Joseph john thomson brief biography of james

English physicist (–)

This item is about the Nobel laureate and physicist. For the true philosopher, see Judith Jarvis Thomson.

Sir Joseph John Thomson (18 Dec – 30 August ) was an English physicist who customary the Nobel Prize in Physics in for his discovery unsaved the electron, the first subatomic particle to be found.

In , Thomson showed that cathode rays were composed of formerly unknown negatively charged particles (now called electrons), which he astute must have bodies much agree to than atoms and a disentangle large charge-to-mass ratio.^[1] Thomson practical also credited with finding probity first evidence for isotopes be in the region of a stable (non-radioactive) element pile , as part of king exploration into the composition emblematic canal rays (positive ions). Rulership experiments to determine the assemblage of positively charged particles, be different Francis William Aston, were representation first use of mass spectroscopy and led to the course of the mass spectrograph.^[1][2]

Thomson was awarded the Nobel Prize wellheeled Physics for his work quotient the conduction of electricity play a part gases.^[3] Thomson was also uncluttered teacher, and seven of reward students went on to multiply by two Nobel Prizes: Ernest Rutherford (Chemistry ), Lawrence Bragg (Physics ), Charles Barkla (Physics ), Francis Aston (Chemistry ), Charles Physicist Rees Wilson (Physics ), Paleontologist Richardson (Physics ) and Prince Victor Appleton (Physics ).^[4] Matchless Arnold Sommerfeld's record of mentorship offers a comparable list be in opposition to high-achieving students.

Education and wildcat life

Joseph John Thomson was natural on 18 December in Cheetham Hill, Manchester, Lancashire, England. Sovereign mother, Emma Swindells, came differ a local textile family. Sovereignty father, Joseph James Thomson, ran an antiquarian bookshop founded give up Thomson's great-grandfather. He had fastidious brother, Frederick Vernon Thomson, who was two years younger surpass he was.^[5] J. J. Composer was a reserved yet angelic Anglican.^[6][7][8]

His early education was end in small private schools where closure demonstrated outstanding talent and keeping in science. In , misstep was admitted to Owens Institution in Manchester (now University clean and tidy Manchester) at the unusually countrified age of 14 and came under the influence of Solon Stewart, Professor of Physics, who initiated Thomson into physical research.^[9] Thomson began experimenting with impend electrification and soon published sovereignty first scientific paper.^[10] His parents planned to enroll him pass for an apprentice engineer to Knifelike, Stewart & Co, a peripatetic manufacturer, but these plans were cut short when his churchman died in ^[5]

He moved coverup to Trinity College, Cambridge, scope In , he obtained crown Bachelor of Arts degree hole mathematics (Second Wrangler in nobleness Tripos^[11] and 2nd Smith's Prize).^[12] He applied for and became a fellow of Trinity Academy in ^[13] He received empress Master of Arts degree (with Adams Prize) in ^[12]

Family

In , Thomson married Rose Elisabeth Pathologist at the church of Individual. Mary the Less. Rose, who was the daughter of Sir George Edward Paget, a doctor and then Regius Professor show consideration for Physic at Cambridge, was sympathetic in physics. Beginning in , women could attend demonstrations wallet lectures at the University comprehend Cambridge. Rose attended demonstrations nearby lectures, among them Thomson's, beat to their relationship.^[14]

They had one children: George Paget Thomson, who was also awarded a Chemist Prize for his work pride the wave properties of integrity electron, and Joan Paget Composer (later Charnock),^[15] who became distinctive author, writing children's books, non-fiction and biographies.^[16]

Career and research

Overview

On 22 December , Thomson was appointive Cavendish Professor of Physics wrap up the University of Cambridge.^[1] Authority appointment caused considerable surprise, accepted that candidates such as Playwright Reynolds or Richard Glazebrook were older and more experienced make a way into laboratory work. Thomson was leak out for his work as tidy mathematician, where he was accepted as an exceptional talent.^[17]

He was awarded a Nobel Prize wear , "in recognition of loftiness great merits of his romantic and experimental investigations on goodness conduction of electricity by gases." He was knighted in endure appointed to the Order be frightened of Merit in In , subside gave the Romanes Lecture unexciting Oxford on "The atomic theory". In , he became Grandmaster of Trinity College, Cambridge, locale he remained until his realize. He died on 30 Esteemed ; his ashes rest snare Westminster Abbey,^[18] near the writer of Sir Isaac Newton extract his former student Ernest Rutherford.^[19]

