes Lorentz's work on
space-time transformations and relativity is born.
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- Alexander Graham Bell, a Scotish teacher and inventor, worked with the
deaf and became fascinated with studying sound.
- 1875 - Bell discovered a way to convert sound waves to an undulating
current that could be carried along wires. This helped him invent the
telephone. The first phone conversation was an inadvertent one between
Bell and Watson, his assistant in the next room. After spilling some
acid, Bell said “Mr. Watson, come here. I want you.” He patented his
device the same year.
- After inventing the telephone, Bell continued his experiments in
communication. He invented the photophone-transmission of sound on a
beam of light, the precursor of fiber-optics.
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- the most prolific inventor of all time, Thomas Edison held an amazing
1,093 patents!
- 1879 - Thomas Edison demonstrated his most famous invention: the first
practical incandescent electric lamp
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- 1883 - Nikola Tesla invented a practical AC motor
- Several years later , George
Westinghouse bought the patents to the Tesla motor and set up an AC
power system.
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- Radio began in 1888 when German physicist Heinrich Hertz demonstrated
the existence of radio waves (the unit of measurement for radio wave
frequency was named in his honor). Radio waves, also called
electromagnetic waves, have the lowest frequency and the longest
wavelength of any type of radiation in the electromagnetic spectrum. In
a classroom experiment, Hertz made a condenser that produced these
waves. Hertz didn’t think his experiment had any practical applications,
but another man did—Italian Guglielmo Marconi.
- Nobel Laureate in Physics (1909)
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- Marconi thought electromagnetic waves could be used to transmit signals.
He was right. At first, Marconi was able to transmit Morse Code only a
couple of miles. But in 1901 he built a transmitter strong enough to
send messages across the Atlantic Ocean. This was the beginning of
wireless communication.
- Radio became a new way of sending Morse Code and Marconi created a very
successful company that did just that. One of the industries to benefit
most from Marconi’s work was the shipping industry.
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- Finally, a Canadian!
- the first person to prove that voices and music could be heard over the
air without wires. Yet some books ignore him, others mistakenly call him
an American!
- 1906 - the first public radio broadcast of music and voice on Christmas
Eve
- developed amplitude modulation, or as we call it today, AM.
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- 1884 - German engineering student, Paul Nipkow proposed and patented the
world's first electromechanical television system. He devised the notion
of dissecting the image and transmitting it sequentially. To do this he
designed the first television scanning device
- 1928 - performed the first wired image transmission
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- 1947 – Invention of the transistor at Bell Labs
- Nobel prize 1956
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- 1946- UPenn scientists credited with the invention of the Electronic
Numerical Integrator And Computer (ENIAC), the first general-purpose
electronic digital computer, completed.
- Scientists across the ocean in England were working on their own machine
a couple of years before ENIAC was built. Their computer, the Colossus,
was used to decipher German code during World War II. But the Colossus
was designed exclusively for code breaking
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- 1958 – Invention of the LASER (Light Amplification by Stimulated Emission
of Radiation ) at Bell Labs
- 1960 – patent
- 1960- First operating laser built by Theodore Maiman
- 1964 –Nobel Prize for Townes
- 1981- Nobel Prize for Schawlow
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- IT is moving very fast with advances in:
- Computer Science and Software Engineering
- Wireless and Optical Communications
- Ubiquitous Computing and Communications
- Nanotechnologies amd Mechatronics
- Power Engineering
- Physics, Chemistry & Chemical Engineering
- ...
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- 1958 - After USSR launches Sputnik, first artificial earth satellite,
US forms the Advanced Research Projects Agency (ARPA), the following
year, within the Department of Defense (DoD) to establish US lead in
science and technology applicable to the military
- 1961 - First published work on packet switching (“Information Flow in
Large Communication Nets”, Leonard Kleinrock, MIT graduate student)
- 1964 - Other independent work in
packet switching at RAND Corporation (Paul Baran) and National Physics
Laboratory in England (Donald Davies)
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- 1966 - Lawrence Roberts (colleague of Kleinrock from MIT) publishes
overall plan for an ARPAnet, a proposed packet switch network
- 1968 -ARPA awards contracts for four nodes in ARPANET to:
- UCLA (Network Measurement),
- Stanford Research Institute (Network Information Center),
- UCSB (Interactive Mathematics) and
- U Utah (Graphics)
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- 1967-1972
- Vint Cerf, graduate student in Kleinrock’s lab, works on application
level protocols for the ARPANET (file transfer and Telnet protocols)
- 1974
- Robert Kahn and Vint Cerf develop a protocol (TCP) to connect networks
without any knowledge of the topology or specific characteristics of
the underlying nets
- 1978
- TCP split into TCP and IP protocols
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- 1990
- Tim Berners-Lee, at CERN, develops hypertext system, called
“WorldWideWeb”, with initial versions of HTML and HTTP and first GUI web
browser
- Web causes an astonishing growth in Internet use
- People on the Internet
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Notes
