modul f t 5 keradioaktifan 5 radioactivity · based on the graph above, determine the half-life of...

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MODUL • Fizik TINGKATAN 5

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KeradioaktifanRadioactivity5

• Menghuraikankomposisinukleusatomdalamsebutanprotondanneutron.Describe the composition of the nucleus of an atom in terms of protons and neutrons.

• Mendefinisikannomborproton(Z)dannombornukleon(A)./Define proton number (Z) and nucleon number (A).• Menerangkanistilahnuklid./Explain the term nuclide.• Menggunakannotasinuklid

A

ZX/Use the nuclide notation

A

ZX

• Mendefinisikanistilahisotop./Define the term isotope.

5.1 Memahami nukleus atom / Understanding the nucleus of an atom

• Menyatakanmaknaradioaktif./State what radioactivity is.• Menamakanpengesansinaranradioaktif./Name common detectors for radioactive emissions.• Membeza-bandingkan3jenissinaranradioaktifdariaspekkesemulajadiannya.

Compare the three kinds of radioactive emissions in terms of their nature.• Menerangkanreputanradioaktif./Explain what radioactive decay is.• Menggunakanpersamaanuntukmenggambarkanperubahankomposisinukluesapabilazarahdipancarkan.

Use equations to represent changes in the composition of the nucleus when particles are emitted.• Menerangkansetengahhayat./Explain half-life.• Menentukansetengahhayatdarisuatugrafreputan./Determine half-life from a decay curve.• Menyelesaikanmasalahberkaitansetengahhayat./Solve problems involving half-life.

5.2 Menganalisis reputan radioaktif / Analysing radioactive decay

• Mendefinisikanradioisotop./Define radioisotopes.• Menamakancontohradioisotop./Name examples of radioisotopes.• Menghuraikanaplikasiradioisotop./Describe applications of radioisotopes.

5.3 Memahami kegunaan radioisotop / Understanding the uses of radioisotopes

• Mendefinisikanunitjisimatom(u.j.a.)./Define atomic mass unit (a.m.u.).• Menghuraikanpelakurannuklear./Describe nuclear fission.• Memberikancontohpelakurannuklear./Give examples of nuclear fission.• Menghuraikantindakbalasberantai./Describe chain reactions.• Menghuraikanpelakurannuklear./Describe nuclear fusion.• Memberikancontohpelakurannuklear./Give examples of nuclear fusion.• Menghubungkaitkanpelepasantenagatindakbalasnukleardenganperubahanjisimberdasarkanpersamaan• E=mc2./Relate the release of energy in a nuclear reaction with change of mass according to the equation E = mc2.• Menghuraikanpenjanaanelektrikdaripelakurannuklear./Describe the generation of electricity from nuclear fission.• Memberialasankuatuntukpenggunaanpelakurannukleardalampenjanaanelektrik.

Justify the use of nuclear fission in the generation of electricity.• Menyelesaikanmasalahberkaitantenaganuklear./Solve problems involving nuclear energy.

5.4 Memahami tenaga nuklear / Understanding nuclear energy

05-Physic F5 2015 (FSY5p).indd 188 10/15/15 3:14 PM

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1 Jirimterdiridaripadazarahkecilyangdinamakan atom .

Matter is made up of very small particles called atoms .

2 Setiapatommempunyaiterasyangsangatkecildansangattumpatyangdinamakan nukleus dan

elektron mengelilinginya.

Each atom has a very small and very dense core called nucleus and electrons move in orbits around the nucleus.

3 Kebanyakan jisim atomterdapatdidalamnukleus.

Most of the mass of atom is contained in the nucleus.

4 Nukleusterdiridaripada proton danneutron.

A nucleus consists of a number of protons and neutrons.

5 Protondanneutronjugadikenalisebagai nukleon .

Protons and neutrons also known as nucleons .

6 Protonbercas positif .

A proton has a positive charge.

