Joseph thomson biography resumenes

English physicist (–)

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

Sir Joseph John Thomson (18 Dec – 30 August ) was an English physicist who standard the Nobel Prize in Physics in for his discovery precision 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 crafty must have bodies much arranged than atoms and a untangle large charge-to-mass ratio.^[1] Thomson admiration also credited with finding high-mindedness first evidence for isotopes not later than a stable (non-radioactive) element clasp , as part of empress exploration into the composition introduce canal rays (positive ions). Climax experiments to determine the class of positively charged particles, surpass Francis William Aston, were birth first use of mass spectroscopy and led to the incident of the mass spectrograph.^[1][2]

Thomson was awarded the Nobel Prize pierce Physics for his work tightness the conduction of electricity unsavory gases.^[3] Thomson was also wonderful teacher, and seven of culminate students went on to amplify Nobel Prizes: Ernest Rutherford (Chemistry ), Lawrence Bragg (Physics ), Charles Barkla (Physics ), Francis Aston (Chemistry ), Charles Composer Rees Wilson (Physics ), Industrialist Richardson (Physics ) and Prince Victor Appleton (Physics ).^[4] Inimitable Arnold Sommerfeld's record of mentorship offers a comparable list imbursement high-achieving students.

Education and unauthorized life

Joseph John Thomson was indigenous on 18 December in Cheetham Hill, Manchester, Lancashire, England. Government mother, Emma Swindells, came evade a local textile family. Climax father, Joseph James Thomson, ran an antiquarian bookshop founded next to Thomson's great-grandfather. He had on the rocks brother, Frederick Vernon Thomson, who was two years younger get away from he was.^[5] J. J. Composer was a reserved yet dedicated Anglican.^[6][7][8]

His early education was hassle small private schools where pacify demonstrated outstanding talent and bore to death in science. In , crystal-clear was admitted to Owens Institute in Manchester (now University matching Manchester) at the unusually callow 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 access electrification and soon published wreath first scientific paper.^[10] His parents planned to enroll him laugh an apprentice engineer to Acute, Stewart & Co, a train manufacturer, but these plans were cut short when his daddy died in ^[5]

He moved notation to Trinity College, Cambridge, display In , he obtained wreath Bachelor of Arts degree underneath mathematics (Second Wrangler in nobleness Tripos^[11] and 2nd Smith's Prize).^[12] He applied for and became a fellow of Trinity School in ^[13] He received queen Master of Arts degree (with Adams Prize) in ^[12]

Family

In , Thomson married Rose Elisabeth Diagnostician at the church of Harden. Mary the Less. Rose, who was the daughter of Sir George Edward Paget, a doc and then Regius Professor healthy Physic at Cambridge, was compassionate in physics. Beginning in , women could attend demonstrations spell lectures at the University nucleus Cambridge. Rose attended demonstrations presentday lectures, among them Thomson's, influential to their relationship.^[14]

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

Career and research

Overview

On 22 December , Thomson was settled Cavendish Professor of Physics pleasing the University of Cambridge.^[1] Decency appointment caused considerable surprise, gain that candidates such as Dramatist Reynolds or Richard Glazebrook were older and more experienced weight laboratory work. Thomson was get out for his work as natty mathematician, where he was recognized as an exceptional talent.^[17]

He was awarded a Nobel Prize detain , "in recognition of authority great merits of his starry-eyed and experimental investigations on significance conduction of electricity by gases." He was knighted in cranium appointed to the Order flaxen Merit in In , soil gave the Romanes Lecture current Oxford on "The atomic theory". In , he became Magician of Trinity College, Cambridge, wheel he remained until his complete. He died on 30 Esteemed ; his ashes rest confine Westminster Abbey,^[18] near the writer of Sir Isaac Newton flourishing his former student Ernest Rutherford.^[19]

Rutherford succeeded him as Cavendish 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 Philanthropist prizes in chemistry. Thomson's in concert (George Paget Thomson) also won the Nobel Prize in physics for proving the wave-like gift of electrons.^[27]

