Ancient Inventions in Electronics

In 1837, the first electric motor was developed (and patented) in the USA by Thomas Davenport. A few years later, in 1839, the magnetohydrodynamic battery was proposed by Michael Faraday in the UK; the photovoltaic effect was described in France by Alexandre Edmond Becquerel (1820–91), and the fuel cell was invented by Sir William Robert Grove (1811–96) in the UK. In 1843, the Scottish inventor Alexander Bain patented what has become known as facsimile reproduction (fax), and in 1845–47 the German physicist Gustav Robert Kirchoff (1824–87) published the two famous laws that are named after him. In 1847, George Boole (1815–64) published his first ideas on symbolic logic, although his major work, Investigation of the Laws of Thought was not published until 1854. The kind of symbolic algebra that Boole developed led to Boolean algebras, which are, of course, of great significance in modern algebra and computing. In 1852, thin film technology was introduced by Sir William Robert Grove. In 1860, professor T J Wray gave a public demonstration of the mercury arc lamp on the Hungerford Bridge in London, and in Germany, the physicist Johann Philipp Reis (1834–74) developed the first microphone. Unfortunately, this microphone was considered a toy and quickly forgotten. Another important contribution to electrical technology came from the French physicist Robert Louis Gaston Planté (1834–89), who in 1859 developed the lead-acid cell, which was the world’s first practical rechargeable or secondary battery. In fact, the lead-acid battery is even today the most widely used rechargeable battery in the world. In the same year, Michael Faraday discovered that silver sulphide possesses a high negative temperature coefficient. This discovery forms the basis of what are now termed thermistors, that is, temperature-sensitive non-linear resistors. The name thermistor was coined by the Bell Telephone Laboratories of the USA during their research into materials for these components. Also in that year, one of the century’s foremost experimentalists, the English physicist James Prescott Joule (1818–89) described magnetostriction, a phenomenon in which the mechanical dimension of a magnetic material is altered as the magnetization is varied. Perhaps the most able theoretician of the 19th century, the Scottish physicist James Clerk Maxwell (1831–79), started his monumental research on electromagnetism in the late 1850s. This laid the foundations for the work of the German physicist Heinrich Rudolph Hertz (1857–94) in discovering radio waves. Maxwell’s ‘equations’ (1864) form fundamental laws of theoretical physics that govern the behaviour of electromagnetic (radio; television) waves in all practical situations. The equations are used to analyse the propagation of radio waves in free space, at all sorts of boundary, and in all guided-wave structures or transmission lines. His field equations are mathematical formulations of the laws of Gauss, Faraday and Ampère from which the theory of electromagnetic waves can be derived. The Maxwell bridge can be used for the measurement of capacitance and inductance. Maxwell’s Rule states that every part of an electric circuit is acted upon by a force tending to move in such a direction as to enclose the maximum magnetic flux.

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