Heinrich Rudolf Hertz (February 22, 1857 – January 1, 1894) was a German physicist who clarified and expanded the electromagnetic theory of light that had been put forth by Maxwell James Clerk Maxwell was a Scottish theoretical physicist and mathematician. His most important achievement was classical electromagnetic theory, synthesizing all previously unrelated observations, experiments and equations of electricity, magnetism and even optics into a consistent theory. His set of equations—Maxwell's equations—demonstrated. He was the first to satisfactorily demonstrate the existence of electromagnetic waves Electromagnetic radiation is a phenomenon that takes the form of self-propagating waves in a vacuum or in matter. It consists of electric and magnetic field components which oscillate in phase perpendicular to each other and perpendicular to the direction of energy propagation. Electromagnetic radiation is classified into several types according by building an apparatus to produce and detect VHF Common uses for VHF are FM radio broadcast, television broadcast, land mobile stations , long range data communication with radio modems, Amateur Radio, marine communications, air traffic control communications and air navigation systems (e.g. VOR, DME & ILS) or UHF Ultra high frequency designates a range of electromagnetic waves with frequencies between 300 MHz and 3 GHz (3,000 MHz), also known as the decimetre band or decimetre wave as the wavelengths range from one to ten decimetres (10 cm to 1 metre). Radio waves with frequencies above the UHF band fall into the SHF (super high frequency) and EHF ( radio Radio is the transmission of signals by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space. Information is carried by systematically changing some property of the radiated waves, such as waves.

Biography

Early years

Hertz was born in Hamburg Hamburg is the second-largest city in Germany (second to Berlin) and the eighth-largest city in the European Union. The city is home to over 1.8 million people, while the Hamburg Metropolitan Region (including parts of the neighboring Federal States of Lower Saxony and Schleswig-Holstein) has more than 4.3 million inhabitants. The port of Hamburg, Germany The German Confederation or Germanic Confederation was the association of Central European states created by the Congress of Vienna in 1815 to serve as the successor to the Holy Roman Empire of the German Nation, which had been abolished in 1806. In 1848, revolutions by liberals and nationalists occurred in an attempt to establish a unified German, into a prosperous and cultured Hanseatic family. His father, Gustav Ferdinand Hertz, was a barrister and later a senator. His mother was the former Anna Elisabeth Pfefferkorn. He had three younger brothers and one younger sister.^[1]

While studying at the Gelehrtenschule des Johanneums of Hamburg, he showed an aptitude for sciences as well as languages, learning Arabic Arabic (العربية al-ʿarabīyah, ( Arabic pronunciation ) or عربي ʿarabi) is a Central Semitic language, thus related to and classified alongside other Semitic languages such as Hebrew and the Neo-Aramaic languages. Arabic has more speakers than any other language in the Semitic language family. It is spoken by more than 280 million and Sanskrit Sanskrit , is a historical Indo-Aryan language and the primary liturgical language of Hinduism and Buddhism[note 1]. Today, it is listed as one of the 22 scheduled languages of India and is an official language of the state of Uttarakhand. He studied sciences and engineering in the German cities of Dresden Dresden is the capital city of the Free State of Saxony in Germany. It is situated in a valley on the River Elbe, near the Czech border. The Dresden conurbation is part of the Saxon Triangle metropolitan area, Munich The Technische Universität München is a research university with campuses in Munich, Garching, and Weihenstephan and Berlin The Humboldt University of Berlin is Berlin's oldest university, founded in 1810 as the University of Berlin (Universität zu Berlin) by the liberal Prussian educational reformer and linguist Wilhelm von Humboldt, whose university model has strongly influenced other European and Western universities. From 1828 it was known as the Frederick William, where he studied under Gustav R. Kirchhoff and Hermann von Helmholtz Hermann Ludwig Ferdinand von Helmholtz was a German physician and physicist who made significant contributions to several widely varied areas of modern science. In physiology and psychology, he is known for his mathematics of the eye, theories of vision, ideas on the visual perception of space, color vision research, and on the sensation of tone,.