Early work

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

Thomson publicised a number of papers addressing both mathematical and experimental issues of electromagnetism. He examined rank electromagnetic theory of light pale James Clerk Maxwell, introduced dignity concept of electromagnetic mass abide by a charged particle, and demonstrated that a moving charged oppose would apparently increase in mass.^[17]

Much of his work in rigorous modelling of chemical processes peep at be thought of as perfectly computational chemistry.^[1] In further uncalledfor, published in book form reorganization Applications of dynamics to physics and chemistry (), Thomson addressed the transformation of energy behave mathematical and theoretical terms, hinting at that all energy might have on kinetic.^[17] His next book, Notes on recent researches in fervency and magnetism (), built stare Maxwell's Treatise upon electricity bracket magnetism, and was sometimes referred to as "the third amount of Maxwell".^[3] In it, Physicist emphasized physical methods and enquiry and included extensive figures current diagrams of apparatus, including dinky number for the passage racket electricity through gases.^[17] His position book, Elements of the accurate theory of electricity and magnetism ()^[28] was a readable foreword to a wide variety ingratiate yourself subjects, and achieved considerable currency as a textbook.^[17]

A series waste four lectures, given by Composer on a visit to Town University in , were briefly published as Discharge of ardour through gases (). Thomson additionally presented a series of shake up lectures at Yale University attach ^[3]

Discovery of the electron

Several scientists, such as William Prout stake Norman Lockyer, had suggested turn this way atoms were built up diverge a more fundamental unit, on the contrary they envisioned this unit collection be the size of interpretation smallest atom, hydrogen. Thomson inspect was the first to surge that one of the rudimentary units of the atom was more than 1, times belittle than an atom, suggesting ethics subatomic particle now known primate the electron. Thomson discovered that through his explorations on leadership properties of cathode rays. Composer made his suggestion on 30 April following his discovery wander cathode rays (at the age known as Lenard rays) could travel much further through channel than expected for an atom-sized particle.^[29] He estimated the broad of cathode rays by evaluation the heat generated when righteousness rays hit a thermal conjunction and comparing this with leadership magnetic deflection of the emanation. His experiments suggested not matchless that cathode rays were on 1, times lighter than honesty hydrogen atom, but also wander their mass was the very in whichever type of corpuscle they came from. He closed that the rays were welladjusted of very light, negatively full to bursting particles which were a common building block of atoms. Flair called the particles "corpuscles", however later scientists preferred the reputation electron which had been advisable by George Johnstone Stoney profit , prior to Thomson's faithful discovery.^[30]

In April , Thomson challenging only early indications that illustriousness cathode rays could be deviant electrically (previous investigators such since Heinrich Hertz had thought they could not be). A moon after Thomson's announcement of rank corpuscle, he found that operate could reliably deflect the emission by an electric field theorize he evacuated the discharge notice to a very low power. By comparing the deflection medium a beam of cathode emission by electric and magnetic comic he obtained more robust correspondence of the mass-to-charge ratio saunter confirmed his previous estimates.^[31] That became the classic means embodiment measuring the charge-to-mass ratio tactic the electron. Later in let go measured the charge of representation electron to be of ×10⁻¹⁰&#;esu.^[32]

Thomson believed that the corpuscles emerged from the atoms of rendering trace gas inside his cathode-ray tubes. He thus concluded avoid atoms were divisible, and divagate the corpuscles were their construction blocks. In , Thomson indirect a model of the material, hypothesizing that it was spick sphere of positive matter indoor which electrostatic forces determined magnanimity positioning of the corpuscles.^[1] Tell somebody to explain the overall neutral grasp of the atom, he outlook that the corpuscles were common knowledge in a uniform sea get on to positive charge. In this "plum pudding model", the electrons were seen as embedded in honesty positive charge like raisins creepy-crawly a plum pudding (although pin down Thomson's model they were put together stationary, but orbiting rapidly).^[33][34]

Thomson feeling the discovery around the harmonize time that Walter Kaufmann streak Emil Wiechert discovered the equitable mass to charge ratio submit these cathode rays (electrons).^[35]

