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A Brief History of Electricity


Albert Einstein. Some Electrical Inventors. Samuel F. B. Morse (Telegraph) ... Albert Einstein (1879 1955) ... Bodies,' by Albert Einstein, Annalen der ... – PowerPoint PPT presentation

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Title: A Brief History of Electricity

A Brief History of Electricity
  • Lecture L0.0

Some Electrical Pioneers
  • Ancient Greeks
  • William Gilbert
  • Pieter van Musschenbroek
  • Benjamin Franklin
  • Charles Coulomb
  • Alessandro Volta
  • Hans Christian Oersted

Some Electrical Pioneers (cont.)
  • Andre-Marie Ampere
  • Michael Faraday
  • Joseph Henry
  • James Clerk Maxwell
  • Heinrich Hertz
  • J. J. Thomson
  • Albert Einstein

Some Electrical Inventors
  • Samuel F. B. Morse (Telegraph)
  • Guglielmo Marconi (Wireless telegraph)
  • Thomas Edison (Electric lights …..)
  • Nikola Tesla (A.C. generators, motors)
  • John Bardeen and Walter Brattain
  • Transistor
  • Jack Kilby and Robert Noyce
  • Integrated Circuit

Ancient Greeks Static Electricity
Rub amber with wool. Amber becomes negatively
charged by attracting negative charges
(electrons) from the wool. The wool becomes
positively charged. The amber can then pick up a
feather. How?
William Gilbert (1544-1603)
English scientist and physician to Queen
Coined the word electricity from the Greek word
elektron meaning amber.
In 1600 published "De Magnete, Magneticisque
Corporibus, et de Magno Magnete Tellure" ("On the
Magnet, Magnetic Bodies, and the Great Magnet of
the Earth").
Showed that frictional (static) electricity
occurs in many common materials.
Pieter van Musschenbroek (1692 1761)
Dutch physicist from Leiden, Netherlands, who
discovered capacitance and invented the Leyden
Leyden jar (also called condenser)
Ref http//chem.ch.huji.ac.il/eugeniik/history/m
Leyden Jars
700 pF, 175 KV
Q C x V 700 x 10-12 x 175 x 103
1.225 x 10-4 coulombs
No. of electrons 1.225 x 10-4 coulombs / 1.6 x
10-19 coul/elec 7.66 x 1014 electrons
http//www.alaska.net/natnkell/leyden.htm http//
Benjamin Franklin (1706 1790)
Conducted many experiments on static electricity
from 1746 1751 (including his lightning
experiment) and became famous throughout Europe
by describing these experiments in a series of
letters to Peter Collinson.
Charles Coulomb (1736 1806)
Using a torsion balance Coulomb in 1784
experimentally determined the law according to
which charged bodies attract or repel each other.
Coulombs Law
Unit Newton meter / coulomb2 volt meter /
Alessandro Volta (1745 1827)
Interpreted Galvanis experiment with decapitated
frogs as involving the generation of current
flowing through the moist flesh of the frogs leg
between two dissimilar metals. Argued with
Galvani that the frog was unnecessary.
In 1799 he developed the first battery (voltaic
pile) that generated current from the chemical
reaction of zinc and copper discs separated from
each other with cardboard discs soaked in a salt
Hans Christian Oersted (1777 1851)
In 1820 he showed that a current produces a
magnetic field.
Ref http//chem.ch.huji.ac.il/eugeniik/history/
André-Marie Ampère (1775 1836)
French mathematics professor who only a week
after learning of Oersteds discoveries in Sept.
1820 demonstrated that parallel wires carrying
currents attract and repel each other.
A moving charge of 1 coulomb per second is a
current of 1 ampere (amp).
Michael Faraday (1701 1867)
Self-taught English chemist and physicist
discovered electromagnetic induction in 1831 by
which a changing magnetic field induces an
electric field.
A capacitance of 1 coulomb per volt is called a
farad (F)
Joseph Henry (1797 1878)
American scientist, Princeton University
professor, and first Secretary of the Smithsonian
Built the largest electromagnets of his day
Discovered self-induction
Unit of inductance, L, is the Henry
James Clerk Maxwell (1831 1879)
Born in Edinburgh, Scotland Taught at Kings
College in London (1860-1865) and was the first
Cavendish Professor of Physics at Cambridge
Provided a mathematical description of Faradays
lines of force.
Developed Maxwells Equations which describe
the interaction of electric and magnetic fields.
Predicted that light was a form of
electromagnetic waves
From a long view of the history of mankind -
seen from, say, ten thousand years from now -
there can be little doubt that the most
significant event of the 19th century will be
judged as Maxwell's discovery of the laws of
electrodynamics. The American Civil War will pale
into provincial insignificance in comparison with
this important scientific event of the same
-- Richard P. Feynman The Feynman Lectures on
Physics Vol. II, page 1-11