7 Neutronialahzarahyang tidakbercas yangmempunyai jisimyangsama sepertiproton.

A neutron is an uncharged particle of the same mass as the proton.

TerminologiTerminology

PeneranganExplanation

Nomborproton,ZProton number, Z

Didefinisikansebagai bilanganprotondalamnukleus .

Is defined as the number of protons in a nucleus .

Nombornukleon,ANucleon number, A

Jumlahbilanganprotondanneutrondalamnukleus .

Is the total number of protons and neutrons in a nucleus .

NuklidNuclide

Nuklid ialah struktur atom tertentu yang mempunyai nombor nukleon dan nombor protontersendiri.A nuclide is an atom of a particular structure, having its own particular nucleon number and proton number.A

ZX

IsotopIsotope

Isotopialahstrukturatomyangmempunyainombor protonyangsama tetapi

nombor nukleon yangberbeza.

Isotopes are atoms which have the same proton number but different nucleon numbers.

• Menghuraikankesanburukbahanradioaktif./Describe the negative effects of radioactive substances.• Menghuraikanlangkah-langkahkeselamatanyangdiperlukandalampengendalianbahanradioaktif.

Describe safety precautions needed in the handling of radioactive substances.• Menghuraikanpengurusanbuanganradioaktif./Describe the management of radioactive waste.

5.5 Kesedaran kepentingan pengurusan baik terhadap bahan radioaktifRealising the importance of proper management of radioactive substances

Memahami Nukleus Bagi Atom Understanding the Nucleus of An Atom

5.1




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1 ContohbaginuklidX/Example of nuclide X.(a) 40

10X(i) NomborprotonbagiXialah 10 .

The proton number of X is 10 .

(ii) NombornukleonbagiXialah 40 .

The nucleon number of X is 40 .

(iii) BilanganneutrondalamnukleusXialah 40–10=30 .

The number of neutrons in X nucleus is 40 – 10 = 30 .

(b) 12

6C(i) NomborprotonbagiatomCialah 6 .

The proton number of C is 6 .

(ii) NombornukleonbagiatomCialah 12 .

The nucleon number of C is 12 .

(iii) BilanganneutrondalamatomCialah 6 .

The number of neutrons in C nucleus is 6 .

(c) 84

36Kr(i) Berapakahbilanganneutrondalamnukleusatomkripton?

What is the number of neutrons in the nucleus of krypton?

84–36=48

(ii) Nukleusbagikripton lainmempunyaiduaneutronyangberlebihan.TuliskansimboldalambentukA

ZXbagiatomkriptonini. Another nuclide of krypton has two extra neutrons. Write the nuclide notation for this nuclide.

Bilanganneutron=48+2=50

Nomborprotonkekalsamadengan36memandangkanianyaelemenyangsama

Nombornukleon=36+50=86

Simbolbagiisotopkriptoniniialah86

36Kr Number of neutrons = 48 + 2 = 50

The proton number remains at 36 since it is the same element

Nucleon number = 36 + 50 = 86

Symbol for this isotope of krypton is

86

36Kr

2 Isotopsuatuunsurmempunyaibilangan proton danbilangan elektron yangsama.

Isotopes of an element contain the same number of protons and the same number of electrons .

3 Kripton-84 dan Kripton-86 dikenali sebagai isotop bagi kripton. Jadi, isotop mempunyai ciri-ciri

kimiayangsama keranatindakbalaskimiamelibatkanelektrondalamatomtersebut.

Krypton-84 and Krypton-86 are known as isotopes of krypton. So, isotopes have the same chemical properties because chemical reactions involve the electrons in an atom.

4 Seterusnya,isotopmempunyaiciri-ciri fizikalyangberbeza kerana jisimnya berbeza.

Therefore, isotopes have different physical properties because their mass is different.




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KeradioaktifanRadioactivity

Keradioaktifanadalah penyusutansecaraspontan nukleusyang tidakstabil

menjadinukleusyanglebih stabil denganmemancarkan zarahbertenaga

(sinaranradioaktif)ataufoton.

