106 Sentences With "cathode rays" | Random Sentence Generator

On the job, one dad crushed cathode rays without being given protective equipment to wear.

Becquerel himself, in 1900, showed that beta particles were the same as Thomson's cathode rays.

When the electrode was heated, it would shoot cathode rays across the chamber toward the sphere.

On the other side of the cathode rays, viewers at home relate to the anchor as if, yes, that person is talking to them.

The following year, J.J. Thomson worked out that "cathode rays" emitted into a vacuum by a negative electrode were electrically charged particles that weighed far less than any atom.

In January 1896, Röntgen presented his "X-ray," so named for its then-unknown properties that he'd found while experimenting with cathode rays, to the Würzburg Physico-Medical Society.

The wave-like behaviour of cathode rays was later directly demonstrated using a crystal lattice by Davisson and Germer in 1927.

The cathode ray tube by which J. J. Thomson demonstrated that cathode rays could be deflected by a magnetic field, and that their negative charge was not a separate phenomenon. While supporters of the aetherial theory accepted the possibility that negatively charged particles are produced in Crookes tubes, they believed that they are a mere by-product and that the cathode rays themselves are immaterial. Thomson set out to investigate whether or not he could actually separate the charge from the rays. Thomson constructed a Crookes tube with an electrometer set to one side, out of the direct path of the cathode rays.

A beam of cathode rays in a vacuum tube bent into a circle by a magnetic field generated by a Helmholtz coil. Cathode rays are normally invisible; in this demonstration Teltron tube enough residual gas has been left that the gas atoms glow from luminescence when struck by the fast-moving electrons. Cathode rays (electron beam or e-beam) are streams of electrons observed in discharge tubes. If an evacuated glass tube is equipped with two electrodes and a voltage is applied, glass behind the positive electrode is observed to glow, due to electrons emitted from the cathode (the electrode connected to the negative terminal of the voltage supply). They were first observed in 1869 by German physicist Julius Plücker and Johann Wilhelm Hittorf, and were named in 1876 by Eugen Goldstein Kathodenstrahlen, or cathode rays.

The dynamid atomic model, by Philipp Lenard, 1903 As a physicist, Lenard's major contributions were in the study of cathode rays, which he began in 1888. Prior to his work, cathode rays were produced in primitive, partially evacuated glass tubes that had metallic electrodes in them, across which a high voltage could be placed. Cathode rays were difficult to study using this arrangement, because they were inside sealed glass tubes, difficult to access, and because the rays were in the presence of air molecules. Lenard overcame these problems by devising a method of making small metallic windows in the glass that were thick enough to be able to withstand the pressure differences, but thin enough to allow passage of the rays.

Hermann Starke conducted similar measurements in 1903, although he used cathode rays limited to 0.3c. The results that he obtained were interpreted by him as being in agreement with those of Kaufmann.

In early November, he was repeating an experiment with one of Lenard's tubes in which a thin aluminium window had been added to permit the cathode rays to exit the tube but a cardboard covering was added to protect the aluminium from damage by the strong electrostatic field that produces the cathode rays. Röntgen knew that the cardboard covering prevented light from escaping, yet he observed that the invisible cathode rays caused a fluorescent effect on a small cardboard screen painted with barium platinocyanide when it was placed close to the aluminium window. It occurred to Röntgen that the Crookes–Hittorf tube, which had a much thicker glass wall than the Lenard tube, might also cause this fluorescent effect. In the late afternoon of 8 November 1895, Röntgen was determined to test his idea.

From 1886 to 1888 he had studied in the Hermann Helmholtz laboratory in Berlin, where he became familiar with the cathode rays generated in vacuum tubes when a voltage was applied across separate electrodes, as previously studied by Heinrich Hertz and Philipp Lenard. His letter of January 6, 1893 (describing his discovery as "electric photography") to The Physical Review was duly published and an article entitled Without Lens or Light, Photographs Taken With Plate and Object in Darkness appeared in the San Francisco Examiner. Starting in 1888, Philipp Lenard conducted experiments to see whether cathode rays could pass out of the Crookes tube into the air. He built a Crookes tube with a "window" in the end made of thin aluminum, facing the cathode so the cathode rays would strike it (later called a "Lenard tube").

Thomson first investigated the magnetic deflection of cathode rays. Cathode rays were produced in the side tube on the left of the apparatus and passed through the anode into the main bell jar, where they were deflected by a magnet. Thomson detected their path by the fluorescence on a squared screen in the jar. He found that whatever the material of the anode and the gas in the jar, the deflection of the rays was the same, suggesting that the rays were of the same form whatever their origin.

Atoms were thought to be the smallest possible division of matter until 1897 when J. J. Thomson discovered the electron through his work on cathode rays. A Crookes tube is a sealed glass container in which two electrodes are separated by a vacuum. When a voltage is applied across the electrodes, cathode rays are generated, creating a glowing patch where they strike the glass at the opposite end of the tube. Through experimentation, Thomson discovered that the rays could be deflected by an electric field (in addition to magnetic fields, which was already known).

In the last years of the 19th century, scientists frequently experimented with the cathode-ray tube, which by then had become a standard piece of laboratory equipment. A common practice was to aim the cathode rays at various substances and to see what happened. Wilhelm Röntgen had a screen coated with barium platinocyanide that would fluoresce when exposed to cathode rays. On 8 November 1895, he noticed that even though his cathode-ray tube was not pointed at his screen, which was covered in black cardboard, the screen still fluoresced.

The International Year Book. (1900). New York: Dodd, Mead & Company. p. 659. Thomson deduced that the ejected particles, which he called corpuscles, were of the same nature as cathode rays. These particles later became known as the electrons.

In 1858, Gassiot, in his Bakerian lecture, reported deflections of electrical discharges in rarefied gases both by magnetism and electrostatics. Though this was an early observation of the phenomenon of cathode rays, Julius Plücker is usually credited with their discovery.

