ECE 1304 Introduction to Electrical and

Computer Engineering

What is Electrical Engineering?

Part 1

(Antiquity to 1900)

What is Electricity?

• Electromagnetism is a property of the universe that may be used to …–Transmit and convert energy.–Transmit and manipulate information.

• Electrical Engineers use these properties to make useful things.

Thales of Miletus (624-546 BC)

Described static electricity and magnetism.

He noticed that when amber (fossilized tree resin) was rubbed with fur, it would attract other objects (like bits of straw). The classical Greek name for amber was ἤλεκτρον (ēlektron).

He also noticed that lodestone (a naturally magnetized mineral) attracted bits of iron. Lodestones may have come from Magnesia and were known as μαγνήτις λίθος (magnētis lithos, “Magnesian stone”)

William Gilbert (1544-1603)

The Father of Electrical Engineering

Wrote De Magnete (On the Magnet and Magnetic Bodies, and on the Great Magnet the Earth, 1600) in which he described the earth as a magnet. He also described static electricity and called it electric force (because he too, used amber). Invented the Electroscope to detect electric charge.

Otto von Guericke (1601-1674)

Invented an electrostatic generator. A Sulphur ball was rotated in a wooden cradle and rubbed by hand. The charged ball was then transported on the end of an insulating rod.

Alessandro Volta (1745-1827)

Italian physicist and chemist, invented the electrical battery by alternately stacking copper and zinc discs separated by brine soaked cloth creating the Voltaic Pile.

The unit of electric potential is named after him.

André-Marie Ampère (1775-1836)

Demonstrated the connection between electricity and magnetism by showing that two parallel wires carrying electrical current experienced a force.

The unit of electrical current is named after him.

Gaston Planté (1834-1889)

Invented the lead-acid battery in 1859. His was the first battery that could be recharged by passing a reverse current through it. Planté's first model consisted of two lead sheets separated by rubber strips and rolled into a spiral. His batteries were first used to power the lights in train carriages while stopped at a station.

The re-chargeable lead-acid battery is used in automobiles.

Michael Faraday (1791-1867)

Discovered electromagnetic induction. A time-varying current passing through a coil can induce a current in a second (electrically isolated coil).

Constructed the first electric generators and motors.

Inexplicably honored by his name used as the unit of Capacitance, the Farad.

Faraday’s experiment with induction.

Joseph Henry (1797-1878)

Invented a practical electromagnetic rely. This became the basis of the electrical telegraph.

The unit of Inductance is named for him.

James Clerk Maxwell (1831-1879)

Formulated the Classical Theory of Electromagnetics.

Brought together electricity and magnetism into a unifying set of equations.

Demonstrated that electric and magnetic fields propagate through space as waves.

Demonstrated that light, electricity and magnetism are manifestations of the same phenomenon.

13

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Maxwell’s Equations(Integral Form)

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14

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Maxwell’s Equations(Vector Form)

15

Maxwell’s Equations

Heinrich Hertz (1857-1894)

Proved the existence of electromagnetic waves that were theorized by Maxwell.

The unit of frequency was named in his honor.

Pavel Schilling (1786-1837)

Russian diplomat. Built the first electric telegraph.

Schilling's first electromagnetic telegraph was set up in his apartment in St Petersburg in 1832.

Samuel Morse (1791-1872)

American Painter and developer of electromagnetic telegraphy.

In 1844, Morse sent the message “WHAT HATH GOD WROUGHT” from Washington, D.C., to Baltimore, Maryland.

Developed a code that assigned a set of dots and dashes to each letter of the English alphabet and allowed for the simple transmission of complex messages across telegraph lines.

Morse Code

High-speed Communication!

Pony Express Route April 3, 1860 – October 24, 1861

Telegraph Key (1854)

Telegraphic Instruments

Alexander Graham Bell (1847-1922)

In 1875, Bell developed an acoustic telegraph that used frequency division multiplexing to transmit multiple telegraph messages on a single line.

Patent 174,465, issued on March 7, 1876 covered “the method of, and apparatus for, transmitting vocal or other sounds telegraphically ... by causing electrical undulations, similar in form to the vibrations of the air accompanying the said vocal or other sound.”

Bell placing the first New York to Chicago telephone call in 1892

Electric Automobile

Thomas Parker, 1884 London

Electric Automobile

1907 Detroit Electric