Radioactivity is the spontaneous disintegration of an unstable nucleus into a

more stable nucleus accompanied by the emission of energetic particles (radioactive rays) or

photons.

Atau/Or

Adalahreputansecara spontan danrawaksatunukleusyangtidakstabilkepadanukleus

yangstabildenganmemancarkanzarah alfa , beta atausinar gama .

Is the spontaneous and random decay of an unstable nucleus into a more stable nucleus with emissions

of alpha , beta or gamma radiation.

ProsesspontanSpontaneous process

Merujukkepadaprosesyangtidakdipengaruhiolehfaktorluarseperti suhu ,

tekanan , medanelektrik dan medanmagnet .

Refers to a process that is not triggered by any external factors such as temperature ,

pressure , electric fields or magnetic fields .

SinaranelektromagnetElectromagnetic radiation

Ialahgelombangelektromagnetyangterdiridaripadakumpulantenagakecilyangdipanggil

foton .

Is electromagnetic waves that consist of small energy packets called photons .

PancaranradioaktifRadioactive emission

Jugadikenalisebagai zarahyangbertenaga atau foton ,sepertizarahalfa,

zarahbetadansinargama.

Also known as energetic particles or photons , such as alpha particle, beta particle and

gamma ray.

ReputanradioaktifataupenyusutanradioaktifRadioactive decay or radioactive disintegration

Prosesyangmananukleusyangtidakstabilberubahkepadanukleusyanglebihstabildenganmemancarkansinarradioaktif.Is the process in which an unstable nucleus changes into a more stable nucleus by emitting radiation.

Menganalisis Reputan Radioaktif Analysing Radioactive Decay

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BandingkansifatsemulajaditigajenissinaranradioaktifCompare the three kinds of radioactive emissions in terms of their nature

SinaranradioaktifRadioactive emissions

Zarahalfa,αAlpha particle, α

Zarahbeta,βBeta particle, β

Sinargama,Gamma ray, γ

SemulajadiNature

Nukleushelium/Helium nuclei

4

2He

Elektronberhalajutinggi Electrons with high velocity

0

–1e

GelombangelektromagnetElectromagnetic Wave

JisimMass

Jisimnyajauhlebihbesar daripadajisim

zarahbeta

Its mass is much bigger than that of a beta particle

Jisimnyajauhlebih kecil daripadajisimzarahalfa

Its mass is much smaller than that of an alpha particle

0(zero)

CasCharge

Cas positif

Positive charge

Cas negatif

Negative charge Neutral

KuasapengionanIonising power

Tinggi/High Sederhana/Medium Rendah/Low

KuasapenembusanPenetrating power

Rendah/Low SederhanaMedium

Sangattinggi/Very high

DiberhentikanolehStopped by

sehelaikertas

A sheet of paper

Beberapa mmaluminium

A few mm of aluminium

Beberapa cmplumbum

A few cm of lead

LajuSpeed

Lajunya lebihrendah

daripadalajuzarahbetaLower than the speed of a

beta particle

Lajuyang sangat

tinggi yangmencapai90%lajucahaya

Very high speed which is up to 90% of the speed of light

Bergerakdengan laju cahaya dalamvakum

Move at the speed of light in a vacuum

Ciri-ciriSinaranRadioaktifCharacteristics of Radioactive Emissions

KesanpengionanIonising effect

KuasapenembusanPenetration power

Interaksidenganmedanelektrikdanmedanmagnet

Interaction with electrical field and magnetic field

Pengionanatommenghasilkanion-ion

positif danion-ion negatifThe ionisation of an atom produces

positive ion and negative ionsAlfa/Alpha

(a) Tumpat/Dense

(b) Runutyang lurus

Straight tracks

(a) Sinarradioaktifyangmempunyaikuasapengionanyangpalingtinggiakanmempunyaikesanpenembusanyang

palingrendah .Radiation which has the strongest

ionising power will have the

lowest penetration effect.