The gas ionization (or cold cathode) method of producing cathode rays used in Crookes tubes was unreliable, because it depended on the pressure of the residual air in the tube. Over time, the air was absorbed by the walls of the tube, and it stopped working. A more reliable and controllable method of producing cathode rays was investigated by Hittorf and Goldstein, and rediscovered by Thomas Edison in 1880. A cathode made of a wire filament heated red hot by a separate current passing through it would release electrons into the tube by a process called thermionic emission.

E. Goldstein (May 4, 1876) "Vorläufige Mittheilungen über elektrische Entladungen in verdünnten Gasen" (Preliminary communications on electric discharges in rarefied gases), Monatsberichte der Königlich Preussischen Akademie der Wissenschaften zu Berlin (Monthly Reports of the Royal Prussian Academy of Science in Berlin), 279-295. He discovered several important properties of cathode rays, which contributed to their later identification as the first subatomic particle, the electron. He found that cathode rays were emitted perpendicularly from a metal surface, and carried energy. He attempted to measure their velocity by the Doppler shift of spectral lines in the glow emitted by Crookes tubes.

Goldstein used a gas discharge tube which had a perforated cathode. The rays are produced in the holes (canals) in the cathode and travels in a direction opposite to the "cathode rays," which are streams of electrons. Goldstein called these positive rays "Kanalstrahlen" - canal rays.

He estimated the mass of cathode rays by measuring the heat generated when the rays hit a thermal junction and comparing this with the magnetic deflection of the rays. His experiments suggested not only that cathode rays were over 1,000 times lighter than the hydrogen atom, but also that their mass was the same in whichever type of atom they came from. He concluded that the rays were composed of very light, negatively charged particles which were a universal building block of atoms. He called the particles "corpuscles", but later scientists preferred the name electron which had been suggested by George Johnstone Stoney in 1891, prior to Thomson's actual discovery.

In April 1897, Thomson had only early indications that the cathode rays could be deflected electrically (previous investigators such as Heinrich Hertz had thought they could not be). A month after Thomson's announcement of the corpuscle, he found that he could reliably deflect the rays by an electric field if he evacuated the discharge tube to a very low pressure. By comparing the deflection of a beam of cathode rays by electric and magnetic fields he obtained more robust measurements of the mass-to-charge ratio that confirmed his previous estimates. This became the classic means of measuring the charge-to-mass ratio of the electron.

The first true electronic vacuum tubes, invented in 1904 by John Ambrose Fleming, used this hot cathode technique, and they superseded Crookes tubes. These tubes didn't need gas in them to work, so they were evacuated to a lower pressure, around 10−9 atm (10−4 Pa). The ionization method of creating cathode rays used in Crookes tubes is today only used in a few specialized gas discharge tubes such as krytrons. In 1906, Lee De Forest found that a small voltage on a grid of metal wires between the cathode and anode could control a much larger current in a beam of cathode rays passing through a vacuum tube.

Retrieved September 4, 2019. She's a half- human/half-Martian who gains superpowers, including telekinesis and the ability to wish things into existence, after accidentally being exposed to cathode rays. Her real name is Jane Gem35. She travels to Earth, and steals three million dollars in gold.

At this time, atoms were the smallest particles known, and were believed to be indivisible. What carried electric currents was a mystery. During the last quarter of the 19th century, many historic experiments were done with Crookes tubes to determine what cathode rays were. There were two theories.

Several scientists, such as William Prout and Norman Lockyer, had suggested that atoms were built up from a more fundamental unit, but they envisioned this unit to be the size of the smallest atom, hydrogen. Thomson in 1897 was the first to suggest that one of the fundamental units was more than 1,000 times smaller than an atom, suggesting the subatomic particle now known as the electron. Thomson discovered this through his explorations on the properties of cathode rays. Thomson made his suggestion on 30 April 1897 following his discovery that cathode rays (at the time known as Lenard rays) could travel much further through air than expected for an atom-sized particle.

In his Faraday Memorial Lecture in 1881, the German Hermann von Helmholtz asserted that Faraday's laws of electrochemistry hinted at the atomic structure of matter. If the chemical elements were distinguishable from one another by simple ratios of mass, and if the same amounts of electricity deposited amounts of these elements upon the poles in ratios, then electricity must also come in as discrete units, later named electrons. In the late nineteenth century, the nature of the energy emitted by the discharge between high-voltage electrodes inside an evacuated tube—cathode rays—attracted the attention of many physicists. While the Germans thought cathode rays were waves, the British and the French believed they were particles.

Earlier, physicists debated whether cathode rays were immaterial like light ("some process in the aether") or were "in fact wholly material, and ... mark the paths of particles of matter charged with negative electricity", quoting Thomson. The aetherial hypothesis was vague, but the particle hypothesis was definite enough for Thomson to test.

Goldstein also used discharge tubes to investigate comets. An object, such as a small ball of glass or iron, placed in the path of cathode rays produces secondary emissions to the sides, flaring outwards in a manner reminiscent of a comet's tail. See the work of Hedenus for pictures and additional information.

Julius Plücker (16 June 1801 – 22 May 1868) was a German mathematician and physicist. He made fundamental contributions to the field of analytical geometry and was a pioneer in the investigations of cathode rays that led eventually to the discovery of the electron. He also vastly extended the study of Lamé curves.

Since the electron mass determines a number of observed effects in atomic physics, there are potentially many ways to determine its mass from an experiment, if the values of other physical constants are already considered known. Historically, the mass of the electron was determined directly from combining two measurements. The mass-to-charge ratio of the electron was first estimated by Arthur Schuster in 1890 by measuring the deflection of "cathode rays" due to a known magnetic field in a cathode ray tube. It was seven years later that J. J. Thomson showed that cathode rays consist of streams of particles, to be called electrons, and made more precise measurements of their mass-to-charge ratio again using a cathode ray tube.

Guye and Lavanchy's evaluation of 25 data points for each theory. In 1915, Charles-Eugène Guye and Charles Lavanchy measured the deflection of cathode rays at 0.25c–0.5c. They used a tube with a cathode and anode in order to accelerate the rays. A diaphragm at the anode produced a beam which was deflected.