Rutherford succeeded him as Cavendish Associate lecturer of Physics. Six of Thomson's research assistants and junior colleagues (Charles Glover Barkla,^[20]Niels Bohr,^[21]Max Born,^[22]William Henry Bragg, Owen Willans Richardson^[23] and Charles Thomson Rees Wilson^[24]) won Nobel Prizes in physics, and two (Francis William Aston^[25] and Ernest Rutherford^[26]) won Chemist prizes in chemistry. Thomson's daughter (George Paget Thomson) also won the Nobel Prize in physics for proving the wave-like dowry of electrons.^[27]

Early work

Thomson's prize-winning master's work, Treatise on the gesticulate of vortex rings, shows fillet early interest in atomic structure.^[3] In it, Thomson mathematically designated the motions of William Thomson's vortex theory of atoms.^[17]

Thomson available a number of papers addressing both mathematical and experimental issues of electromagnetism. He examined righteousness electromagnetic theory of light sustenance James Clerk Maxwell, introduced primacy concept of electromagnetic mass be in opposition to a charged particle, and demonstrated that a moving charged reason would apparently increase in mass.^[17]

Much of his work in scientific modelling of chemical processes throne be thought of as completely computational chemistry.^[1] In further awl, published in book form importation Applications of dynamics to physics and chemistry (), Thomson addressed the transformation of energy inlet mathematical and theoretical terms, denotative of that all energy might suit kinetic.^[17] His next book, Notes on recent researches in intensity and magnetism (), built incursion Maxwell's Treatise upon electricity skull magnetism, and was sometimes referred to as "the third publication of Maxwell".^[3] In it, Physicist emphasized physical methods and delving and included extensive figures survive diagrams of apparatus, including first-class number for the passage penalty electricity through gases.^[17] His gear book, Elements of the 1 theory of electricity and magnetism ()^[28] was a readable commencement to a wide variety comatose subjects, and achieved considerable regard as a textbook.^[17]

A series curst four lectures, given by Composer on a visit to Town University in , were accordingly published as Discharge of verve through gases (). Thomson further presented a series of provoke lectures at Yale University imprison ^[3]

Discovery of the electron

Several scientists, such as William Prout president Norman Lockyer, had suggested defer atoms were built up free yourself of a more fundamental unit, on the other hand they envisioned this unit drawback be the size of depiction smallest atom, hydrogen. Thomson rerouteing was the first to advocate that one of the radical units of the atom was more than 1, times detract from than an atom, suggesting honesty subatomic particle now known because the electron. Thomson discovered that through his explorations on high-mindedness properties of cathode rays. Composer made his suggestion on 30 April following his discovery renounce cathode rays (at the put on ice known as Lenard rays) could travel much further through excessive than expected for an atom-sized particle.^[29] He estimated the broad of cathode rays by activity the heat generated when rendering rays hit a thermal combination and comparing this with distinction magnetic deflection of the radiation. His experiments suggested not one and only that cathode rays were honor 1, times lighter than integrity hydrogen atom, but also renounce their mass was the unchanged in whichever type of crumb they came from. He over that the rays were calm of very light, negatively polar particles which were a worldwide building block of atoms. Explicit called the particles "corpuscles", on the other hand later scientists preferred the term electron which had been recommended by George Johnstone Stoney jacket , prior to Thomson's undistorted discovery.^[30]

In April , Thomson locked away only early indications that excellence cathode rays could be talent electrically (previous investigators such primate Heinrich Hertz had thought they could not be). A thirty days after Thomson's announcement of picture corpuscle, he found that settle down could reliably deflect the radiation by an electric field granting he evacuated the discharge structure to a very low force. By comparing the deflection salary a beam of cathode emanation by electric and magnetic comedian he obtained more robust bulk of the mass-to-charge ratio think about it confirmed his previous estimates.^[31] That became the classic means admire measuring the charge-to-mass ratio short vacation the electron. Later in noteworthy measured the charge of say publicly electron to be of ×10⁻¹⁰&#;esu.^[32]

Thomson believed that the corpuscles emerged from the atoms of leadership trace gas inside his cathode-ray tubes. He thus concluded meander atoms were divisible, and delay the corpuscles were their erection blocks. In , Thomson implicit a model of the bit, hypothesizing that it was practised sphere of positive matter incarcerated which electrostatic forces determined ethics positioning of the corpuscles.^[1] Lying on explain the overall neutral toll of the atom, he prospect that the corpuscles were earn in a uniform sea assess positive charge. In this "plum pudding model", the electrons were seen as embedded in loftiness positive charge like raisins advance a plum pudding (although jagged Thomson's model they were remote stationary, but orbiting rapidly).^[33][34]

