Post on 03-Apr-2018
7/29/2019 P3 - Homework Week 11 - Questions
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P3-Homeworkweek11[RevisionProblems]
Youmayusethefollowinginformation:
Chargeofproton=1.60210-19CChargeofelectron=-1.60210-19C
Massofproton=1.67310-27kgMassofneutron=1.67510-27kgPlancksconstant=6.6310-34m2kgs-1
1)a)Explainwhatismeantbyanisotope
b)TheincompletetablebelowshowsinformationfortwoisotopesofUranium
Numberof
protons
Numberof
neutrons
Specificcharge
ofnucleus/.FirstIsotope 92 143
SecondIsotope 3.7107
Copythetableinyouranswersheetand
i)writedowntheunitforthespecificchargeintheheadingofthelastcolumnofthetable.
ii)intheabovetable,writedownthenumberofprotonsinthesecond
isotope.Writedownclearlyhowyoucalculatedthisnumber. iii)calculatethespecificchargeofthefirstisotopeandwritethisinthe
table.Writedownclearlyhowyoucalculatedthisnumber.
iv)calculatethenumberofneutronsinthesecondisotopeandputthisnumberinthetable.
2)Whenmonochromaticlightshinesuponametalsurface,electronsareemitted
fromthesurfaceasdescribedbythephotoelectriceffect. a)Statewhatismeantbythresholdfrequencyinthecontextofthe
photoelectriceffect.
b)Stateanddescribetheeffectontheemittedelectronsif i)thefrequencyofthelightisincreased.
ii)theintensityofthelightisincreased.
c)Thethresholdfrequencyoflithiumis5.51014
Hz.Calculatetheworkfunctionoflithium.
d)Whatisthemaximumkineticenergyoftheemittedelectronswhenlightoffrequency6.21014Hzisincidentonthesurfaceofasampleoflithium?
3)Awirewithcross-sectionaldiameterof2mmismadefromcopper.Copperhas1.101029freeelectronspermetrecubed.Whatisthevalueofthecurrent
flowingthroughthewirewhenthedriftspeedofelectronsis0.093mms-1?
Answers:
1)b)ii)92iii)3.65107iv)1462)c)3.6510-19Jd)4.610-20J
3)5.15A
7/29/2019 P3 - Homework Week 11 - Questions
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