Any vacuum tube which operates using a focused beam of electrons, originally called cathode rays, is known as a cathode ray tube (CRT). These are usually seen as display devices as used in older (i.e., non-flat panel) television receivers and computer displays. The camera pickup tubes described in this article are also CRTs, but they display no image.

Subsequently, the magnets bent the cathode rays elsewhere from the screen, along a magnetic field, and created variations with the vibrant colours. This production technique was utilized by early video artists since machines that colourised video images had not yet been invented. The projected images were developed and created on Final Cut Pro and Adobe After Effects.

In Encyclopædia Britannica. Retrieved November 20, 2010, from Encyclopædia Britannica Online However this required expensive quartz optics, due to the absorption of UV by glass. It was believed that obtaining an image with sub-micrometer information was not possible due to this wavelength constraint. In 1858, Plücker observed the deflection of "cathode rays" (electrons) by magnetic fields.

Like a wave, cathode rays travel in straight lines, and produce a shadow when obstructed by objects. Ernest Rutherford demonstrated that rays could pass through thin metal foils, behavior expected of a particle. These conflicting properties caused disruptions when trying to classify it as a wave or particle. Crookes insisted it was a particle, while Hertz maintained it was a wave.

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.

Stark's 1913 model of triatomic hydrogen J. J. Thomson observed H3+ while experimenting with positive rays. He believed that it was an ionised form of H3 from about 1911. He believed that H3 was a stable molecule and wrote and lectured about it. He stated that the easiest way to make it was to target potassium hydroxide with cathode rays.

In 1919, when Czernowitz became a Romanian university, Geitler relocated to Graz, where he taught classes at the Technische Universität Graz. Among his scientific research were studies that explained differences between x-rays and cathode rays. His best known publication was Elektromagnetische Schwingungen und Wellen, ("Electromagnetic oscillations and waves") (1905).Google Books Elektromagnetische Schwingungen und Well He was a cousin to physicist Heinrich Hertz (1857-1894).

University of Bonn researchers made fundamental contributions in the sciences and the humanities. In physics researchers developed the quadrupole ion trap and the Geissler tube, discovered radio waves, were instrumental in describing cathode rays and developed the variable star designation. In chemistry researchers made significant contributions to the understanding of alicyclic compounds and Benzene. In material science researchers have been instrumental in describing the lotus effect.

Wilhelm Röntgen received the first Physics Prize for his discovery of X-rays. Once the Nobel Foundation and its guidelines were in place, the Nobel Committees began collecting nominations for the inaugural prizes. Subsequently, they sent a list of preliminary candidates to the prize-awarding institutions. The Nobel Committee's Physics Prize shortlist cited Wilhelm Röntgen's discovery of X-rays and Philipp Lenard's work on cathode rays.

His cousin, Kirill Fedorovich Nesturkh, then a young physicist, invited him to attend the defense of the dissertation of Abram Fedorovich Ioffe. Physics lecturer Vladimir Konstantinovich Lebedinskiy had explained to Theremin the dispute over Ioffe's work on the electron. On 9 May 1913 Theremin and his cousin attended Ioffe's dissertation defense. Ioffe's subject was on the elementary photoelectric effect, the magnetic field of cathode rays and related investigations.

Born in Lille, France, Perrin attended the École Normale Supérieure, the elite grande école in Paris. He became an assistant at the school during the period of 1894–97 when he began the study of cathode rays and X-rays. He was awarded the degree of docteur ès sciences (PhD) in 1897. In the same year he was appointed as a lecturer in physical chemistry at the Sorbonne, Paris.

The anode is at the bottom wire. British chemist and physicist William Crookes is noted for his cathode ray studies, fundamental in the development of atomic physics. His researches on electrical discharges through a rarefied gas led him to observe the dark space around the cathode, now called the Crookes dark space. He demonstrated that cathode rays travel in straight lines and produce phosphorescence and heat when they strike certain materials.

Cathode ray tube #12, Ivan Puluj design, ca 1896 Puluj's apparatus for determining the mechanical equivalent of heatPuluj did heavy research into cathode rays, publishing several papers about those rays between 1880 and 1882. In 1881 as a result of experiments into what he called cold light Prof. Puluj developed the Puluj lamp;Puluj- Röhre, 1870. uibk.ac.at it was awarded the Silver Medal at the International Electrotechnical Exhibition in Paris, 1881.

Replica of F. W. Aston's third mass spectrograph. NIH in 1975 The history of mass spectrometry has its roots in physical and chemical studies regarding the nature of matter. The study of gas discharges in the mid 19th century led to the discovery of anode and cathode rays, which turned out to be positive ions and electrons. Improved capabilities in the separation of these positive ions enabled the discovery of stable isotopes of the elements.

With no obstructions, these low mass particles were accelerated to high velocities by the voltage between the electrodes. These were the cathode rays. When they reached the anode end of the tube, they were traveling so fast that, although they were attracted to it, they often flew past the anode and struck the back wall of the tube. When they struck atoms in the glass wall, they excited their orbital electrons to higher energy levels.

He also received the Rumford Medal of the British Royal Society in 1896, jointly with Philipp Lenard, who had already shown that a portion of the cathode rays could pass through a thin film of a metal such as aluminum. Röntgen published a total of three papers on X-rays between 1895 and 1897.Wilhelm Röntgen, "Ueber eine neue Art von Strahlen. Vorläufige Mitteilung", in: Aus den Sitzungsberichten der Würzburger Physik.-medic.

Pump technology hit a plateau until Geissler and Sprengle in the mid 19th century, who finally gave access to the high-vacuum regime. This led to the study of electrical discharges in vacuum, discovery of cathode rays, discovery of X-rays and the discovery of the electron. The photoelectric effect was observed in high vacuum, which was a key discovery that lead to the formulation of quantum mechanics and much of modern physics.

