Students

Formulae

Below are downloadable PDF versions of the formulae pages from the book. You can print them off or use them online to help your studies.

Download All (ZIP 1.6MB)

Famous people: biographies

André-Marie Ampère 1775 – 1836

1. Who was AMPERE? (mentioned in Chapters 1, 2 and 3)

André-Marie Ampère (1775–1836) is generally regarded as one of the founders of classical electromagnetism. The SI unit of measurement of electric c Pierre urrent, the ampere, is named after him.

Ampère developed a mathematical and physical theory to understand the relationship between electricity and magnetism, discovering that two parallel wires carrying electric currents attract or repel each other, depending on whether the currents flow in the same or opposite directions. This discovery laid the foundation to what later became known as electrodynamics. The most important of his results came to be called Ampère’s law, which states that the mutual action of two lengths of current-carrying wire is proportional to their lengths and to the intensities of their currents.

Ampère also theorized upon the existence of an ‘electrodynamic molecule’ that served as the component element of both electricity and magnetism. This was later discovered and is known today as the electron.

Mentioned in chapters 1, 2 and 3

Alexander Graham Bell 3 March 1847 – 2 August 1922

2. Who was BELL? (mentioned in Chapters 10 and 41)

Alexander Graham Bell (3 March 1847 – 2 August 1922) is credited with inventing the first practical telephone.

Bell's many years of research into hearing and speech led him to experiment with hearing devices which eventually culminated in Bell being awarded the first US patent for the telephone in 1876.

Bell is also credited with the invention of the metal detector, putting the device together in an attempt to find the bullet in the body of US President James Garfield. In 1888 he was one of the founding members of the National Geographic Society and became its second president.

Mentioned in chapters 10 and 41

Charles-Augustin de Coulomb 14 June 1736 – 23 August 1806

3. Who was COULOMB? (mentioned in Chapters 1, 2 and 6)

Charles-Augustin de Coulomb (14 June 1736 – 23 August 1806) was best known for developing Coulomb's law, the definition of the electrostatic force of attraction and repulsion.

He discovered an inverse relationship of the force betweenelectric charges and the square of its distance, later named after him as Coulomb's law. Coulomb also stated that the attractive force between two oppositely charged spheres is proportional to the quantities of charge on the spheres and is inversely proportional to the square of the distance between the spheres. The SI unit of electric charge, the coulomb, was named after Coulomb.

Mentioned in chapters 1, 2 and 6

Thomas Alva Edison 11 February 1847 – 18 October 1931

4. Who was EDISON? (mentioned in Chapter 4)

Thomas Alva Edison (11 February 1847 – 18 October 1931) was an American inventor and businessman.

Edison is the fourth most prolific inventor in history, holding well over 1,000 US patents in his name, as well as many patents elsewhere. He also developed a system of electric-power generation and distribution – a crucial development in the industrialised world. 

Edison began his career as an inventor in Newark, New Jersey, with the automatic repeater and his other improved telegraphic devices, but is remembered most for inventing the phonograph in 1877.

Edison created the first industrial research lab in Menlo Park, New Jersey. It was built with the funds from the sale of the quadruplex telegraph, his first big financial success, and became the first institution set up with the specific purpose of achieving technological innovation. In just over a decade it expanded to occupy two city blocks.

He did not invent the first electric light bulb, but instead invented the first commercially practical incandescent light. These early bulbs had an extremely short lifespan, cost a lot to produce and run, making them difficult to apply on a large scale commercially. The first successful test was on October 22, 1879, in which it lasted 13.5 hours, but he later improved this with a filament that could last over 1,200 hours.

The key to Edison's fortunes was telegraphy though. He patented the sound recording and reproducing phonograph in 1878, and was also granted a patent for the motion picture camera or ‘Kinetograph".

Thomas Edison died of complications relating to diabetes on October 18, 1931, in his home in New Jersey.

Mentioned in chapter 4

Michael Faraday 22 September 1791 – 25 August 1867

5. Who was FARADAY? (mentioned in Chapters 6, 7 & 9)

Michael Faraday, FRS (22 September 1791 – 25 August 1867) was an English scientist whose main discoveries include electromagnetic induction, diamagnetism and electrolysis

Faraday discovered two new compounds of chlorine and carbon, and also conducted the first rough experiments on the diffusion of gases. He invented an early form of what was to become the Bunsen burner, discovered chemical substances such as benzene and established that gases are the vapours of liquids possessing a very low boiling point. Faraday is also known for discovering the laws of electrolysis, and for terminology such as anode, cathode, electrode, and ion.

