Ever wonder who invented the battery? Or how electrons, amps, volts, and ohms got their names? Curious to know who discovered that electricity and magnetism are related, and who came up with the idea for the electric motor? Has it ever occurred to you that the laws that govern voltage, current, and energy dissipation in a circuit didn’t just appear on two tablets, but were discovered after painstaking research and experimentation?
Eighteenth- and nineteenth-century scientists throughout Europe and America spent many an hour probing the mysteries of electricity and magnetism, learning from their predecessors and contemporaries, and performing experiment after experiment. The following ten individuals are among the many who contributed to the birth of the field of electronics.
Charles-Augustin de Coulomb (1736–1806) was a French physicist who is best known for characterizing the electrostatic force (that is, attraction and repulsion) between electrically charged particles. Published in 1785, Coulomb’s Law laid the foundation for the field of electromagnetism. The SI (International System of Units) unit of electrical charge is named the coulomb in honor of his discovery.
Alessandro Volta (1745–1827) was an Italian physicist and chemist whose invention of the voltaic pile (known today as a battery) in 1799 dispelled the popularly held notion that electricity could come only from living things. Volta’s invention enabled scientists to produce electric current at will, sparking further experimentation in what would become the field of electrochemistry. Volta also dabbled in electrostatics, discovering that the electric potential (that is, voltage) across a pair of capacitor plates is directly proportional to the amount of charge on the plates — a relationship known as Volta’s Law of Capacitance. The SI unit measure of electric potential — the volt — is named for Volta in recognition of his pioneering achievements.
Hans Christian Ørsted (1777–1851) was a Danish physicist and chemist who, in 1820, figured out that steady electric currents create magnetic fields. This phenomenon, known as Ørsted’s Law, was significant because at the time electricity and magnetism were believed to be separate forces. Further experimentation by Ørsted and other scientists led to the development of the field of electromagnetism.
André-Marie Ampère (1775–1836) was a French physicist and mathematician who is known as the father of electrodynamics (now known as electromagnetism). Following up on the work of Hans Christian Ørsted, Ampère developed both physical and mathematical theories to explain the interactions between electricity and magnetism, publishing his theories in 1827. Well before electrons were discovered and named in the late nineteenth century, Ampere postulated the existence of an “electrodynamic molecule.” The SI unit of current, the ampere (or amp), is named after this scientist.
Joseph Henry (1797–1878) was an American scientist and inventor who discovered the principle of self-induction and improved the design of electromagnets. Henry’s work in the 1820s and 1830s contributed to the development of electric relays, the telegraph, the DC motor, and the electric doorbell. The SI unit of inductance — the henry — is named for him.
Michael Faraday (1791–1867) was an English physicist who is best known for discovering electromagnetic induction — that is, inducing a current in a wire that is exposed to a time-varying magnetic field — in the 1830s and for his invention of electromagnetic rotary devices (such as the electric motor), which led to the practical use of electricity in technology. The SI unit of capacitance — the farad — is named for Faraday.
Georg Simon Ohm (1789–1854) was a German physicist and mathematician who discovered the proportional relationship between the voltage applied across a conductor and the strength of the current flowing through the conductor. (Georg Ohm is shown in the next figure.) Ohm published his findings, known today as Ohm’s Law, in 1827. (Another scientist, Henry Cavendish, discovered the same relationship many years before Ohm, but his experiments went unpublished until well after his death in 1810. Had Cavendish published during his lifetime, Cavendish’s Law might be used instead of Ohm’s Law and the SI unit of resistance might be a cavendish instead of an ohm.)
James Prescott Joule (1818–1889) was a self-taught British physicist (and brewer) whose discovery in the 1840s of the relationship between heat and mechanical energy led to the law of conservation of energy. Joule also discovered a relationship between the heat dissipated by a resistor and the current flowing through the resistor. The SI unit of energy bears his name.
Gustav Robert Kirchhoff (1824–1887) was a German physicist whose contributions to circuit theory have earned him the honor of having two laws named after him. First described in 1845, Kirchhoff’s Current Law (KCL) and Kirchhoff’s Voltage Law (KVL) tell us about the relationships between voltages and currents in DC circuits.
George Johnstone Stoney (1826–1911) was an Irish physicist who postulated the existence of an “atom of electricity” in 1874 and coined the term electron in the 1890s to refer to the fundamental unit of electricity. (His name might have been the most memorable on this list had he chosen to name the atom of electricity after himself!)