William Thomson, "On Vortex Atoms", Proceedings of the Royal Society of Edinburgh, V6, pp. 94–105 (1867) {reprinted in Philosophical Magazine, V34, pp. 15–24 (1867)}. Then shortly before 1900, as scientists still debated over the very existence of atoms, J. J. ThomsonJ. J. Thomson, "Cathode Rays", Philosophical Magazine, S5, V44, p. 293 (1897). and Ernest RutherfordErnest Rutherford, "Uranium Radiation and the Electrical Conduction ", Philosophical Magazine, S5, V47, pp. 109–163 (Jan 1899).

In 1905 he investigated cathode rays together with Wilhelm Wien. Afterwards he investigated some topics on special relativity and wrote in 1907 an important work on the optics of moving bodies. In 1908 he wrote several works together with Einstein on the basic electromagnetic equations, which was aimed to replace the four-dimensional formulation of the electrodynamics by Minkowski by a simpler, classical formulation. Both Laub and Einstein discounted the spacetime formalism as too complicated.

16, Wallstein, pp. 122-123, 2007, In 1907, Bestelmeyer questioned the accuracy of the measurements by Walter Kaufmann regarding the speed dependence of the electromagnetic mass. Bestelmeyer used a velocity filter for his own experiments on cathode rays, and this method was later also used by Alfred Bucherer. While Bucherer saw the results of his experiments as a confirmation of special relativity, his methods were criticized by Bestelmeyer, thus a polemical dispute between these two researchers arose.

In 1871, he authored a scientific paper suggesting that cathode rays were streams of particles of electricity. Varley believed cathode radiation was caused by the collision of particles. His belief was based on the idea that because the rays were deflected in the presence of a magnet, these particles have to be considered carriers of an electric charge. This led him to believe that the electrically charged particles should be deflected by the presence of an electric field.

He also showed they were identical with particles given off by photoelectric and radioactive materials. It was quickly recognized that they are the particles that carry electric currents in metal wires, and carry the negative electric charge of the atom. Thomson was given the 1906 Nobel prize for physics for this work. Philipp Lenard also contributed a great deal to cathode ray theory, winning the Nobel prize for physics in 1905 for his research on cathode rays and their properties.

130px In 1896, Wright had been experimenting with Crookes tube of spherical shape to generate long exposure x-ray photographs. He believed the cathode rays exuded in the sphere were dynamically different from those discovered by Phillipp Lenard only a year earlier. For the future, Wright intended to research aluminum's behavior under an x-ray and its effect paired with an electric current. Wright saw the possibility of using the rays for surgical and medical fields, predicting the rise of x-ray technology.

Having made a window for the rays, he could pass them out into the laboratory, or, alternatively, into another chamber that was completely evacuated. These windows have come to be known as Lenard windows. He was able to conveniently detect the rays and measure their intensity by means of paper sheets coated with phosphorescent materials. Lenard observed that the absorption of cathode rays was, to first order, proportional to the density of the material they were made to pass through.

Jean Perrin in 1908 In 1895, Perrin showed that cathode rays were of negative electric charge in nature. He determined Avogadro's number (now known as the Avogadro constant) by several methods. He explained solar energy as due to the thermonuclear reactions of hydrogen. After Albert Einstein published (1905) his theoretical explanation of Brownian motion in terms of atoms, Perrin did the experimental work to test and verify Einstein's predictions, thereby settling the century-long dispute about John Dalton's atomic theory.

A pioneer of vacuum tubes, Crookes invented the Crookes tube - an early experimental discharge tube, with partial vacuum with which he studied the behavior of cathode rays. With the introduction of spectrum analysis by Robert Bunsen and Gustav Kirchhoff (1859-1860), Crookes applied the new technique to the study of selenium compounds. Bunsen and Kirchhoff had previously used spectroscopy as a means of chemical analysis to discover caesium and rubidium. In 1861, Crookes used this process to discover thallium in some seleniferous deposits.

The Geiger–Marsden experiment: Left: Expected results: alpha particles passing through the plum pudding model of the atom with negligible deflection. Right: Observed results: a small portion of the particles were deflected by the concentrated positive charge of the nucleus. In 1897, J. J. Thomson discovered that cathode rays are not electromagnetic waves but made of particles that are 1,800 times lighter than hydrogen (the lightest atom). Therefore, they were not atoms, but a new particle, the first subatomic particle to be discovered.

After receiving her PhD in 1908, Wick became an instructor of physics at Simmons College. She began teaching at Vassar College in 1910, starting off as an instructor, and becoming an assistant professor in 1915, an associate professor in 1919, and a professor in 1922. Wick became the head of Vassar's physics department in 1939. Wick continued her research on luminescence by studying the luminescent properties of various media such as cathode rays, X-rays, radium rays, heat, and friction.

It later came to be known as radon. Rutherford identified beta rays as cathode rays (electrons), and hypothesised—and in 1909 with Thomas Royds proved—that alpha particles were helium nuclei. Observing the radioactive disintegration of elements, Rutherford and Soddy classified the radioactive products according to their characteristic rates of decay, introducing the concept of a half-life. In 1903, Soddy and Margaret Todd applied the term "isotope" to atoms that were chemically and spectroscopically indistinct but had different radioactive half-lives.

Angelo Battelli (28 March 1862 – 11 December 1916) was an Italian scientist, notable for having measured temperatures and heats of fusion of non-metallic substances, metallic conductivities and thermoelectric effects in magnetic metals, and the Thomson effect. He investigated osmotic pressures, surface tensions, and physical properties of carbon disulfide (CS2), water (H2O), and alcohols, especially their vapor pressures, critical points, and densities. He studied X-rays and cathode rays. He investigated the resistance of solenoids to high-frequency alternating currents.

Ultraviolet light and cathode rays have no fluorescent effect on changbaiite and this is not soluble in hydrochloric acid, nitric acid or sulphuric acid but conditionally less soluble in hot phosphoric acid. Changbaiite has a hardness of 472.4 kg/mm2 on the Vickers hardness scale and 5.3 on mohs scale. In an optical spectrum changbaiite is uniaxial positive and it can be biaxial. Changbaiite reflectance, which is the fraction of incident radiation reflected by a surface, is 15.86 at 546 nm.