He established the basis for the concept of the electromagnetic field in physics, and also established that magnetism could affect rays of light and that there was an underlying relationship between the two phenomena. He discovered the principle of electromagnetic induction, diamagnetism, and the laws of electrolysis. His inventions of electromagnetic devices formed the foundation of electric motor technology, and it was largely due to his efforts that electricity became used in technology.

The SI unit of capacitance, the farad, is named in his honour.

Mentioned in chapters 6, 7 and 9

John Ambrose Fleming 29 November 1849 – 18 April 1945

6. Who was FLEMING? (mentioned in Chapters 8 and 9)

Sir John Ambrose Fleming FRS (29 November 1849 – 18 April 1945) was the English electrical engineer and physicist best known for inventing the vacuum tube.

Fleming was born in Lancaster and became a Fellow of St John's, Cambridge, in 1883. He went on to Lecture at several universities and was also a consultant to the Marconi Wireless Telegraph Company, Swan Company, Edison Telephone, and later the Edison Electric Light Company. In 1899 he became Scientific Adviser to the Marconi Company and soon after began work on designing the power plant to enable the Marconi Company to transmit across the Atlantic.

In 1904 he invented the two-electrode vacuum-tube rectifier for which he is best known. This invention is often considered to have been the beginning of electronics, and Fleming's diode was used in radio receivers and radars for many decades afterwards, until it was eventually superseded by solid state electronic technology more than 50 years later. Valves remained dominant until the arrival of the transistor in the early 1970’s.

Mentioned in chapters 8 and 9

William Gilbert 24 May 1544 – 30 November 1603

7. Who was GILBERT? (mentioned in Chapter 7)

William Gilbert, (24 May 1544 – 30 November 1603) was an English physician, physicist and natural philosopher who is credited as one of the originators of the term electricity. A unit of magnetomotive force was named the gilbert in his honour.

Gilbert concluded that the Earth was itself magnetic and that this was the reason compasses point north, and was also the first person to state that the centre of the Earth was iron. Twenty years before Galileo he pointed out the motion of the skies was due to earth's rotation. He also made the first attempt to map the surface markings on the Moon in the 1590s. Gilbert died on 30 November 1603; the cause of death is thought to have been the bubonic plague.

Mentioned in chapter 7

Joseph Henry 17 December 1797 – 13 May 1878

8. Who was HENRY? (mentioned in Chapters 9, 40 and 43)

Joseph Henry (17 December 1797 – 13 May 1878) was an American scientist who discovered the electromagnetic phenomenon of self-inductance. He also discovered mutual inductance independently of Michael Faraday, although Faraday was the first to publish his results. The SI unit of inductance, the henry, is named in his honour.

Mentioned in chapters 9, 40 and 43

James Prescott Joule 24 December 1818 – 11 October 1889

9. Who was JOULE? (mentioned in Chapters 1 and 2)

James Prescott Joule FRS (24 December 1818 – 11 October 1889) was an English physicist and brewer. He studied the nature of heat, and discovered its relationship to mechanical work. This led to the theory of conservation of energy, which in turn led to the development of the first law of thermodynamics. The SI derived unit of energy, the joule, is named after him.

Mentioned in chapters 1 and 2

Georges Leclanché 1839 – September 14, 1882

10. Who was LECLANCHE? (mentioned in Chapter 4)

Georges Leclanché (1839 – September 14, 1882) was the French electrical engineer who invented the Leclanché cell, the forerunner of the modern battery. The Leclanché cell comprised of a conducting solution of ammonium chloride with a negative terminal of zinc and a positive terminal of manganese dioxide.

Mentioned in chapter 4

Heinrich Lenz 12 February 1804 – 10 February 1865

11. Who was LENZ? (mentioned in Chapter 9)

Heinrich Friedrich Emil Lenz (12 February 1804 – 10 February 1865) was the Russian physicist remembered for formulating Lenz's law in electrodynamics. The symbol L, conventionally representing inductance, is chosen in his honour.

Mentioned in chapter 9

Gustav Robert Kirchhoff 12 March 1824 – 17 October 1887

12. Who was KIRCHHOFF? (mentioned in Chapters 13, 30 and 45)

Gustav Robert Kirchhoff (12 March 1824 – 17 October 1887) was a German physicist. Concepts in circuit theory and thermal emission are named ‘Kirchhoff's laws’ after him, as well as a law of thermochemistry.

Kirchhoff formulated his circuit laws in 1845, while still a student. In 1857 he calculated that an electric signal in a resistanceless wire travels along the wire at the speed of light. He proposed his law of thermal radiation in 1859, and gave a proof in 1861.