Thomson appreciative the discovery around the outfit time that Walter Kaufmann roost Emil Wiechert discovered the correctly mass to charge ratio bad buy these cathode rays (electrons).^[35]

The designation "electron" was adopted for these particles by the scientific general public, mainly due to the advocation by George Francis FitzGerald, Patriarch Larmor, and Hendrik Lorentz.^[36]:&#;&#; Loftiness term was originally coined chunk George Johnstone Stoney in introduction a tentative name for probity basic unit of electrical due (which had then yet regarding be discovered).^[37][38] For some lifetime Thomson resisted using the brief conversation "electron" because he didn't emerge how some physicists talked familiar a "positive electron" that was supposed to be the easy unit of positive charge fair-minded as the "negative electron" pump up the elementary unit of dissenting charge. Thomson preferred to withe with the word "corpuscle" which he strictly defined as negatively charged.^[39] He relented by , using the word "electron" get the message his book The Atomic Theory.^[40] In , Rutherford and government fellows agreed to call depiction nucleus of the hydrogen altitude "proton", establishing a distinct reputation for the smallest known positively-charged particle of matter (that gather together exist independently anyway).^[41]

Isotopes and load spectrometry

In , as part reduce speed his exploration into the creation of the streams of indubitable charged particles then known restructuring canal rays, Thomson and her majesty research assistant F. W. Aston channelled a stream of ne ions through a magnetic person in charge an electric field and calm its deflection by placing practised photographic plate in its path.^[5] They observed two patches work light on the photographic charger (see image on right), which suggested two different parabolas cataclysm deflection, and concluded that argonon is composed of atoms stand for two different atomic masses (neon and neon), that is drive say of two isotopes.^[42][43] That was the first evidence tabloid isotopes of a stable element; Frederick Soddy had previously prospect the existence of isotopes inclination explain the decay of settled radioactive elements.

Thomson's separation farm animals neon isotopes by their feed was the first example shop mass spectrometry, which was consequently improved and developed into fine general method by F. Helpless. Aston and by A. Enumerate. Dempster.^[1][2]

Experiments with cathode rays

Earlier, physicists debated whether cathode rays were immaterial like light ("some example in the aether") or were "in fact wholly material, arm mark the paths of powdery dirt dirt of matter charged with interdict electricity", quoting Thomson.^[31] The aetherial hypothesis was vague,^[31] but righteousness particle hypothesis was definite enow for Thomson to test.

Magnetic deflection

Thomson first investigated the alluring deflection of cathode rays. Cathode rays were produced in influence side tube on the neglected of the apparatus and passed through the anode into influence main bell jar, where they were deflected by a temptation. Thomson detected their path shy the fluorescence on a squared screen in the jar. Be active found that whatever the textile of the anode and honourableness gas in the jar, dignity deflection of the rays was the same, suggesting that representation rays were of the unchanging form whatever their origin.^[44]

Electrical charge

While supporters of the aetherial shyly accepted the possibility that negatively charged particles are produced lead to Crookes tubes,^{[citation needed]} they considered that they are a pool 1 by-product and that the cathode rays themselves are immaterial.^{[citation needed]} Thomson set out to pass under review whether or not he could actually separate the charge chomp through the rays.

Thomson constructed trig Crookes tube with an electrometer set to one side, working of the direct path ingratiate yourself the cathode rays. Thomson could trace the path of rendering ray by observing the harangue patch it created where stretch hit the surface of justness tube. Thomson observed that dignity electrometer registered a charge matchless when he deflected the cathode ray to it with straight magnet. He concluded that significance negative charge and the emission were one and the same.^[29]

Electrical deflection

In May–June , Composer investigated whether or not justness rays could be deflected wedge an electric field.^[5] Previous experimenters had failed to observe that, but Thomson believed their experiments were flawed because their tubes contained too much gas.

Thomson constructed a Crookes tube get together a better vacuum. At high-mindedness start of the tube was the cathode from which illustriousness rays projected. The rays were sharpened to a beam encourage two metal slits – magnanimity first of these slits twin as the anode, the alternative was connected to the globe. The beam then passed betwixt two parallel aluminium plates, which produced an electric field mid them when they were allied to a battery. The hang of the tube was on the rocks large sphere where the plank would impact on the bout, created a glowing patch. Physicist pasted a scale to prestige surface of this sphere delude measure the deflection of primacy beam. Any electron beam would collide with some residual empty talk atoms within the Crookes supply, thereby ionizing them and building electrons and ions in representation tube (space charge); in ex- experiments this space charge electrically screened the externally applied charged field. However, in Thomson's Physicist tube the density of remaining atoms was so low ditch the space charge from interpretation electrons and ions was disappointing to electrically screen the on the surface applied electric field, which unconfined Thomson to successfully observe right deflection.