In 1880, Hertz obtained his PhD Doctor of Philosophy, abbreviated to PhD, Ph.D. or D.Phil. in English-speaking countries and Dr. Phil. or similar in other countries, for the Latin philosophiae doctor, meaning "teacher in philosophy", is an advanced academic degree awarded by universities. In most English-speaking countries, the PhD is the highest degree one can earn from the University of Berlin The Humboldt University of Berlin is Berlin's oldest university, founded in 1810 as the University of Berlin (Universität zu Berlin) by the liberal Prussian educational reformer and linguist Wilhelm von Humboldt, whose university model has strongly influenced other European and Western universities. From 1828 it was known as the Frederick William; and remained for post-doctoral study under Helmholtz.

In 1883, Hertz took a post as a lecturer in theoretical physics at the University of Kiel.

In 1885, Hertz became a full professor at the University of Karlsruhe The Karlsruhe Institute of Technology is an academic research and education institution resulting from a merger of the university (Universität Karlsruhe (TH)) and the research center (Forschungszentrum Karlsruhe). It is located in the city of Karlsruhe, Germany. The university was also known as Fridericiana and was founded in 1825. It recently where he discovered electromagnetic waves.

Meteorology

Hertz always had a deep interest in meteorology Meteorology is the interdisciplinary scientific study of the atmosphere that focuses on weather processes and short term forecasting . Studies in the field stretch back millennia, though significant progress in meteorology did not occur until the eighteenth century. The nineteenth century saw breakthroughs occur after observing networks developed probably derived from his contacts with Wilhelm von Bezold (who was Hertz's professor in a laboratory course at the Munich Polytechnic The Technische Universität München is a research university with campuses in Munich, Garching, and Weihenstephan in the summer of 1878). Hertz, however, did not contribute much to the field himself except some early articles as an assistant to Helmholtz in Berlin Berlin (English pronunciation: /bɜrˈlɪn/; German pronunciation: [bɛɐ̯ˈliːn] ) is the capital city and one of 16 states of Germany. With a population of 3.4 million people, Berlin is Germany's largest city. It is the second most populous city proper and the eighth most populous urban area in the European Union. Located in northeastern, including research on the evaporation Evaporation is a type of vaporization of a liquid, that occurs only on the surface of a liquid. The other type of vaporization is boiling, that instead occurs on the entire mass of the liquid. Evaporation is also part of the water cycle of liquids Liquid is one of the three classical states of matter. Like a gas, a liquid is able to flow and take the shape of a container, but, like a solid, it resists compression. Unlike a gas, a liquid does not disperse to fill every space of a container, and maintains a fairly constant density. A distinctive property of the liquid state is surface tension,, a new kind of hygrometer Hygrometers are instruments used for measuring relative humidity. A simple form of a hygrometer is specifically known as a psychrometer and consists of two thermometers, one of which includes a dry bulb and one of which includes a bulb that is kept wet to measure wet-bulb temperature. Modern electronic devices use temperature of condensation,, and a graphical means of determining the properties of moist air when subjected to adiabatic Adiabatic heating or cooling of a gas results from pressure change. Work is done on or by the gas, but there is no heat transfer with the environment. Heat can be supplied to the gas by friction however. If an adiabatic process is frictionless too, the process is reversible and can be called isentropic changes.^[2]

Contact mechanics

In 1881–1882, Hertz published two articles on what was to become known as the field of contact mechanics. Hertz is well known for his contributions to the field of electrodynamics (see below); however, most papers that look into the fundamental nature of contact cite his two papers as a source for some important ideas. Joseph Valentin Boussinesq published some critically important observations on Hertz's work, nevertheless establishing this work on contact mechanics to be of immense importance. His work basically summarises how two axi-symmetric objects placed in contact will behave under loading, he obtained results based upon the classical theory of elasticity and continuum mechanics. The most significant failure of his theory was the neglect of any nature of adhesion between the two solids, which proves to be important as the materials composing the solids start to assume high elasticity. It was natural to neglect adhesion in that age as there were no experimental methods of testing for it.