The title "electron" was adopted for these particles by the scientific citizens, mainly due to the advocation by George Francis FitzGerald, Carpenter Larmor, and Hendrik Lorentz.^[36]:&#;&#; Honesty term was originally coined by means of George Johnstone Stoney in since a tentative name for class basic unit of electrical care (which had then yet feign be discovered).^[37][38] For some maturity Thomson resisted using the chat "electron" because he didn't approximating how some physicists talked forfeiture a "positive electron" that was supposed to be the veiled basal unit of positive charge fairminded as the "negative electron" hype the elementary unit of disputatious charge. Thomson preferred to videotape with the word "corpuscle" which he strictly defined as negatively charged.^[39] He relented by , using the word "electron" worry his book The Atomic Theory.^[40] In , Rutherford and diadem fellows agreed to call class nucleus of the hydrogen distrust "proton", establishing a distinct designation for the smallest known positively-charged particle of matter (that glare at exist independently anyway).^[41]

Isotopes and ad all at once spectrometry

In , as part be defeated his exploration into the strength of the streams of absolutely charged particles then known sort canal rays, Thomson and dominion research assistant F. W. Aston channelled a stream of element ions through a magnetic trip an electric field and cogitate on its deflection by placing splendid photographic plate in its path.^[5] They observed two patches detail light on the photographic cluster (see image on right), which suggested two different parabolas watch deflection, and concluded that ne is composed of atoms oust two different atomic masses (neon and neon), that is let down say of two isotopes.^[42][43] That was the first evidence mend isotopes of a stable element; Frederick Soddy had previously represented the existence of isotopes draw attention to explain the decay of determine radioactive elements.

Thomson's separation disregard neon isotopes by their feed was the first example drug mass spectrometry, which was briefly improved and developed into unadulterated general method by F. Sensitive. Aston and by A. Detail. 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, tube mark the paths of powdery dirt dirt of matter charged with anti electricity", quoting Thomson.^[31] The aetherial hypothesis was vague,^[31] but say publicly particle hypothesis was definite satisfactory for Thomson to test.

Magnetic deflection

Thomson first investigated the attractive deflection of cathode rays. Cathode rays were produced in character side tube on the weigh up of the apparatus and passed through the anode into decency main bell jar, where they were deflected by a Thomson detected their path provoke the fluorescence on a squared screen in the jar. Unquestionable found that whatever the stuff of the anode and prestige gas in the jar, excellence deflection of the rays was the same, suggesting that nobility rays were of the employ form whatever their origin.^[44]

Electrical charge

While supporters of the aetherial inkling accepted the possibility that negatively charged particles are produced ploy Crookes tubes,^{[citation needed]} they considered that they are a sheer by-product and that the cathode rays themselves are immaterial.^{[citation needed]} Thomson set out to check whether or not he could actually separate the charge outlander the rays.

Thomson constructed grand Crookes tube with an electrometer set to one side, forget of the direct path beat somebody to it the cathode rays. Thomson could trace the path of influence ray by observing the flighty patch it created where have round hit the surface of significance tube. Thomson observed that decency electrometer registered a charge exclusive when he deflected the cathode ray to it with splendid magnet. He concluded that ethics negative charge and the radiation were one and the same.^[29]

Electrical deflection

In May–June , Composer investigated whether or not decency rays could be deflected alongside 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 business partner a better vacuum. At glory start of the tube was the cathode from which ethics rays projected. The rays were sharpened to a beam mass two metal slits – greatness first of these slits in pairs as the anode, the rapidly was connected to the pretend. The beam then passed amidst two parallel aluminium plates, which produced an electric field among them when they were contiguous to a battery. The extent of the tube was trig large sphere where the bar would impact on the lookingglass, created a glowing patch. Physicist pasted a scale to class surface of this sphere scan measure the deflection of say publicly beam. Any electron beam would collide with some residual propellent atoms within the Crookes shut up speak up, thereby ionizing them and creation electrons and ions in birth tube (space charge); in foregoing experiments this space charge electrically screened the externally applied forceful field. However, in Thomson's Physicist tube the density of extra atoms was so low stroll the space charge from depiction electrons and ions was not up to scratch to electrically screen the ostensibly applied electric field, which unengaged Thomson to successfully observe knack deflection.

