A Brief History of Electricity

Discussion D1.0

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 • Marcian (Ted) Hoff (microprocessor)

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

Q = C x V = 700 x 10 -12 = 1.225 x 10 -4 x 175 x 10 3 coulombs 700 pF, 175 KV No. of electrons = 1.225 x 10 -4 coulombs / 1.6 x 10 -19 coul/elec = 7.66 x 10 14 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

F

1  1 4  0

q q

1 2

r

12 2

e

12 1 4  0  10  7

c

2   9 Unit: Newton meter 2 / coulomb 2 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.

The energy in

joules

required to move a charge of one

coulomb

through an element is 1

volt

.

Hans Christian Oersted (1777 – 1851)

X 1822 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 (1791 – 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) Faraday’s electromagnetic induction ring

Joseph Henry (1797 – 1878)

American scientist, Princeton University professor, and first Secretary of the Smithsonian Institution.

Discovered self induction 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.

Predicted that light was a form of electromagnetic waves

D

 

E B

 

H

Developed “Maxwell’s Equations” which describe the interaction of electric and magnetic fields.

 0 

B



t



D



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

 

E

 Corresponds to Coulomb’s Law   electrical permittivity

E F



q

E

Area of sphere

 4 

r

2

What do Maxwell’s Eqs. Predict?

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

 

B

)

B

What do Maxwell’s Eqs. Predict?



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



t

B

  0

H D

  0

E

 0  permeability of free space  0  permittivity of free space  0

J

   0 0  0

J



E



t

Extra term added by Maxwell corresponds to Ampere’s Law

B J

X

What do Maxwell’s Eqs. Predict?

In free space (

J

= 0) 

B



t

  0 0 

E



t

These two equations can be combined to form the wave equation  2

E

   0 0  2

E



t

2 Solutions to this equation are waves that propagate with a velocity

c

given by

c

 1   0 0   8 (the speed of light!)

James Clerk Maxwell (1831 – 1879)

Predicted that light was a form of electromagnetic waves 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….

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

Thomas Edison 1847 - 1931

Electric Lights

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 Lab model M1752 Outside the Lab

Texas Instrument’s First IC -- 1958 Jack Kilby Robert Noyce Fairchild Intel

Moore’s Law

10000 1000

Moore's Law (Doubling every 2 years)

100 10 1 64K 286 1M 4M 486 16M Pentium Pentium 4 Pentium II Memory Microprocessor 0.1

8080 0.01

0.001

1974 1976 1978 1980 1982 1984 1986 1988 1990 1992

Year

1994 1996 1998 2000 2002 2004 2006 2008 2010

Moore’s law

• Wow – This growth rate is hard to imagine, most people underestimate – How many ancestors do you have from 20 generations ago • i.e., roughly how many people alive in the 1500’s did it take to make you?

• 2 20 = more than

1 million people

Moore's Law leads to need for Electronic Design Automation (EDA)

10000 1000 100 10 1 0.1

8080 0.01

Moore's Law (Doubling every 2 years)

64K 286 1M 4M 486 16M Pentium Pentium 4 Pentium II Memory Microprocessor 0.001

1974 1976 1978 1980 1982 1984 1986 1988 1990 1992

Year

1994 1996 1998 2000 2002 2004 2006 2008 2010

Electronic Design Automation (EDA)

• PSpice – analyze analog circuits –

SPICE

(Simulation Program with Integrated Circuits Emphasis) – 1970s: SPICE – Nagel and Pederson – 1980s: PSpice – Microsim Corp.

– 1998: Merged with OrCAD

Electronic Design Automation (EDA)

• Verilog – Digital Design – 1984: Gateway Design Automation Inc. – 1990: acquired by Cadence Design System – 1995: Verilog becomes an IEEE Standard • VHDL – Digital Design – V: VHSIC (Very High Speed Integrated Circuit) – HDL: Hardware Description Language – Developed under government contract in the 1980s – 1987 (1993) IEEE standard (IEEE 1076)