What do Maxwells Eqs. Predict?
Corresponds to Coulombs Law
e electrical permittivity
What do Maxwells Eqs. Predict?
B magnetic flux density (magnetic
m magnetic permeability
Magnetic field lines must be closed loops
Force on moving charge q Lorentz force
What do Maxwells Eqs. Predict?
Corresponds to Faradays law of electromagnetic
A changing magnetic flux B density induces a curl
of E
The rate of change of magnetic flux through an
area A induces an electromotive force (voltage)
equal to the line integral of E around the area A.
Motors and generators are based on this principle
What do Maxwells Eqs. Predict?
permeability of free space
permittivity of free space
Extra term added by Maxwell
corresponds to Amperes Law
What do Maxwells Eqs. Predict?
In free space (J 0)
These two equations can be combined to form the
wave equation
Solutions to this equation are waves that
propagate with a velocity c given by
(the speed of light!)
James Clerk Maxwell (1831 1879)
By the time that Maxwell died in 1879 at the age
of 48 most scientists were not convinced of his
prediction of electromagnetic waves. They had
never been observed. No one knew how to generate
them or to detect them.
They would be discovered by Heinrich Hertz in
1887 and this would eventually lead to radio,
television, and cell phones….
Predicted that light was a form of
electromagnetic waves
Heinrich Hertz (1857 1894)
Generates and detects electromagnetic waves in
The frequency of electrical signals is measured
in hertz (cycles/second)
Ref http//www.sparkmuseum.com/HERTZ.HTM
Sir Joseph John Thomson (1856 1940)
Discovers the electron in 1898
Cathode Tube
J. J. Thomson
Electric Field -- corpuscle
Cavendish Labs
Albert Einstein (1879 1955)
In 1905 publishes his Special Theory of
Relativity based on two postulates
1. Absolute uniform motion cannot be detected
by any means. 2. Light is propagated in empty
space with a velocity c which is independent of
the motion of the source.
This theory predicts seemingly unusual effects
such as the measured length of moving bodies and
time intervals being dependent on the frame of
reference being used for the measurement.
Opening paragraph of On the Electrodynamics of
Moving Bodies, by Albert Einstein, Annalen der
Physik 17 (1905), p. 891.
It is well known that if we attempt to
apply Maxwell's electro-dynamics, as conceived at
the present time, to moving bodies, we are led to
asymmetry which does not agree with observed
phenomena. Let us think of the mutual action
between a magnet and a conductor. The observed
phenomena in this case depend only on the
relative motion of the conductor and the magnet,
while according to the usual conception, a
distinction must be made between the cases where
the one or the other of the bodies is in motion.
If, for example, the magnet moves and the
conductor is at rest, then an electric field of
certain energy value is produced in the
neighborhood of the magnet, which excites a
current in those parts of the field where a
conductor exists. But if the magnet be at rest
and the conductor be set in motion, no electric
field is produced in the neighborhood of the
magnet, but an electromotive force which
corresponds to no energy in itself is produced in
the conductor this causes an electric current of
the same magnitude and in the same direction as
the electric force, it being of course assumed
that the relative motion in both of these cases
is the same.
Some Electrical Inventors
  • Samuel F. B. Morse (Telegraph)
  • Guglielmo Marconi (Wireless telegraph)
  • Thomas Edison (Electric lights …..)
  • Nikola Tesla (A.C. generators, motors)
  • John Bardeen and Walter Brattain
  • Transistor
  • Jack Kilby and Robert Noyce
  • Integrated Circuit

The Telegraph
Samuel F. B. Morse (1791 1872)
Wireless Telegraph
Guglielmo Marconi
Marconi Spark Transmitter Built at the Hall
Street Chelmsford Factory September, 1897
Electric Lights
Thomas Edison 1847 - 1931
Replica of original lightbulb Patent 223,898
Invented and developed complete DC electric
generation and distribution system for city
lighting systems
Carried on a major competition with George
Westinghouse who developed an AC generation and
distribution system
Alternating Current (AC) Systems
Nikola Tesla 1856 - 1943
Over 700 patents Rotating magnetic field
principle Polyphase alternating-current system
Inducton motor AC power transmission
Telephone repeater Tesla coil transfromer
Radio Fluorescent lights
The First Point-Contact Transistor 1947
Bell Labs Museum
Bell Labs
The First Junction Transistor 1951
Texas Instruments First IC -- 1958
Jack Kilby
Robert Noyce Fairchild Intel
Moores Law
Moores Law
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