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Paper 26

ACT June 2018

Form A11 · Reading Test · 40 questions

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Paper 26 · ACT June 2018 · Form A11 · Reading Test

0 chaTge, gain'.ng oi" losing an electi'on (qi s he saw it) durinG th= measureinent. Millik<ili may Lfllso have jud•ed some droplets to be too small or too l£Trige to io yield reliable data. Good,stein SLlyS. If they were too large, they would fcl11 too rapidly to be ieliably obs-ri'ed. Too %mi£11: and llieii fic11 (and thiis the chai.ge resuli". ￿OUld be affectad by rcindom collisions with ali mole.=Lles. Goodstein interprets the italicised stateinenl 75 as all aisertion that there were oiily fifty-eight 'com- plete ciough, sets of dtlta. But Goodstein undoes his defence by stating that ip_ order io make the 'too large, or 'too small, distiiic- lian. all ihe data would need to hcive been takeii iii the 80 fir.)t place. Millikan certainly did not convince his peers Ktraig.It aw'ay. The arguments with Elii'enliaft ILimbled on lono vnouoh for Millik&n',s Nobel Prize to be dcla):ed lor three years-it eventLially came in 1923. But here's the poillt.. Millikan Wcls l-ight IL boLlt the elevtron and its charge. Few IciboiaLoi"ies rnanaged to replicate Ehrcnh£ift's resiilts, but students Iiow I'eplicate Millikall'o results all Acioss the world. No oiie now belie￿eS that Ihe fundament£il unit of chcirge is anything 90 0:.her than Millikan's e. Millik<in's idea Wi1S siinple. A droplet o. water that hTrc d been given an electric chlc I'ge would be atLracted to a metal plate which cariied an opposite c.iarue. He ari'tinged his appar<ltus so that the electrical attraction 10 PLilled the droplet LIP, wliile giavity pulled :t dowv.. This g2c ve hitn a way to measure e. First he ￿'OUld find th- m£lb.s of the (Iroplet, Tlien he would measure the voltag- needed for the attractioii to the metal plate to cancel out the downwaid piill of gi'2¢ Vlty, From ihoEe tivo pieceb of 15 inforrnation he coiild get a measure of the charg- on the droplet. The experiment W£iS fai" from simple to cartv oui, howevei". Finding that the water drop'"ets tended t evapoi.ate befoie ny rne£isiirements could be made: 20 Millikcln set to Lhc task ol trying Ihe Rame trick ivitF. oil droplets. In 1910, at the age of foity-two. he finallv pub- lisliecl a V<llue for e. It W1( s mecint to be FIIS bareer- defining publication. Eventually, it was-but Millikar. 25 Still had yeiors of difficuli and dirty, work ahead of him. The Austrian physicist Felix Ehrenhaft refuted Millikan's results with a similar set of ekperimell ts that seemed to show that electi.ical charge cdn.be infinil=l) small. There is no tundamental, minimuin iinit of SO ch¢qrge, Ehrenhaft gaid; theie is no 'electron' The series of experitnents thc despci'ate Millikan then performed wci'e to cast a lasting shadow oveI hiE fc-er,lific integrity, ALcorcling to biologist Richard Lewont'n. fvlil;'ikan 35 'went out of his way to hi(le the exiitellce of in.onve- nient d<lta'. David Goodstein, a phvbics prof=ssor, sas-s Millikan 'certainly did not commit scientific fraud. So whei"e does ihe ti'uth lie? 85 To get his Nobel Prize, Millikan hc2d to play h2cid aid fdsi Wlth what we Inight call 'accepied pi'actice,. The debate hangs on a phrase in Millikan's 191- 40 P¢1per reFLlting Ehrenhaft 12nd showing that everv ￿e2- sureiiient of electric charge gives a value of e or inte- ger mLiltiple OF e. In his 1913 papei-. Mi likcir: say.E that his claL£q tcible 'cuntains ll rot711)lete .s1{.Fnrwry ol tkie p'esLilts obtaiiied on cill Gf Ille 58 d,.rferent draps UPGn 45 Trp,hicli complete series oj. obseripalions were ￿.a￿le. The stELtement is writLeii in itcilics, as if lo give il spec.al weight. Tlie notebDoks foi" (he 1913 paper show that Millikoc n £Trcliially took datci on 100 oil droplets. Did MillikqL n cheri'y-pick the diit¢q in Order to knonfirn his 50 origiiial i"esiilt and crLish Elii"enhaft underfo8t-: He certainly ha(1 n]otive. In MilliLan's 1910 p.Iper he ha(1 Incide Lhe 'iiiisLake' of full disclo)ure with sta-e-

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