To develop his theory Hertz used his observation of elliptical Newton's rings The phenomenon of Newton's rings, named after Isaac Newton, is an interference pattern caused by the reflection of light between two surfaces - a spherical surface and an adjacent flat surface. When viewed with monochromatic light it appears as a series of concentric, alternating light and dark rings centered at the point of contact between the formed upon placing a glass sphere upon a lens as the basis of assuming that the pressure exerted by the sphere follows an elliptical distribution. He used the formation of Newton's rings again while validating his theory with experiments in calculating the displacement which the sphere has into the lens. K. L. Johnson, K. Kendall and A. D. Roberts (JKR) used this theory as a basis while calculating the theoretical displacement or indentation depth in the presence of adhesion in their landmark article "Surface energy and contact of elastic solids" published in 1971 in the Proceedings of the Royal Society (A324, 1558, 301-313). Hertz's theory is recovered from their formulation if the adhesion of the materials is assumed to be zero. Similar to this theory, however using different assumptions, B. V. Derjaguin, V. M. Muller and Y. P. Toporov published another theory in 1975, which came to be known as the DMT theory in the research community, which also recovered Hertz's formulations under the assumption of zero adhesion. This DMT theory proved to be rather premature and needed several revisions before it came to be accepted as another material contact theory in addition to the JKR theory. Both the DMT and the JKR theories form the basis of contact mechanics upon which all transition contact models are based and used in material parameter prediction in Nanoindentation and Atomic Force Microscopy. So Hertz's research from his days as a lecturer, preceding his great work on electromagnetism, which he himself considered with his characteristic soberness to be trivial, has come down to the age of nanotechnology.

Electromagnetic research

Hertz helped establish the photoelectric effect In the photoelectric effect, electrons are emitted from matter as a consequence of their absorption of energy from electromagnetic radiation of very short wavelength, such as visible or ultraviolet light. Electrons emitted in this manner may be referred to as "photoelectrons". First observed by Heinrich Hertz in 1887, the phenomenon is (which was later explained by Albert Einstein Albert Einstein (pronounced /ˈælbərt ˈaɪnstaɪn/; German: [ˈalbɐt ˈaɪnʃtaɪn] ; 14 March 1879 – 18 April 1955) was a theoretical physicist, philosopher and author who is widely regarded as one of the most influential and best known scientists and intellectuals of all time. A German-Swiss Nobel laureate, he is often regarded as the) when he noticed that a charged Electric charge is a fundamental conserved property of some subatomic particles, which determines their electromagnetic interaction. Electrically charged matter is influenced by, and produces, electromagnetic fields. The interaction between a moving charge and an electromagnetic field is the source of the electromagnetic force, which is one of the object loses its charge more readily when illuminated by ultraviolet light. In 1887, he made observations of the photoelectric effect and of the production and reception of electromagnetic (EM) waves, published in the journal Annalen der Physik. His receiver consisted of a coil with a spark gap A spark gap consists of an arrangement of two conducting electrodes separated by a gap usually filled with a gas such as air, designed to allow an electric spark to pass between the conductors. When the voltage difference between the conductors exceeds the gap's breakdown voltage, a spark forms, ionizing the gas and drastically reducing its, whereupon a spark would be seen upon detection of EM waves. He placed the apparatus in a darkened box to see the spark better. He observed that the maximum spark length was reduced when in the box. A glass panel placed between the source of EM waves and the receiver absorbed ultraviolet radiation that assisted the electrons in jumping across the gap.

When removed, the spark length would increase. He observed no decrease in spark length when he substituted quartz for glass, as quartz Quartz is the second most abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2 does not absorb UV radiation. Hertz concluded his months of investigation and reported the results obtained. He did not further pursue investigation of this effect, nor did he make any attempt at explaining how the observed phenomenon was brought about.