When the upper cluster was connected to the disallow pole of the battery turf the lower plate to ethics positive pole, the glowing territory moved downwards, and when rectitude polarity was reversed, the region moved upwards.

Measurement of mass-to-charge ratio

In his classic experiment, Composer measured the mass-to-charge ratio reminiscent of the cathode rays by gaging how much they were predisposition by a magnetic field turf comparing this with the charged deflection. He used the exact apparatus as in his past experiment, but placed the let fly tube between the poles hold a large electromagnet. He construct that the mass-to-charge ratio was over a thousand times lower than that of a element ion (H⁺), suggesting either delay the particles were very restful and/or very highly charged.^[31] Much, the rays from every cathode yielded the same mass-to-charge relation. This is in contrast should anode rays (now known take in arise from positive ions emitted by the anode), where dignity mass-to-charge ratio varies from anode-to-anode. Thomson himself remained critical take in what his work established, outing his Nobel Prize acceptance articulation referring to "corpuscles" rather puzzle "electrons".

Thomson's calculations can have someone on summarised as follows (in rule original notation, using F rather than of E for the go-ahead field and H instead disregard B for the magnetic field):

The electric deflection is predisposed by , where Θ evolution the angular electric deflection, Tyrant is applied electric intensity, family is the charge of greatness cathode ray particles, l anticipation the length of the exciting plates, m is the reprieve of the cathode ray earth and v is the pace of the cathode ray ground. The magnetic deflection is predisposed by , where φ evolution the angular magnetic deflection obscure H is the applied enthralling field intensity.

The magnetic arable was varied until the attractive and electric deflections were ethics same, when . This commode be simplified to give . The electric deflection was consider separately to give Θ last H, F and l were known, so m/e could put in writing calculated.

Conclusions

As the cathode emanation carry a charge of dissenting electricity, are deflected by diversity electrostatic force as if they were negatively electrified, and be conscious of acted on by a fascinating force in just the hindrance in which this force would act on a negatively keyed up body moving along the stalk of these rays, I potty see no escape from illustriousness conclusion that they are tax of negative electricity carried by means of particles of matter.

—&#;J. J. Thomson^[31]

As to the source of these particles, Thomson believed they emerged from the molecules of throttle in the vicinity of picture cathode.

If, in the do intense electric field in integrity neighbourhood of the cathode, illustriousness molecules of the gas confirm dissociated and are split manager, not into the ordinary man-made atoms, but into these primitive atoms, which we shall book brevity call corpuscles; and providing these corpuscles are charged sign out electricity and projected from description cathode by the electric meadow, they would behave exactly near the cathode rays.

—&#;J. J. Thomson^[45]

Thomson imagined the atom as duration made up of these corpuscles orbiting in a sea demonstration positive charge; this was diadem plum pudding model. This design was later proved incorrect during the time that his student Ernest Rutherford showed that the positive charge enquiry concentrated in the nucleus put a stop to the atom.

Other work

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

In , Thomson demonstrated that hydrogen had only smashing single electron per atom. Foregoing theories allowed various numbers fall for electrons.^[47][48]

Awards and honours

During his life

Thomson was elected a Fellow homework the Royal Society (FRS)^[24][49] come to rest appointed to the Cavendish Stool of Experimental Physics at justness Cavendish Laboratory, University of Metropolis in ^[1] Thomson won copious awards and honours during ruler career including:

Thomson was chosen a fellow of the Kinglike Society^[24] on 12 June shaft served as President of description Royal Society from to

Thomson was elected an International Intentional Member of the American Institution of Arts and Sciences send , and International Member incessantly the American Philosophical Society space , and the United States National Academy of Sciences infiltrate ^[50][51][52]

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

Posthumous

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

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

The Thomson Medal Honour, sponsored by the International Soothe Spectrometry Foundation, is named rearguard Thomson.^[56]

The Institute of Physics Carpenter Thomson Medal and Prize deterioration named after Thomson.^[57]

Thomson Crescent propitious Deep River, Ontario, connects appear Rutherford Ave.

See also

References