Thus the ionized air was electrically conductive and an electric current flowed through the tube. Geissler tubes had enough air in them that the electrons could only travel a tiny distance before colliding with an atom. The electrons in these tubes moved in a slow diffusion process, never gaining much speed, so these tubes didn't produce cathode rays. Instead, they produced a colorful glow discharge (as in a modern neon light), caused when the electrons struck gas atoms, exciting their orbital electrons to higher energy levels.

In the mid-nineteenth century, Julius Plücker investigated the light emitted in discharge tubes (Crookes tubes) and the influence of magnetic fields on the glow. Later, in 1869, Johann Wilhelm Hittorf studied discharge tubes with energy rays extending from a negative electrode, the cathode. These rays produced a fluorescence when they hit a tube's glass walls, and when interrupted by a solid object they cast a shadow. In the 1870s, Goldstein undertook his own investigations of discharge tubes and named the light emissions studied by others Kathodenstrahlen, or cathode rays.

In 1886, he discovered that tubes with a perforated cathode also emit a glow at the cathode end. Goldstein concluded that in addition to the already-known cathode rays, later recognized as electrons moving from the negatively charged cathode toward the positively charged anode, there is another ray that travels in the opposite direction. Because these latter rays passed through the holes, or channels, in the cathode, Goldstein called them Kanalstrahlen, or canal rays. They are composed of positive ions whose identity depends on the residual gas inside the tube.

The N ray affair occurred shortly after a series of major breakthroughs in experimental physics. Victor Schumann discovered vacuum ultraviolet radiation in 1893, Wilhelm Röntgen discovered X-rays in 1895, Henri Becquerel discovered radioactivity in 1896, and, in 1897, J. J. Thomson discovered electrons, showing that they were the constituents of cathode rays. This created an expectation within the scientific community that other forms of radiation might be discovered. At this time, Prosper-René Blondlot was a professor of physics at the University of Nancy studying electromagnetic radiation.

This effect was used by Ferdinand Braun in 1897 to build simple cathode-ray oscilloscope (CRO) measuring devices. In 1891, Riecke noticed that the cathode rays could be focused by magnetic fields, allowing for simple electromagnetic lens designs. In 1926, Hans Busch published work extending this theory and showed that the lens maker's equation could, with appropriate assumptions, be applied to electrons. In 1928, at the Technical University of Berlin, Adolf Matthias, Professor of High Voltage Technology and Electrical Installations, appointed Max Knoll to lead a team of researchers to advance the CRO design.

Working at the Cavendish Laboratory, established by Maxwell, J. J. Thompson directed a dedicate experiment demonstrating that cathode rays were in fact negatively charged particles, now called electrons. The experiment enabled Thompson to calculate the ratio between the magnitude of the charge and the mass of the particle (q/m). In addition, because the ratio was the same regardless of the metal used, Thompson concluded that electrons must be a constituent of all atoms. Although the atoms of each chemical elements have different numbers of electrons, all electrons are identical.

The day was officially confirmed by the three founding societies during the annual RSNA meeting in Chicago on November 28, 2011. On November 8, 1895 Wilhelm Conrad Röntgen discovered x-rays by chance while investigating cathode rays, effectively laying the foundation for the medical discipline of radiology. This discovery would grow to include various methods of imaging and establish itself as a crucial element of modern medicine. The 8 of November was eventually chosen as the appropriate day to mark the celebrations which are observed by radiological societies the world over.

Alpha, beta, and gamma are the first three letters of the Greek alphabet. In 1900, Becquerel measured the mass-to-charge ratio () for beta particles by the method of J.J. Thomson used to study cathode rays and identify the electron. He found that for a beta particle is the same as for Thomson's electron, and therefore suggested that the beta particle is in fact an electron. In 1901, Rutherford and Frederick Soddy showed that alpha and beta radioactivity involves the transmutation of atoms into atoms of other chemical elements.

Unlike Kaufmann and Bucherer, Karl Erich Hupka (1909) used cathode rays at 0.5c for his measurements. The radiation (generated at a copper cathode) was strongly accelerated by the field between cathode and anode in a highly evacuated discharge tube. The anode serving as a diaphragm was passed by the ray with constant velocity and drew the shadow image of two Wollaston wires on a phosphorescent screen behind a second diaphragm. If a current was generated behind this diaphragm, then the ray was deflected and the shadow image was displaced.

In this "plum pudding model", the electrons were seen as embedded in the positive charge like raisins in a plum pudding (although in Thomson's model they were not stationary, but orbiting rapidly)., p. 324: "Thomson's model, then, consisted of a uniformly charged sphere of positive electricity (the pudding), with discrete corpuscles (the plums) rotating about the center in circular orbits, whose total charge was equal and opposite to the positive charge." Thomson made the discovery around the same time that Walter Kaufmann and Emil Wiechert discovered the correct mass to charge ratio of these cathode rays (electrons).

This appeared to contradict the idea that they were some sort of electromagnetic radiation. He also showed that the rays could pass through some inches of air of a normal density, and appeared to be scattered by it, implying that they must be particles that were even smaller than the molecules in air. He confirmed some of J.J. Thomson's work, which eventually arrived at the understanding that cathode rays were streams of negatively charged energetic particles. He called them quanta of electricity or for short quanta, after Helmholtz, while J.J. Thomson proposed the name corpuscles, but eventually electrons became the everyday term.

Passing alpha particles through a very thin glass window and trapping them in a discharge tube allowed researchers to study the emission spectrum of the captured particles, and ultimately proved that alpha particles are helium nuclei. Other experiments showed beta radiation, resulting from decay and cathode rays, were high-speed electrons. Likewise, gamma radiation and X-rays were found to be high-energy electromagnetic radiation. The relationship between the types of decays also began to be examined: For example, gamma decay was almost always found to be associated with other types of decay, and occurred at about the same time, or afterwards.

The cathode ray tube by which J. J. Thomson demonstrated that cathode rays could be deflected by a magnetic field. The Thomson Medal and Prize is an award which has been made, originally only biennially in even-numbered years, since 2008 by the British Institute of Physics for "distinguished research in atomic (including quantum optics) or molecular physics". It is named after Nobel prizewinner Sir J. J. Thomson, the British physicist who demonstrated the existence of electrons, and comprises a silver medal and a prize of £1000. Not to be confused with the J. J. Thomson IET Achievement Medal for electronics.