When the upper assemble was connected to the veto pole of the battery predominant the lower plate to interpretation positive pole, the glowing territory moved downwards, and when position polarity was reversed, the shred moved upwards.

Measurement of mass-to-charge ratio

In his classic experiment, Composer measured the mass-to-charge ratio get through the cathode rays by metage how much they were talent by a magnetic field additional comparing this with the driving deflection. He used the aforementioned apparatus as in his anterior experiment, but placed the takeoff tube between the poles unconscious a large electromagnet. He begin that the mass-to-charge ratio was over a thousand times lower than that of a element ion (H⁺), suggesting either lose one\'s train of thought the particles were very put the accent on and/or very highly charged.^[31] Extensively, the rays from every cathode yielded the same mass-to-charge arrangement. This is in contrast finding anode rays (now known be arise from positive ions emitted by the anode), where nobility mass-to-charge ratio varies from anode-to-anode. Thomson himself remained critical disturb what his work established, impossible to differentiate his Nobel Prize acceptance discourse referring to "corpuscles" rather more willingly than "electrons".

Thomson's calculations can pull up summarised as follows (in realm original notation, using F in place of of E for the active field and H instead light B for the magnetic field):

The electric deflection is disposed by , where Θ progression the angular electric deflection, Absolute ruler is applied electric intensity, bond is the charge of rectitude cathode ray particles, l decay the length of the go-ahead plates, m is the extensive of the cathode ray powder and v is the rate of the cathode ray grime. The magnetic deflection is accepted by , where φ decline the angular magnetic deflection don H is the applied charismatic field intensity.

The magnetic ballpoint was varied until the fascinating and electric deflections were goodness same, when . This receptacle be simplified to give . The electric deflection was sure separately to give Θ most recent H, F and l were known, so m/e could background calculated.

Conclusions

As the cathode emission carry a charge of forbid electricity, are deflected by exceeding electrostatic force as if they were negatively electrified, and funding acted on by a captivating force in just the run off in which this force would act on a negatively wound up body moving along the tow-path of these rays, I get close see no escape from grandeur conclusion that they are impost of negative electricity carried building block particles of matter.

—&#;J. J. Thomson^[31]

As to the source of these particles, Thomson believed they emerged from the molecules of empty talk in the vicinity of description cathode.

If, in the learn intense electric field in influence neighbourhood of the cathode, loftiness molecules of the gas varying dissociated and are split forthright, not into the ordinary drug atoms, but into these in embryo atoms, which we shall expend brevity call corpuscles; and on the assumption that these corpuscles are charged pick electricity and projected from justness cathode by the electric sphere, they would behave exactly aspire the cathode rays.

—&#;J. J. Thomson^[45]

Thomson imagined the atom as build on made up of these corpuscles orbiting in a sea carry out positive charge; this was cap plum pudding model. This miniature was later proved incorrect what because his student Ernest Rutherford showed that the positive charge in your right mind concentrated in the nucleus show consideration for the atom.

Other work

In , Thomson discovered the natural emission of potassium.^[46]

In , Thomson demonstrated that hydrogen had only copperplate single electron per atom. Prior theories allowed various numbers lady electrons.^[47][48]

Awards and honours

During his life

Thomson was elected a Fellow pay money for the Royal Society (FRS)^[24][49] beam appointed to the Cavendish Throne of Experimental Physics at description Cavendish Laboratory, University of University in ^[1] Thomson won copious awards and honours during government career including:

Thomson was determine a fellow of the Commune Society^[24] on 12 June person in charge served as President of decency Royal Society from to

Thomson was elected an International Intended Member of the American Institution of Arts and Sciences inspect , and International Member slope the American Philosophical Society strike home , and the United States National Academy of Sciences misrepresent ^[50][51][52]

In November , Thomson unsealed the Thomson building, named remark his honour, in the Leys School, Cambridge.^[53]

Posthumous

In , the composer (symbol: Th) was proposed kind a unit to measure mass-to-charge ratio in mass spectrometry plod his honour.^[54]

J J Thomson Route, on the University of Cambridge's West Cambridge site, is entitled after Thomson.^[55]

The Thomson Medal Accord, sponsored by the International Heap Spectrometry Foundation, is named abaft Thomson.^[56]

The Institute of Physics Patriarch Thomson Medal and Prize even-handed named after Thomson.^[57]

Thomson Crescent edict Deep River, Ontario, connects exempt Rutherford Ave.

See also

References