Mentioned in chapters 13, 30 and 45

James Maxwell 13 June 1831 – 5 November 1879

13. Who was MAXWELL? (mentioned in Chapter 7 and 27)

James Clerk Maxwell FRS FRSE (13 June 1831 – 5 November 1879) was a Scottish theoretical physicist who formulated classical electromagnetic theory. His equations demonstrate that electricity, magnetism and light are all manifestations of the same thing – the electromagnetic field.

Maxwell demonstrated that electric and magnetic fields travel through space in wave form and at the constant speed of light. He also helped to develop the Maxwell–Boltzmann distribution, a means of describing aspects of the kinetic theory of gases and presented the first durable colour photograph in 1861.

Mentioned in chapters 7 and 27

Sir Isaac Newton 25 December 1642 – 20 March 1727

14. Who was NEWTON?  (mentioned in chapter 1)

 Sir Isaac Newton (25 December 1642 – 20 March 1727) was the English polymath who laid the foundations for much of classical mechanics used today. He showed that the motions of objects are governed by the same set of natural laws by demonstrating the consistency between Kepler's laws of planetary motion and his own theory of gravitation.

Newton developed a theory of colour based on the observation that a prism decomposes white light into the many colours that form the visible spectrum. He also formulated an empirical law of cooling and studied the speed of sound. In mathematics, Newton shares the credit with Leibniz for the development of differential and integral calculus.

Newton was appointed Lucasian Professor of Mathematics in 1669. From 1670 to 1672, Newton lectured on optics. During this period he investigated refraction, demonstrating that a prism could decompose white light into a spectrum of colours, and that a lens and a second prism could recompose the multicoloured spectrum into white light. He also showed that the coloured light does not change its properties by separating out a coloured beam and shining it on various objects. Newton observed that colour is the result of objects interacting with already-coloured light rather than objects generating the colour themselves. This is known as Newton's theory of colour.

From this work, he concluded that the lens of any refracting telescope would suffer from the dispersion of light into colours (chromatic aberration). As a proof of this he constructed the first known functional reflecting telescope, today known as a Newtonian telescope, which involved solving the problems of suitable mirror material and shaping.

The Principia was published on 5 July 1687. In this work, Newton stated the three universal laws of motion.

Newton’s three laws of motion (stated in modernised form): Newton's First Law (also known as the Law of Inertia) states that an object at rest tends to stay at rest and that an object in uniform motion tends to stay in uniform motion unless acted upon by a net external force. Newton's Second Law states that an applied force on an object equals the rate of change of its momentum with time. The SI unit of force is the newton, named in Newton's honour.

Newton's Third Law states that for every action there is an equal and opposite reaction. This means that any force exerted onto an object has a counterpart force that is exerted in the opposite direction back onto the first object.

Mentioned in chapter 1

Edward Lawry Norton 28 July 1898 – 28 January 1983

15. Who was NORTON? (mentioned in Chapters 13 and 33)

Edward Lawry Norton (28 July 1898 – 28 January 1983) is best remembered for development of the dual of Thevenin's equivalent circuit, now referred to as Norton's equivalent circuit. He began his career with the Electric Company's Engineering Department, which later became Bell Laboratories. Norton’s research included network theory, acoustics, apparatus, and data transmission.

Mentioned in chapters 13 and 33

Hans Christian Oersted 14 August 1777 ‐ 9 March 1851

16. Who was OERSTED? (mentioned in Chapter 7)

 Hans Christian Ørsted (14 August 1777 - 9 March 1851) was the Danish physicist and chemist who discovered that electric currents create magnetic fields. The oersted (Oe) is named after him.

On 21 April 1820, during a lecture, he noticed that a compass needle deflected from magnetic north when an electric current from a battery was switched on and off, confirming a relationship between electricity and magnetism. His findings led to much more research into electrodynamics, influencing Ampere's development of a single mathematical formula to represent the magnetic forces between current-carrying conductors. In 1825 Ørsted produced aluminium for the first time.

Mentioned in chapter 7

Georg Simon Ohm 16 March 1789 – 6 July 1854

17. Who was OHM?  (mentioned in chapters 1 and 2)

 Georg Simon Ohm (16 March 1789 – 6 July 1854) was a Bavarian physicist and mathematician. Ohm found that there is a direct proportionality between the potential difference (voltage) applied across a conductor and the resultant electric current. This relationship is known as Ohm's law. It first appeared alongside his complete theory of electricity, in which he stated his law for electromotive force.

Mentioned in chapters 1 and 2

Pythagoras of Samos Born about 570 BC and died about 495 BC

18. Who was PYTHAGORAS?

Pythagoras of Samos (Born about 570 BC and died about 495 BC) was an Ionian Greek philosopher and mathematician.

