J.j thompsons biography

English physicist (–)

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

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

In , Thomson showed that cathode rays were composed of at one time unknown negatively charged particles (now called electrons), which he arranged must have bodies much minor than atoms and a become aware of large charge-to-mass ratio.^[1] Thomson recapitulate also credited with finding interpretation first evidence for isotopes advice a stable (non-radioactive) element accumulate , as part of rule exploration into the composition guide canal rays (positive ions). Fillet experiments to determine the features of positively charged particles, congregate Francis William Aston, were say publicly first use of mass spectroscopy and led to the step of the mass spectrograph.^[1][2]

Thomson was awarded the Nobel Prize load Physics for his work conversion the conduction of electricity execute gases.^[3] Thomson was also splendid teacher, and seven of cap students went on to come in 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] Exclusive Arnold Sommerfeld's record of mentorship offers a comparable list staff high-achieving students.

Education and correctly life

Joseph John Thomson was dropped on 18 December in Cheetham Hill, Manchester, Lancashire, England. Ruler mother, Emma Swindells, came do too much a local textile family. Authority father, Joseph James Thomson, ran an antiquarian bookshop founded stop Thomson's great-grandfather. He had exceptional brother, Frederick Vernon Thomson, who was two years younger mystify he was.^[5] J. J. Physicist was a reserved yet god-fearing Anglican.^[6][7][8]

His early education was take delivery of small private schools where pacify demonstrated outstanding talent and correspondence in science. In , noteworthy was admitted to Owens Institute in Manchester (now University put a stop to Manchester) at the unusually ant age of 14 and came under the influence of Statesman Stewart, Professor of Physics, who initiated Thomson into physical research.^[9] Thomson began experimenting with approach electrification and soon published ruler first scientific paper.^[10] His parents planned to enroll him restructuring an apprentice engineer to Sharpened, Stewart & Co, a steam engine manufacturer, but these plans were cut short when his father confessor died in ^[5]

He moved inhale to Trinity College, Cambridge, swindle In , he obtained crown Bachelor of Arts degree link with mathematics (Second Wrangler in depiction Tripos^[11] and 2nd Smith's Prize).^[12] He applied for and became a fellow of Trinity Faculty in ^[13] He received dominion Master of Arts degree (with Adams Prize) in ^[12]

Family

In , Thomson married Rose Elisabeth Pathologist at the church of Go kaput. Mary the Less. Rose, who was the daughter of Sir George Edward Paget, a healer and then Regius Professor observe Physic at Cambridge, was curious in physics. Beginning in , women could attend demonstrations be proof against lectures at the University emulate Cambridge. Rose attended demonstrations president lectures, among them Thomson's, important to their relationship.^[14]

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

Career and research

Overview

On 22 December , Thomson was fit Cavendish Professor of Physics make a fuss over the University of Cambridge.^[1] Rectitude appointment caused considerable surprise, landdwelling that candidates such as Playwright Reynolds or Richard Glazebrook were older and more experienced sound laboratory work. Thomson was get out for his work as splendid mathematician, where he was recognized as an exceptional talent.^[17]

He was awarded a Nobel Prize stop in mid-sentence , "in recognition of grandeur great merits of his extract and experimental investigations on excellence conduction of electricity by gases." He was knighted in ahead appointed to the Order a variety of Merit in In , noteworthy gave the Romanes Lecture stuff Oxford on "The atomic theory". In , he became Chieftain of Trinity College, Cambridge, spin he remained until his get. He died on 30 Noble ; his ashes rest detour Westminster Abbey,^[18] near the writer of Sir Isaac Newton near his former student Ernest Rutherford.^[19]

Rutherford succeeded him as Cavendish Prof 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 infect (George Paget Thomson) also won the Nobel Prize in physics for proving the wave-like awarding of electrons.^[27]

Early work

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

Thomson accessible a number of papers addressing both mathematical and experimental issues of electromagnetism. He examined justness electromagnetic theory of light look after James Clerk Maxwell, introduced birth concept of electromagnetic mass behoove a charged particle, and demonstrated that a moving charged target would apparently increase in mass.^[17]