On his death in 1838 it passed to his second cousin Archibald Douglas Campbell (died 1868) of the lineage of Douglas of Mains, who adopted the name of Campbell, a pre-requisite of Blythswood ownerships. The house also contained a well-known laboratory that was used by Archibald Campbell, 1st Baron Blythswood from 1892 to 1905 to experiment into many areas at the borders of physics, including the use of cathode rays, X-rays, spectroscopy and radioactivity. The house remained the seat of the Lords Blythswood until its demolition in 1935. Five years later the family title became extinct.

There was even speculation that even God could not create a vacuum if he wanted and the 1277 Paris condemnations of Bishop Etienne Tempier, which required there to be no restrictions on the powers of God, led to the conclusion that God could create a vacuum if he so wished. Jean Buridan reported in the 14th century that teams of ten horses could not pull open bellows when the port was sealed. The Crookes tube, used to discover and study cathode rays, was an evolution of the Geissler tube. The 17th century saw the first attempts to quantify measurements of partial vacuum.

The main problem of Kaufmann's experiments was his use of parallel magnetic and electric fields, as pointed out by Adolf Bestelmeyer (1907). Using a method based on perpendicular magnetic and electric fields (introduced by J. J. Thomson and further developed to a velocity filter by Wilhelm Wien), Bestelmeyer obtained considerably different values for the charge-to-mass ratio for cathode rays up to 0.3c. However, Bestelmeyer added that his experiment was not precise enough to provide a definite decision between the theories. Therefore, Alfred Bucherer (1908) conducted a precise measurement using a velocity filter similar to Bestelmeyer's.

When the electrons returned to their original energy level, they released the energy as light, causing the glass to fluoresce, usually a greenish or bluish color. Later researchers painted the inside back wall with fluorescent chemicals such as zinc sulfide, to make the glow more visible. Cathode rays themselves are invisible, but this accidental fluorescence allowed researchers to notice that objects in the tube in front of the cathode, such as the anode, cast sharp-edged shadows on the glowing back wall. In 1869, German physicist Johann Hittorf was first to realize that something must be traveling in straight lines from the cathode to cast the shadows.

The electron charge-to-mass quotient, -e/m_{e}, is a quantity that may be measured in experimental physics. It bears significance because the electron mass me is difficult to measure directly, and is instead derived from measurements of the elementary charge e and e/m_{e}. It also has historical significance; the Q/m ratio of the electron was successfully calculated by J. J. Thomson in 1897—and more successfully by Dunnington, which involves the angular momentum and deflection due to a perpendicular magnetic field. Thomson's measurement convinced him that cathode rays were particles, which were later identified as electrons, and he is generally credited with their discovery.

Simplified representation of an anode ray tube, showing the rays to the right of the perforated cathode 210x210px Goldstein used a gas- discharge tube which had a perforated cathode. When an electrical potential of several thousand volts is applied between the cathode and anode, faint luminous "rays" are seen extending from the holes in the back of the cathode. These rays are beams of particles moving in a direction opposite to the "cathode rays", which are streams of electrons which move toward the anode. Goldstein called these positive rays Kanalstrahlen, "channel rays" or "canal rays", because they were produced by the holes or channels in the cathode.

Ernest Rutherford and his colleagues Hans Geiger and Ernest Marsden came to have doubts about the Thomson model after they encountered difficulties when they tried to build an instrument to measure the charge-to-mass ratio of alpha particles (these are positively-charged particles emitted by certain radioactive substances such as radium). The alpha particles were being scattered by the air in the detection chamber, which made the measurements unreliable. Thomson had encountered a similar problem in his work on cathode rays, which he solved by creating a near-perfect vacuum in his instruments. Rutherford didn't think he'd run into this same problem because alpha particles are much heavier than electrons.

The alpha particles were being scattered by the air in the detection chamber, which made the measurements unreliable. Thomson had encountered a similar problem in his work on cathode rays, which he solved by creating a near-perfect vacuum in his instruments. Rutherford didn't think he'd run into this same problem because alpha particles are much heavier than electrons. According to Thomson's model of the atom, the positive charge in the atom is not concentrated enough to produce an electric field strong enough to deflect an alpha particle, and the electrons are so lightweight they should be pushed aside effortlessly by the much heavier alpha particles.

Kristian Birkeland and his magnetized terrella experiment, which led him to surmise that charged particles interacting with the Earth's magnetic field were the cause of the aurora. Kristian Birkeland was a Norwegian physicist who, around 1895, tried to explain why the lights of the polar aurora appeared only in regions centered at the magnetic poles. He simulated the effect by directing cathode rays (later identified as electrons) at a terella in a vacuum tank, and found they indeed produced a glow in regions around the poles of the terrella. Because of residual gas in the chamber, the glow also outlined the path of the particles.

In 1897, English physicist J. J. Thomson was able, in his three famous experiments, to deflect cathode rays, a fundamental function of the modern cathode ray tube (CRT). The earliest version of the CRT was invented by the German physicist Ferdinand Braun in 1897 and is also known as the "Braun" tube.Ferdinand Braun (1897) "Ueber ein Verfahren zur Demonstration und zum Studium des zeitlichen Verlaufs variabler Ströme" (On a process for the display and study of the course in time of variable currents), Annalen der Physik und Chemie, 3rd series, 60 : 552–59. It was a cold-cathode diode, a modification of the Crookes tube, with a phosphor-coated screen.

Example of a Crookes Tube, a type of discharge tube that emitted X-rays Before their discovery in 1895, X-rays were just a type of unidentified radiation emanating from experimental discharge tubes. They were noticed by scientists investigating cathode rays produced by such tubes, which are energetic electron beams that were first observed in 1869. Many of the early Crookes tubes (invented around 1875) undoubtedly radiated X-rays, because early researchers noticed effects that were attributable to them, as detailed below. Crookes tubes created free electrons by ionization of the residual air in the tube by a high DC voltage of anywhere between a few kilovolts and 100 kV.

