Transcript Digital Design

A Brief History
of Electricity
Lecture L0.0
Some Electrical Pioneers
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Ancient Greeks
William Gilbert
Pieter van Musschenbroek
Benjamin Franklin
Charles Coulomb
Alessandro Volta
Hans Christian Oersted
Some Electrical Pioneers (cont.)
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Andre-Marie Ampere
Michael Faraday
Joseph Henry
James Clerk Maxwell
Heinrich Hertz
J. J. Thomson
Albert Einstein
Some Electrical Inventors
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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 Elizabeth.
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 jar.
Leyden jar (also called condenser)
Ref: http://chem.ch.huji.ac.il/~eugeniik/history/musschenbroek.htm
Leyden Jars
700 pF, 175 KV
Q=CxV
= 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
Refs:
http://www.alaska.net/~natnkell/leyden.htm
http://home.earthlink.net/~lenyr/stat-gen.htm
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.
Coulomb’s Law
F1 
1
4 0
q1q2
e12
2
4 0 r12
1
 107 c 2  9.0 109
Unit: Newton meter / coulomb2
volt meter / coulomb
Alessandro Volta (1745 – 1827)
Interpreted Galvani’s experiment
with decapitated frogs as
involving the generation of
current flowing through the
moist flesh of the frog’s 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 solution.
Hans Christian Oersted (1777 – 1851)
X
In 1820 he showed that a current
produces a magnetic field.
Ref: http://chem.ch.huji.ac.il/~eugeniik/history/oersted.htm
André-Marie Ampère (1775 – 1836)
French mathematics professor who only
a week after learning of Oersted’s
discoveries in Sept. 1820 demonstrated
that parallel wires carrying currents
attract and repel each other.
attract
A moving charge of 1 coulomb
per second is a current of
1 ampere (amp).
repel
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 Institution.
Discovered selfinduction
Built the largest
electromagnets of
his day
Unit of inductance, L, is the “Henry”
James Clerk Maxwell (1831 – 1879)
Born in Edinburgh, Scotland;
Taught at King’s College in London
(1860-1865) and was the first
Cavendish Professor of Physics at
Cambridge (1871-1879).
Provided a mathematical description of
Faraday’s lines of force.
Developed “Maxwell’s Equations” which
describe the interaction of electric and
Predicted that light was a magnetic fields.
B
E  
form of electromagnetic
 D  
t
waves
D
B  0
H  J 
D  E
B  H
t
“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 decade”.
-- Richard P. Feynman
The Feynman Lectures on Physics
Vol. II, page 1-11
What do Maxwell’s Eqs. Predict?
 D  
D  E
Corresponds to Coulomb’s Law
  electrical permittivity
E
F  qE
Area of sphere  4 r 2
What do Maxwell’s Eqs. Predict?
B  0
B = magnetic flux density
(magnetic induction)
B  H
  magnetic permeability
Magnetic field lines
must be closed loops
Force on moving charge q
Lorentz force
F  q ( v  B)
B
What do Maxwell’s Eqs. Predict?
E  
B
t
Corresponds to Faraday’s law of
electromagnetic induction
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 Maxwell’s Eqs. Predict?
D
H  J 
t
B  0 H
0  permeability of free space
D   0E
 0  permittivity of free space
E
  B   0 J   0 0
t
Extra term added
by Maxwell
 B  0 J corresponds to Ampere’s Law
B
J
X
What do Maxwell’s Eqs. Predict?
In free space (J = 0)
B
E  
t
E
  B  0 0
t
These two equations can be combined to form the wave equation
2

E
 2 E   0 0 2
t
Solutions to this equation are waves that propagate with
a velocity c given by
c
1
0 0
 3 108 m / sec
(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.
Predicted that light was a
form of electromagnetic
waves
They would be discovered by
Heinrich Hertz in 1887 and this
would eventually lead to radio,
television, and cell phones….
Heinrich Hertz (1857 – 1894)
Generates and detects electromagnetic waves
in 1887
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
Bell Labs Museum
The First
Point-Contact
Transistor
1947
Bell Labs
The First
Junction Transistor
1951
Texas Instrument’s First IC -- 1958
Jack Kilby
Robert Noyce
Fairchild
Intel
Moore’s Law
Moore's Law
(As predicted by Gordon E. Moore in 1965)
Transistors
10000
100
1
1959
1960
1961
1962
1963
1964
1965
1966
1967
Year
1968
1969
1970
1971
1972
1973
1974
1975
Moore’s Law
10000
Moore's Law
(Doubling every 2 years)
1000
Transistors (in millions)
100
16M
Pentium 4
4M
10
Pentium II
1M
486
Pentium
1
64K
Memory
286
Microprocessor
0.1
8080
0.01
0.001
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Year