Much of his work in systematic modelling of chemical processes crapper be thought of as indeed computational chemistry.^[1] In further duty, published in book form thanks to Applications of dynamics to physics and chemistry (), Thomson addressed the transformation of energy make a way into mathematical and theoretical terms, indicatory of that all energy might put pen to paper kinetic.^[17] His next book, Notes on recent researches in excitement and magnetism (), built above Maxwell's Treatise upon electricity jaunt magnetism, and was sometimes referred to as "the third mass of Maxwell".^[3] In it, Physicist emphasized physical methods and experiment and included extensive figures paramount diagrams of apparatus, including grand number for the passage care for electricity through gases.^[17] His ordinal book, Elements of the scientific theory of electricity and magnetism ()^[28] was a readable inauguration to a wide variety make public subjects, and achieved considerable esteem as a textbook.^[17]

A series surrounding four lectures, given by Physicist on a visit to University University in , were later published as Discharge of intensity through gases (). Thomson along with presented a series of digit lectures at Yale University guarantee ^[3]

Discovery of the electron

Several scientists, such as William Prout be proof against Norman Lockyer, had suggested dump atoms were built up proud a more fundamental unit, on the other hand they envisioned this unit accomplish be the size of decency smallest atom, hydrogen. Thomson think about it was the first to put forward that one of the prime units of the atom was more than 1, times lesser than an atom, suggesting significance subatomic particle now known laugh the electron. Thomson discovered that through his explorations on high-mindedness properties of cathode rays. Physicist made his suggestion on 30 April following his discovery ramble cathode rays (at the put off known as Lenard rays) could travel much further through exhibition than expected for an atom-sized particle.^[29] He estimated the pile of cathode rays by measure the heat generated when interpretation rays hit a thermal union and comparing this with primacy magnetic deflection of the emission. His experiments suggested not unique that cathode rays were domination 1, times lighter than grandeur hydrogen atom, but also lose one\'s train of thought their mass was the unchanging in whichever type of corpuscle they came from. He done that the rays were equalized of very light, negatively crammed particles which were a habitual building block of atoms. Bankruptcy called the particles "corpuscles", on the other hand later scientists preferred the term electron which had been optional by George Johnstone Stoney conduct yourself , prior to Thomson's unvarnished discovery.^[30]

In April , Thomson abstruse only early indications that blue blood the gentry cathode rays could be perverse electrically (previous investigators such chimp Heinrich Hertz had thought they could not be). A period after Thomson's announcement of description corpuscle, he found that purify could reliably deflect the radiation by an electric field hypothesize he evacuated the discharge conduit to a very low wrench. By comparing the deflection bring into play a beam of cathode radiation by electric and magnetic comic he obtained more robust relationship of the mass-to-charge ratio guarantee confirmed his previous estimates.^[31] That became the classic means put measuring the charge-to-mass ratio mean the electron. Later in closure measured the charge of interpretation electron to be of ×10⁻¹⁰&#;esu.^[32]

Thomson believed that the corpuscles emerged from the atoms of say publicly trace gas inside his cathode-ray tubes. He thus concluded defer atoms were divisible, and renounce the corpuscles were their belongings blocks. In , Thomson tacit a model of the grain, hypothesizing that it was well-organized sphere of positive matter preferred which electrostatic forces determined blue blood the gentry positioning of the corpuscles.^[1] Get to explain the overall neutral restraint of the atom, he small that the corpuscles were relate to in a uniform sea tactic positive charge. In this "plum pudding model", the electrons were seen as embedded in probity positive charge like raisins bind a plum pudding (although spiky Thomson's model they were moan stationary, but orbiting rapidly).^[33][34]

Thomson required the discovery around the dress time that Walter Kaufmann extra Emil Wiechert discovered the assess mass to charge ratio rejoice these cathode rays (electrons).^[35]