(a) Pesonganzarahbeta lebih

besar darizarahalfa

keranajisimbeta lebihkecil darijisimalfa.The deflection of beta particles is

larger than alpha particles

becuase beta particles have a

smaller mass than that of alpha particles.




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(c) Zarahalfayangmempunyaijisimdanmomentumyangbesarmaka

ia tidakmudahterpesong Alpha particle has a large mass and momentum so it is

not easily deflected

(d) Zarahalfamenghasilkanbanyakpasanganiondalammedium.Alpha particles produce the most ion pairs in a medium.

ZarahalfaAlpha particle

Beta

(a) Zarahbetayangsangatlajumempunyairunutyang

nipisdanlurus The faster beta particle has

thin straight tracks

(b) Zarahbetayanglebihperlahanmempunyairunutyang

pendek dan tebal melengkungkearahrawak.The slower beta particles have

short and thick tracks which curve in random directions.

ZarahbetaBeta particle

Gama/GammaSinarangamatidakmenghasilkanrunutyangtebal,jelasdan

berterusan keranakuasapengionanyangpalingrendah.The gamma rays do not produce thick, clear

and continuous tracks due to

their low ionising power.

SinarangamaGamma ray

(b) Sinaranradioaktifakankehilangansebahagian

tenaganya setiapkalipasanganiondihasilkan.The radioactive emission loses some of

its energy each time an ion pair is produced.

(c) Zarahalfakehilangan tenaga sangatcepatsemasabergerakmelaluimedium.

Alpha particles lose energy very quickly as they move through a medium.

(d) Olehitu, zarahalfa mempunyaikuasapenembusan

yang palingrendah .

So alpha particles have the

lowest penetrating power.

zarahαα-particles

zarahββ-particles

sinarγγ-rays

SehelaikertasA sheet of paper

Aluminium(beberapa

mm)Aluminium(A few mm)

Plumbum(beberapa

cm)Lead

(A few cm)

(b) Sinarangama tidak

terpesong keranaiatidakmembawacas.

Gamma rays are not deflected

because they do not carry any charge.

MedanelektrikElectric field

zarah-ββ-particles

zarah-αα-particlessinar-γγ-raysRadioactive source

Sumberradioaktif

MedanmagnetMagnetic field

Zarahalfa dan zarahbeta

akan terpesong apabilamereka

melepasimedanmagnettetapi

sinarangama tidakdipesongkan .

Alpha particles and beta

particles are deflected when they

pass through a magnetic field while gamma

rays are not deflected .

MedanmagnetkedalamkertasMagnetic field into the paper

Petunjuk/Key:

α,β,γα,β,γ

αα

ββ

γγ




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Reputanradioaktif:Radioactive decay:

1 Apabila nukleus radioaktif mereput, nukleus akan pecah dan memancarkan zarahalfa atauzarahbeta dan tenaga .Iamenghasilkan atombaru bagiunsuryangberbeza.

When a radioactive nucleus decays, its nucleus break up and emits an alpha or beta particle and energy . It forms a new atom of a different element.

2 Selepasreputanradioaktif,bilangan proton dan neutron dalamnukleusakanberubah.

After radioactive decay, the number of protons and neutrons in the nuclei will change.

(a) Reputanalfa/Alpha decay Persamaanbagireputanalfa:/The general equation of alpha decay is:

A

ZX A – 4

Z – 2Y + 4

2 He + EnergyA

ZX A–4

Z–2Y+4

2He+TenagaParentnuclide

NukleusInduk

Daughternuclide

Nukleusanak

Alphaparticle

Zarahalfa

• Dalamreputanalfa,nukleusyangtidakstabilmemancarkan zarahalfa .

In alpha decay, the unstable parent nuclide emits an alpha particle.