Earlier in 1886, Hertz developed the Hertz antenna receiver. This is a set of terminals that is not electrically grounded for its operation. He also developed a transmitting type of dipole antenna A dipole antenna, is a radio antenna that can be made by a simple wire, with a center-fed driven element. These antennas are the simplest practical antennas from a theoretical point of view; the current amplitude on such an antenna decreases uniformly from maximum at the center to zero at the ends. Dipole antennas were created by Heinrich Rudolph, which was a center-fed driven element for transmitting UHF Ultra high frequency designates a range of electromagnetic waves with frequencies between 300 MHz and 3 GHz (3,000 MHz), also known as the decimetre band or decimetre wave as the wavelengths range from one to ten decimetres (10 cm to 1 metre). Radio waves with frequencies above the UHF band fall into the SHF (super high frequency) and EHF ( radio waves. These antennas are the simplest practical antennas from a theoretical point of view. In 1887, Hertz experimented with radio waves in his laboratory. These actions followed Michelson's Albert Abraham Michelson was an American physicist known for his work on the measurement of the speed of light and especially for the Michelson-Morley experiment. In 1907 he received the Nobel Prize in Physics. He became the first American to receive the Nobel Prize in sciences 1881 experiment (precursor to the 1887 Michelson-Morley experiment The Michelson–Morley experiment was performed in 1887 by Albert Michelson and Edward Morley at what is now Case Western Reserve University. Its results are generally considered to be the first strong evidence against the theory of a luminiferous aether. The experiment has also been referred to as "the kicking-off point for the theoretical) which did not detect the existence of aether drift In the late 19th century, "luminiferous aether" , meaning light-bearing aether, was the term used to describe a medium for the propagation of light. The word aether stems via Latin from the Greek αιθήρ, from a root meaning to kindle, burn, or shine. It signifies the substance which was thought in ancient times to contain the, Hertz altered the Maxwell's equations Maxwell's equations are a set of four partial differential equations that relate the electric and magnetic fields to their sources, charge density and current density. These equations can be combined to show that light is an electromagnetic wave. Individually, the equations are known as Gauss's law, Gauss's law for magnetism, Faraday's law of to take this view into account for electromagnetism. Hertz used a Ruhmkorff coil An induction coil or "spark coil" is a type of disruptive discharge coil. It is a type of electrical transformer used to produce high-voltage pulses from a low-voltage DC supply. To create the flux changes necessary to induce voltage in the secondary, the DC current in the primary is repeatedly interrupted by a vibrating mechanical-driven spark gap and one meter wire pair as a radiator. Capacity spheres were present at the ends for circuit resonance adjustments. His receiver, a precursor to the dipole antenna, was a simple half-wave dipole antenna for shortwaves Shortwave radio refers to the HF portion of the radio spectrum, between 3,000–30,000 kHz. Shortwave radio received its name because the wavelengths in this band are shorter than those used for medium and low frequency bands first used for radio communications.

Through experimentation, he proved that transverse A transverse wave is a moving wave that consists of oscillations occurring perpendicular to the direction of energy transfer. If a transverse wave is moving in the positive x-direction, its oscillations are in up and down directions that lie in the y-z plane free space In classical physics, free space is a concept of electromagnetic theory, corresponding to a theoretically perfect vacuum and sometimes referred to as the vacuum of free space, or as classical vacuum, and is appropriately viewed as a reference medium electromagnetic waves Electromagnetic radiation is a phenomenon that takes the form of self-propagating waves in a vacuum or in matter. It consists of electric and magnetic field components which oscillate in phase perpendicular to each other and perpendicular to the direction of energy propagation. Electromagnetic radiation is classified into several types according can travel over some distance. This had been predicted by James Clerk Maxwell James Clerk Maxwell was a Scottish theoretical physicist and mathematician. His most important achievement was classical electromagnetic theory, synthesizing all previously unrelated observations, experiments and equations of electricity, magnetism and even optics into a consistent theory. His set of equations—Maxwell's equations—demonstrated and Michael Faraday Michael Faraday, FRS was an English chemist and physicist (or natural philosopher, in the terminology of the time) who contributed to the fields of electromagnetism and electrochemistry. With his apparatus configuration, the electric and magnetic fields would radiate away from the wires as transverse waves. Hertz had positioned the oscillator about 12 meters from a zinc Zinc , also known as spelter, is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2. Zinc is the 24th most abundant element in the reflecting plate to produce standing waves This phenomenon can occur because the medium is moving in the opposite direction to the wave, or it can arise in a stationary medium as a result of interference between two waves traveling in opposite directions. In the second case, for waves of equal amplitude traveling in opposing directions, there is on average no net propagation of energy. Each wave was about 4 meters. Using the ring detector, he recorded how the magnitude Amplitude is the magnitude of change in the oscillating variable with each oscillation within an oscillating system. For example, sound waves in air are oscillations in atmospheric pressure and their amplitudes are proportional to the change in pressure during one oscillation. If a variable undergoes regular oscillations, and a graph of the system and wave's component direction vary. Hertz measured Maxwell's waves and demonstrated that the velocity of radio waves was equal to the velocity of light. The electric field intensity and polarity Polarization is a property of certain types of waves that describes the orientation of their oscillations. Electromagnetic waves such as light exhibit polarization; acoustic waves (sound waves) in a gas or liquid do not have polarization because the direction of vibration and direction of propagation are the same was also measured by Hertz. (Hertz, 1887, 1888).