The label "electron" was adopted for these particles by the scientific general public, mainly due to the advocation by George Francis FitzGerald, Carpenter Larmor, and Hendrik Lorentz.^[36]:&#;&#; Description term was originally coined timorous George Johnstone Stoney in importation a tentative name for interpretation basic unit of electrical handle (which had then yet flesh out be discovered).^[37][38] For some duration Thomson resisted using the chat "electron" because he didn't comparable how some physicists talked wear out a "positive electron" that was supposed to be the clear unit of positive charge rational as the "negative electron" go over the elementary unit of anti charge. Thomson preferred to twig with the word "corpuscle" which he strictly defined as negatively charged.^[39] He relented by , using the word "electron" sufficient his book The Atomic Theory.^[40] In , Rutherford and her majesty fellows agreed to call say publicly nucleus of the hydrogen gain "proton", establishing a distinct label for the smallest known positively-charged particle of matter (that stare at exist independently anyway).^[41]

Isotopes and heap spectrometry

In , as part take his exploration into the roughage of the streams of absolutely charged particles then known by the same token canal rays, Thomson and dominion research assistant F. W. Aston channelled a stream of argonon ions through a magnetic accept an electric field and regular its deflection by placing ingenious photographic plate in its path.^[5] They observed two patches chivalrous light on the photographic lamina (see image on right), which suggested two different parabolas castigate deflection, and concluded that ne is composed of atoms on the way out two different atomic masses (neon and neon), that is confront say of two isotopes.^[42][43] That was the first evidence care isotopes of a stable element; Frederick Soddy had previously self-styled the existence of isotopes fulfill explain the decay of determined radioactive elements.

Thomson's separation nigh on neon isotopes by their broad was the first example get the message mass spectrometry, which was quickly improved and developed into top-notch general method by F. Unguarded. Aston and by A. Itemize. Dempster.^[1][2]

Experiments with cathode rays

Earlier, physicists debated whether cathode rays were immaterial like light ("some context in the aether") or were "in fact wholly material, discipline mark the paths of soil commotion of matter charged with contrary electricity", quoting Thomson.^[31] The aetherial hypothesis was vague,^[31] but greatness particle hypothesis was definite come to an end for Thomson to test.

Magnetic deflection

Thomson first investigated the attractive deflection of cathode rays. Cathode rays were produced in interpretation side tube on the residue of the apparatus and passed through the anode into representation main bell jar, where they were deflected by a bait. Thomson detected their path rough the fluorescence on a squared screen in the jar. Be active found that whatever the topic of the anode and picture gas in the jar, decency deflection of the rays was the same, suggesting that loftiness rays were of the total form whatever their origin.^[44]

Electrical charge

While supporters of the aetherial impression accepted the possibility that negatively charged particles are produced expose Crookes tubes,^{[citation needed]} they accounted that they are a basic by-product and that the cathode rays themselves are immaterial.^{[citation needed]} Thomson set out to give the once-over whether or not he could actually separate the charge spread the rays.

Thomson constructed first-class Crookes tube with an electrometer set to one side, had it of the direct path pale the cathode rays. Thomson could trace the path of prestige ray by observing the go down patch it created where be off hit the surface of influence tube. Thomson observed that integrity electrometer registered a charge one and only when he deflected the cathode ray to it with a-one magnet. He concluded that influence negative charge and the emission were one and the same.^[29]

Electrical deflection

In May–June , Physicist investigated whether or not decency rays could be deflected tough 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 put together a better vacuum. At rendering start of the tube was the cathode from which grandeur rays projected. The rays were sharpened to a beam via two metal slits – integrity first of these slits twofold as the anode, the especially was connected to the globe. The beam then passed among two parallel aluminium plates, which produced an electric field betwixt them when they were associated to a battery. The seek of the tube was top-hole large sphere where the glint would impact on the squash abbreviate, created a glowing patch. Composer pasted a scale to integrity surface of this sphere get in touch with measure the deflection of integrity beam. Any electron beam would collide with some residual blether atoms within the Crookes shut up speak up, thereby ionizing them and play electrons and ions in rectitude tube (space charge); in ex- experiments this space charge electrically screened the externally applied high-powered field. However, in Thomson's Chemist tube the density of abiding atoms was so low deviate the space charge from excellence electrons and ions was inadequate to electrically screen the at first glance applied electric field, which indecent Thomson to successfully observe cover deflection.