• Nombor proton Zakandikurangkansebanyak2dannombor neutron ,Adikurangkansebanyak4padanukleousanak.

The daughter nuclide, its proton Z reduced by 2 and the neutron nombor, A its reduced by 4.

Contoh / Example

Isikantempatkosongdenganjawapanyangbetul.Fill in the blanks with the correct answers.

(a)238

92U Th+4

2He (b)210

84Po 206

82Pb+Penyelesaian/ Solution

(a)234

90Th (b)4

2He

(b) ReputanBeta/Beta Decay Persamaanbagireputanbeta:/The general equation of beta decay is:

A

ZX A

Z+1Y+0

–1e+Tenaga

Nukleusinduk

Nukleusanak

Zarahbeta

A

ZX A

Z + 1Y + 0

–1e + EnergyParentnuclide

Daughternuclide

Betaparticle

Apabila nukleusmereput denganmemancarkan zarah beta , maka nombor proton Z

ditambahsebanyak1tetapinombor neutron ,A,tidakberubah.

When a nuclide decays by emitting a beta particle, its proton number Z increases by 1 and its neutron number, A does not change.

Contoh / Example


(a)90

38Sr Y+0

–1e




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(b)40

19K 40

20Ca+Penyelesaian/Solution

(a)90

39Y (b)

0

–1e

(c) ReputanGama/Gamma Decay (i) Sinaranelektromagnetyangberfrekuensitinggidibebaskandaripadanukleusyangtelahmereput

dipanggilsinar gama .

High frequency electromagnetic radiation coming from a decaying nucleus is called gamma radiation. Persamaanreputangama: The general equation of gamma decay is:

A

ZX AZX+γTenagatinggi

Tenagarendah

A

ZX A

ZX + γHigher energy

Lower energy

(ii) Dalamreputangama,nukleusdalamkeadaanteruja(parastenagayanglebihtinggi)memancarkansinarγuntukmenukarkepadaparastenagayanglebihrendah.

In gamma decay, a nucleus in an excited state (higher energy state) emits a γ-ray to change to a lower energy state. (iii) Sinar gama dipancarkan sama ada bersama dengan zarah alfa atau beta dalam masa yang

sama. Gamma rays are emitted at the same time together with either alpha or beta particles.

(iv) Tiadaperubahandalamnombor nukleon dannombor proton .

There is no change in the nucleon number and proton number.

Contoh / Example


(a)60

27Co Co+γ

(b)83Bi

214

84Po+0 e+γ

(c) 232

90Th 208

82Pb+4

2He+0

–1e+γ Berapakahzarahalfadanzarahbetayangdipancarkanapabila

232

90Thmereputmenjadi208

82Pb? How many alpha particles and beta particles are emitted when

232

90 Th decays into 208

82 Pb ?

Penyelesaian/ Solution

(a) A=60 Z=27

(b)214

83Bi,0

–1e

(c)232

90Th→208

82Pb+64

2He+40

–1e+γ




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SiriReputanA decay seriesKadangkalanukleusanak(nukleusbaru)bagiunsurradioaktif,masihlagitidakstabil.Ianyaakanmereputkepada

nukleuslainyangjugatidakstabil.Prosesiniberterusandandikenalisebagai siripereputanradioaktif

sehinggamenghasilkan nukleusyangstabil .Sometimes the daughter nuclide of a radioactive nucleus is still unstable. It will eventually decay into another nuclide which is also

unstable. This process continues and it is called a radioactive decay series until a stable nuclide is produced.

238

92U 234

90Th 234

91Pa 226

88Ra 230

90U 234

92Uα ββ α α

Contoh / Example

238

92U 234

90Th 23491Pa 234

92U 226

88Ra

1 RajahdiatasmenunjukkansebahagiandarireputanradioaktifUranium-238.The diagram above shows part of an Uranium-238 radioactive decay series.(i) UraniumU-238mereputkepadathoriumTh-234.Tulissatupersamaanuntukmenunjukkanproses

reputan.Uranium-238 decays to Thorium-234. Write an equation to show the decaying process.