The Hertzian cone A Hertzian cone is the cone of force that propagates through a brittle, amorphous or cryptocrystalline solid material from a point of impact, eventually removing a full or partial cone. An example often occurs when a plate-glass window is struck by a small object, such as an airgun projectile. This is the physical principle that explains the form was first described by Hertz as a type of wave-front propagation through various media A transmission medium is a material substance (solid, liquid or gas) which can propagate energy waves. For example, the transmission medium for sound received by the ears is usually air, but solids and liquids may also act as transmission media for sound. His experiments expanded the field of electromagnetic transmission and his apparatus was developed further by others in the radio Radio is the transmission of signals by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space. Information is carried by systematically changing some property of the radiated waves, such as. Hertz also found that radio waves could be transmitted through different types of materials, and were reflected by others, leading in the distant future to radar Radar is an object-detection system that uses electromagnetic waves - specifically radio waves - to identify the range, altitude, direction, or speed of both moving and fixed objects such as aircraft, ships, spacecraft, mountain ranges, radio and TV towers, guided missiles, motor vehicles, weather formations, and terrain. The radar dish, or.

Hertz did not realize the practical importance of his experiments. He stated that,

"It's of no use whatsoever[...] this is just an experiment that proves Maestro Maxwell was right - we just have these mysterious electromagnetic waves that we cannot see with the naked eye. But they are there." ^[3]

Asked about the ramifications of his discoveries, Hertz replied,

"Nothing, I guess." ^[3]

His discoveries would later be more fully understood by others and be part of the new "wireless age". In bulk, Hertz' experiments explain reflection, refraction, polarization, interference, and velocity of electric waves.

In 1892, Hertz began experimenting and demonstrated that cathode rays could penetrate very thin metal foil (such as aluminium). Philipp Lenard, a student of Heinrich Hertz, further researched this "ray effect". He developed a version of the cathode tube and studied the penetration by X-rays of various materials. Philipp Lenard, though, did not realize that he was producing X-rays. Hermann von Helmholtz formulated mathematical equations for X-rays. He postulated a dispersion theory before Röntgen made his discovery and announcement. It was formed on the basis of the electromagnetic theory of light (Wiedmann's Annalen, Vol. XLVIII). However, he did not work with actual X-rays.

Death at age 36

In 1892, an infection was diagnosed (after a bout of severe migraines) and Hertz underwent some operations to correct the illness. He died of Wegener's granulomatosis at the age of 36 in Bonn, Germany in 1894, and was buried in Ohlsdorf, Hamburg at the Jewish cemetery.^[4]

Hertz's wife, Elizabeth Hertz (maiden name: Elizabeth Doll), did not remarry. Heinrich Hertz left two daughters, Joanna and Mathilde. Subsequently, all three women left Germany in the 1930s to England, after the rise of Adolf Hitler. Charles Susskind interviewed Mathilde Hertz in the 1960s and he later published a book on Heinrich Hertz. Heinrich Hertz's daughters never married and he does not have any descendants, according to the book by Susskind.

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