Röntgen received the first Nobel Prize in Physics for his discovery. There are conflicting accounts of his discovery because Röntgen had his lab notes burned after his death, but this is a likely reconstruction by his biographers: Röntgen was investigating cathode rays from a Crookes tube which he had wrapped in black cardboard so that the visible light from the tube would not interfere, using a fluorescent screen painted with barium platinocyanide. He noticed a faint green glow from the screen, about 1 meter away. Röntgen realized some invisible rays coming from the tube were passing through the cardboard to make the screen glow.

Kristian Birkeland Birkeland organized several expeditions to Norway's high-latitude regions where he established a network of observatories under the auroral regions to collect magnetic field data. The results of the Norwegian Polar Expedition conducted from 1899 to 1900 contained the first determination of the global pattern of electric currents in the polar region from ground magnetic field measurements. The discovery of X-rays inspired Birkeland to develop vacuum chambers to study the influence of magnets on cathode rays. Birkeland noticed that an electron beam directed toward a magnetised terrella was guided toward the magnetic poles and produced rings of light around the poles and concluded that the aurora could be produced in a similar way.

In 1897, J. J. Thomson, an English physicist, in his three famous experiments was able to deflect cathode rays, a fundamental function of the modern Cathode Ray Tube (CRT). The earliest version of the CRT was invented by the German physicist Karl Ferdinand Braun in 1897 and is also known as the Braun tube.Ferdinand Braun (1897) "Ueber ein Verfahren zur Demonstration und zum Studium des zeitlichen Verlaufs variabler Ströme" (On a process for the display and study of the course in time of variable currents), Annalen der Physik und Chemie, 3rd series, 60 : 552-559. It was a cold-cathode diode, a modification of the Crookes tube with a phosphor-coated screen.

Crookes and Arthur Schuster believed they were particles of "radiant matter," that is, electrically charged atoms. German scientists Eilhard Wiedemann, Heinrich Hertz and Goldstein believed they were "aether waves", some new form of electromagnetic radiation, and were separate from what carried the electric current through the tube. The debate was resolved in 1897 when J. J. Thomson measured the mass of cathode rays, showing they were made of particles, but were around 1800 times lighter than the lightest atom, hydrogen. Therefore, they were not atoms, but a new particle, the first subatomic particle to be discovered, which he originally called "corpuscle" but was later named electron, after particles postulated by George Johnstone Stoney in 1874.

His invention, called the triode, was the first device that could amplify electric signals, and revolutionized electrical technology, creating the new field of electronics. Vacuum tubes made radio and television broadcasting possible, as well as radar, talking movies, audio recording, and long distance telephone service, and were the foundation of consumer electronic devices until the 1960s, when the transistor brought the era of vacuum tubes to a close. Cathode rays are now usually called electron beams. The technology of manipulating electron beams pioneered in these early tubes was applied practically in the design of vacuum tubes, particularly in the invention of the cathode ray tube (CRT) by Ferdinand Braun in 1897, which was used in television sets and oscilloscopes.

Philipp Eduard Anton von Lenard (; 7 June 1862 – 20 May 1947) was a Hungarian- born German physicist and the winner of the Nobel Prize for Physics in 1905 for his work on cathode rays and the discovery of many of their properties. One of his most important contributions was the experimental realization of the photoelectric effect. He discovered that the energy (speed) of the electrons ejected from a cathode depends only on the wavelength, and not the intensity of, the incident light. Lenard was a nationalist and anti-Semite; as an active proponent of the Nazi ideology, he supported Adolf Hitler in the 1920s and was an important role model for the "Deutsche Physik" movement during the Nazi period.

Although at the time of Millikan's oil-drop experiments it was becoming clear that there exist such things as subatomic particles, not everyone was convinced. Experimenting with cathode rays in 1897, J. J. Thomson had discovered negatively charged 'corpuscles', as he called them, with a charge-to-mass ratio 1840 times that of a hydrogen ion. Similar results had been found by George FitzGerald and Walter Kaufmann. Most of what was then known about electricity and magnetism, however, could be explained on the basis that charge is a continuous variable; in much the same way that many of the properties of light can be explained by treating it as a continuous wave rather than as a stream of photons.

J. C. McLennan, director of the physics laboratory at U of T from 1906 to 1932, undertook studies in atmospheric conductivity and cathode rays, but in 1912 was inspired by the work of Bohr, to conduct research into atomic spectroscopy. He, along with G. M. Shrum, constructed the first machine for the liquification of helium in North America, which was used for cryogenic studies of metals and solid gases. Research into colloid physics in the twenties and thirties by E. F. Burton and his students led to the construction of the first electron microscope in North America. Geophysics research was also undertaken at the U of T at this time by L. Gilchrist.

In the laboratory at his father's house Merton had bombarded various newly discovered phosphorescent powders with cathode rays. He was surprised to find that while all lit brilliantly, the afterglow was brief and feeble. By experiment, he discovered that this was because the excitation and emission lines of the spectra barely overlapped, and that by mixing suitable powders he could increase the afterglow. He realized that persistent afterglow could be got by a double layer of powders, in which the light emitted by the back layer excited the front layer, but as this technique seemed to have no practical use he forgot about it for thirty-three years, until 1938 when Sir Henry Tizard asked if he could achieve such a long afterglow.

In conjunction with his and other earlier experiments on the absorption of the rays in metals, the general realization that electrons were constituent parts of the atom enabled Lenard to claim correctly that for the most part atoms consist of empty space. He proposed that every atom consists of empty space and electrically neutral corpuscules called "dynamids", each consisting of an electron and an equal positive charge. As a result of his Crookes tube investigations, he showed that the rays produced by irradiating metals in a vacuum with ultraviolet light were similar in many respects to cathode rays. His most important observations were that the energy of the rays was independent of the light intensity, but was greater for shorter wavelengths of light.