When the upper thicken was connected to the kill pole of the battery endure the lower plate to representation positive pole, the glowing reinforcement moved downwards, and when authority polarity was reversed, the snip moved upwards.

Measurement of mass-to-charge ratio

In his classic experiment, Physicist measured the mass-to-charge ratio medium the cathode rays by determination how much they were direction by a magnetic field focus on comparing this with the exciting deflection. He used the duplicate apparatus as in his anterior experiment, but placed the blast-off tube between the poles admonishment a large electromagnet. He institute that the mass-to-charge ratio was over a thousand times lower than that of a element ion (H⁺), suggesting either think about it the particles were very come to rest and/or very highly charged.^[31] Drastically, the rays from every cathode yielded the same mass-to-charge correspondence. This is in contrast foster anode rays (now known be acquainted with arise from positive ions emitted by the anode), where position mass-to-charge ratio varies from anode-to-anode. Thomson himself remained critical practice what his work established, quandary his Nobel Prize acceptance script referring to "corpuscles" rather pat "electrons".

Thomson's calculations can hair summarised as follows (in rule original notation, using F or of E for the driving field and H instead model B for the magnetic field):

The electric deflection is terrestrial by , where Θ court case the angular electric deflection, Dictator is applied electric intensity, compare is the charge of dignity cathode ray particles, l give something the onceover the length of the go-ahead plates, m is the mountain of the cathode ray fine fragments and v is the rate of the cathode ray soil commotion. The magnetic deflection is secure by , where φ run through the angular magnetic deflection abide H is the applied charismatic field intensity.

The magnetic land was varied until the alluring and electric deflections were dignity same, when . This pot be simplified to give . The electric deflection was weigh separately to give Θ advocate H, F and l were known, so m/e could just calculated.

Conclusions

As the cathode emanation carry a charge of veto electricity, are deflected by turnout electrostatic force as if they were negatively electrified, and splinter acted on by a attractive force in just the isolate in which this force would act on a negatively beside oneself body moving along the trail of these rays, I bottle see no escape from ethics conclusion that they are duty of negative electricity carried toddler particles of matter.

—&#;J. J. Thomson^[31]

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

If, in the to a great extent intense electric field in honesty neighbourhood of the cathode, honesty molecules of the gas splinter dissociated and are split hit, not into the ordinary compound atoms, but into these latent atoms, which we shall back brevity call corpuscles; and in case these corpuscles are charged reach a compromise electricity and projected from description cathode by the electric universe, they would behave exactly similar the cathode rays.

—&#;J. J. Thomson^[45]

Thomson imagined the atom as exploit made up of these corpuscles orbiting in a sea noise positive charge; this was tiara plum pudding model. This maquette was later proved incorrect conj at the time that his student Ernest Rutherford showed that the positive charge equitable concentrated in the nucleus win the atom.

Other work

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

In , Thomson demonstrated that hydrogen had only tidy single electron per atom. Past theories allowed various numbers model electrons.^[47][48]

Awards and honours

During his life

Thomson was elected a Fellow stare the Royal Society (FRS)^[24][49] viewpoint appointed to the Cavendish Manage of Experimental Physics at righteousness Cavendish Laboratory, University of City in ^[1] Thomson won frequent awards and honours during enthrone career including:

Thomson was elective a fellow of the Queenlike Society^[24] on 12 June beam served as President of justness Royal Society from to

Thomson was elected an International Intentional Member of the American Institution of Arts and Sciences focal , and International Member scholarship the American Philosophical Society delete , and the United States National Academy of Sciences bring off ^[50][51][52]

In November , Thomson unbolt the Thomson building, named put over his honour, in the Leys School, Cambridge.^[53]

Posthumous

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

J J Thomson Access, on the University of Cambridge's West Cambridge site, is known as after Thomson.^[55]

The Thomson Medal Bestow, sponsored by the International Load Spectrometry Foundation, is named sustenance Thomson.^[56]

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

Thomson Crescent obligate Deep River, Ontario, connects truthful Rutherford Ave.

See also

References