Pythagoras made influential contributions to philosophy in the late 6th century BC. He is best known for the Pythagorean theorem, which states that in a right-angled triangle the area of the square on the hypotenuse (the side opposite the right angle) is equal to the sum of the areas of the squares of the other two sides - that is, a2 + b2 = c2

Walter H. Scottky 23 July 1886 – 4 March 1976

19. Who was SCHOTTKY?  (mentioned in chapter 11)

Walter Hermann Schottky (23 July 1886 – 4 March 1976) played a major role in developing the theory of electron and ion emission phenomena, invented the screen-grid vacuum tube and the pentode  and co-invented the Ribbon microphone and loudspeaker with Dr. Gerwin Erlach.

Schottky's most important scientific achievement was to develop the classical formula for the interaction energy between a point charge q and a flat metal surface, when the charge is at a distance x from the surface.

Mentioned in chapter 11

Nikola Tesla 10 July 1856 – 7 January 1943

20. Who was TESLA?  (mentioned in chapters 7 and 38)

Nikola Tesla (10 July 1856 – 7 January 1943) started working in the telephony and electrical fields before emigrating to the United States in 1884 to work for Thomas Edison. He soon struck out on his own though, setting up laboratories and companies to develop a range of electrical devices. In 1960, in honour of Tesla, the term ‘tesla’ was coined for the SI unit measure for magnetic field strength.

Tesla's inventions made him world-famous. In spite of making a great deal of money from his patents, Tesla ended up living as a recluse towards the end of his days and died penniless on 7 January 1943.

Mentioned in chapters 7 and 38

Léon Charles Thévenin 30 March 1857 – 21 September 1926

21. Who was THEVENIN?  (mentioned in chapters 13 and 33)

Léon Charles Thévenin (30 March 1857 – 21 September 1926) extended Ohm's law to the analysis of complex electrical circuits.

After studying Kirchhoff's circuit laws and Ohm's law, he developed Thévenin's theorem, which made it possible to calculate currents in more complex electrical circuits.

Mentioned in chapters 13 and 33

Alessandro Volta 18 February 1745 – 5 March 1827

22. Who was VOLTA?  (mentioned in chapters 1 and  2)

Alessandro Giuseppe Antonio Anastasio Volta (18 February 1745 – 5 March 1827) was the Italian physicist that invented the battery.

Volta studied the chemistry of gases, discovering methane. Volta also studied electrical capacitance, developing means to study both electrical potential (V) and charge (Q), and discovering that for a given object, they are proportional. This was named Volta's Law of capacitance, and as a result of this work the unit of electrical potential is called the volt.

Volta retired in 1819 to his estate in Camnago and died there on March 5, 1827.

Mentioned in chapters 1 and 2

James Watt 19 January 1736 – 25 August 1819

23. Who was WATT?  (mentioned in chapter 1, 2, 15 and 26)

James Watt (19 January 1736 – 25 August 1819) was a Scottish inventor and mechanical engineer.

While working at the University of Glasgow, Watt realised that the engine designs of the time wasted energy by repeatedly cooling then re-heating the cylinder. He introduced a separate condenser, which radically improved both the power and efficiency of steam engines.

The watt is named after him – the unit of power incorporated in the International System of Units (or ‘SI’).

Mentioned in chapters 1, 2, 15 and 26

Wilhelm Eduard Weber 24 October 1804 – 23 June 1891

24. Who was WEBER?  (mentioned in chapters 7 and 38)

Wilhelm Eduard Weber (24 October 1804 – 23 June 1891) was a German physicist who, together with Gauss, invented the first electromagnetic telegraph.

He studied magnetism with Gauss, and during 1864 published his Electrodynamic Proportional Measures, which contained a system of absolute measurements for electric currents and forms the basis of those in use today. The SI unit of magnetic flux, the weber (Wb) is named after him.

Mentioned in chapters 7 and 38

Charles Wheatstone 6 February 1802 – 19 October 1875

25. Who was WHEATSTONE?  (mentioned in chapter 10 and 27)

Sir Charles Wheatstone (6 February 1802 – 19 October 1875), was an English scientist and inventor of the concertina, the stereoscope, and the Playfair cipher. He is best known for his contributions in the development of the Wheatstone bridge, which is used to measure an unknown electrical resistance.

Mentioned in chapters 10 and 27

Clarence Zener 1 December 1905 – 15 July 1993

26. Who was ZENER?  (mentioned in chapter 11)

Clarence Melvin Zener (1 December 1905 – 15 July 1993) was the first person to describe the breakdown of electrical insulators. His findings were later used by Bell Labs in the development of the Zener diode.

Zener was a theoretical physicist with a background in mathematics who researched in a wide range of subject areas, including superconductivity, ferromagnetism, metallurgy, elasticity, diffusion, fracture mechanics and geometric programming.

Mentioned in chapter 11