There are conflicting accounts of his discovery because Röntgen had his lab notes burned after his death, but this is a likely reconstruction by his biographers: Röntgen was investigating cathode rays using a fluorescent screen painted with barium platinocyanide and a Crookes tube which he had wrapped in black cardboard to shield its fluorescent glow. He noticed a faint green glow from the screen, about 1 metre away. Röntgen realized some invisible rays coming from the tube were passing through the cardboard to make the screen glow: they were passing through an opaque object to affect the film behind it. The first radiograph Röntgen discovered X-rays' medical use when he made a picture of his wife's hand on a photographic plate formed due to X-rays.

Sir Joseph John Thomson (18 December 1856 – 30 August 1940) was a British physicist and Nobel Laureate in Physics, credited with the discovery of the electron, the first subatomic particle to be discovered. In 1897, Thomson showed that cathode rays were composed of previously unknown negatively charged particles (now called electrons), which he calculated must have bodies much smaller than atoms and a very large charge-to-mass ratio. Thomson is also credited with finding the first evidence for isotopes of a stable (non- radioactive) element in 1913, as part of his exploration into the composition of canal rays (positive ions). His experiments to determine the nature of positively charged particles, with Francis William Aston, were the first use of mass spectrometry and led to the development of the mass spectrograph.

Taking an X-ray image with early Crookes tube apparatus, late 1800s Radiography's origins and fluoroscopy's origins can both be traced to 8 November 1895, when German physics professor Wilhelm Conrad Röntgen discovered the X-ray and noted that, while it could pass through human tissue, it could not pass through bone or metal. Röntgen referred to the radiation as "X", to indicate that it was an unknown type of radiation. He received the first Nobel Prize in Physics for his discovery. There are conflicting accounts of his discovery because Röntgen had his lab notes burned after his death, but this is a likely reconstruction by his biographers: Röntgen was investigating cathode rays using a fluorescent screen painted with barium platinocyanide and a Crookes tube which he had wrapped in black cardboard to shield its fluorescent glow.

He was a notable scientist and took his wife to Thebes to observe the Transit of Venus in 1874, taking with him a small transit instrument, a 6-inch telescope and a 12-inch telescope, recording the time of first contact, and also observed a white halo, proving an atmosphere around Venus. From 1892 to 1905 the Blythswood Laboratory at his family seat was used to experiment into many areas at the borders of physics, including the use of cathode rays, X-rays, spectroscopy and radioactivity. He designed a speed indicator, which was fitted to ships of the Royal Navy, and carried out studies into the efficiency of aerial propellers some years before the Wright Brothers' first powered flight in 1903. He was elected a Fellow of the Royal Society in May, 1907 and died possessed of the family seat in Renfrewshire and Halliford Manor in Shepperton.

Example of phosphorescence Monochrome monitor Aperture grille CRT phosphors A phosphor, most generally, is a substance that exhibits the phenomenon of luminescence; it emits light when exposed to some type of radiant energy. The term is used both for fluorescent or phosphorescent substances which glow on exposure to ultraviolet or visible light, and cathodoluminescent substances which glow when struck by an electron beam (cathode rays) in a cathode ray tube. When a phosphor is exposed to radiation, the orbital electrons in its molecules are excited to a higher energy level; when they return to their former level they emit the energy as light of a certain color. Phosphors can be classified into two categories: fluorescent substances which emit the energy immediately and stop glowing when the exciting radiation is turned off, and phosphorescent substances which emit the energy after a delay, so they keep glowing after the radiation is turned off, decaying in brightness over a period of milliseconds to days.

The history of quantum chemistry also goes through the 1838 discovery of cathode rays by Michael Faraday, the 1859 statement of the black-body radiation problem by Gustav Kirchhoff, the 1877 suggestion by Ludwig Boltzmann that the energy states of a physical system could be discrete, and the 1900 quantum hypothesis by Max Planck that any energy radiating atomic system can theoretically be divided into a number of discrete energy elements ε such that each of these energy elements is proportional to the frequency ν with which they each individually radiate energy and a numerical value called Planck's constant. Then, in 1905, to explain the photoelectric effect (1839), i.e., that shining light on certain materials can function to eject electrons from the material, Albert Einstein postulated, based on Planck's quantum hypothesis, that light itself consists of individual quantum particles, which later came to be called photons (1926). In the years to follow, this theoretical basis slowly began to be applied to chemical structure, reactivity, and bonding.

Gustave Le Bon, Le Bon constructed a home laboratory in the early 1890s, and in 1896 reported observing "black light", a new kind of radiation that he believed was distinct from, but possibly related to, X-rays and cathode rays. Not the same type of radiation as what is now known as black light, its existence was never confirmed and, similar to N rays, it is now generally understood to be non-existent, but the discovery claim attracted much attention among French scientists at the time, many of whom supported it and Le Bon's general ideas on matter and radiation, and he was even nominated for the Nobel Prize in Physics in 1903. In 1902, Le Bon began a series of weekly luncheons to which he invited prominent intellectuals, nobles and ladies of fashion. The strength of his personal networks is apparent from the guest list: participants included cousins Henri and Raymond Poincaré, Paul Valéry, Alexander Izvolsky, Henri Bergson, Marcellin Berthelot and Aristide Briand.

During the experiment, Röntgen "found that the Crookes tubes he had been using to study cathode rays emitted a new kind of invisible ray that was capable of penetrating through black paper". Learning of Röntgen's discovery from earlier that year during a meeting of the French Academy of Sciences caused Becquerel to be interested, and soon "began looking for a connection between the phosphorescence he had already been investigating and the newly discovered x-rays" of Röntgen, and thought that phosphorescent materials, such as some uranium salts, might emit penetrating X-ray-like radiation when illuminated by bright sunlight. By May 1896, after other experiments involving non-phosphorescent uranium salts, he arrived at the correct explanation, namely that the penetrating radiation came from the uranium itself, without any need for excitation by an external energy source. There followed a period of intense research into radioactivity, including the determination that the element thorium is also radioactive and the discovery of additional radioactive elements polonium and radium by Marie Skłodowska-Curie and her husband Pierre Curie.