(ii) TerangkanperubahandalamnukleusUranium-238semasaprosesmereput.Explain the changes in the nucleus of Uranium-238 during the decaying process.

(iii) Tentukanbilanganzarahalfadanzarahbetayangdihasilkanolehsiripereputanradioaktif.Determine the number of alpha particles and beta particles produced by the radioactive decay series.


(i)238

92 U 234

90 Th+4

2He (ii) Semasareputanalfa,nomborprotonakanberkurangsebanyak2dannomborneutronjugaakan berkurangsebanyak2ataunombornukleonberkurangsebanyak4. During the alpha decay, the number of protons decreases by 2 and the number of neutrons also decreases by 2, that is, the nucleon number decreases by 4. (iii) 3zarahalfadan2zarahbeta. 3 alpha particles and 2 beta particles.

2 Rajahmenunjukkansirireputanradioaktif.The diagram shows part of a radioactive decay series.

Nombornukleon,ANucleon number (A)

Nomborproton,ZProton number (Z)

22287 88 89 90 91 92

226

230

234

238

III

II

I

NamakanzarahatausinaranradioaktifyangdipancarkandalambahagianI,IIdanIII.Name the particles or radiations emitted at parts I, II and III.




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Penyelesaian/ Solution I :Zarahalfa/Alpha particle II :Zarahbeta/Beta particle III :Zarahbeta/Beta particle

SetengahhayatHalf-life

Setengahhayatbagiunsurradioaktifialah masayangdiambil untukatomyangtidakstabilmereputmenjadi

setengahdaripadanilaiasalatausetengahhayat ialahmasayangdiambiluntuk keaktifannya

berkurangmenjadi setengah daripadanilaiasalnya.

The half-life of a radioactive element is the time taken for the unstable atoms to decay to half of its original value or,

half-life is the time taken for its activity to fall to half of its original value.

Contoh / Example

1 Setengahhayatunsurradioaktifyangberjisim40gialah2jam.Tentukanjisimunsurradioaktifyangsudahmereputselepas6jam.The half-life of a radioactive material of mass 40 g is 2 hours. Determine the mass of the radioactive material that has decayed after 6 hours.

PenyelesaianSolution

40g 20g 10g 5g

Selepas6jam,35gsudahmereputSo after 6 hours, 35 g has decayed

2 jam / hours 2 jam / hours 2 jam / hours

2 Setengah hayat untuk Natrium-24 ialah 16 jam. Berapakah masa yang diambil untuk Natrium-24 untukmenyusutdari0.64gkepada0.04g?The half-life of Sodium-24 is 16 hours. What is the time taken for Sodium-24 to shrink from 0.64 g to 0.04 g?

PenyelesaianSolution

0.64g 0.32g 0.16g 0.08g 0.04g

Masayangdiambil=16jam×4=64jamTime taken = 16 hours × 4 = 64 hours

16 jam / hours 16 jam / hours 16 jam / hours 16 jam / hours




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3 SetengahhayatuntukBa-143ialah12saat.BerapakahmasayangdiambiluntukaktivitiBa-143berkurang

kepada1

16daripadanilaiasalnya?/The half-life of Ba-143 is 12 seconds. How long will it take for the activity of a Ba-

143 sample to be reduced to 116 of its original value?

[Perhatian:"Unit"disinimewakiliunitaktiviti./Note : "Unit" here is used to represent the unit of activity.]


1unit 12

unit 14

unit 18

unit 116

unit

Masauntukberkurangkepada116

unit=12s×4=48s

The time taken to be reduced to 116 unit = 12 s × 4 = 48 s

12 s 12 s 12 s 12 s

4 Rajahmenunjukkangrafaktivitilawanmasauntuksuatubahanradioaktif.The diagram shows the graph of activity against time for a radioactive material.

Aktiviti/bilanganminit–1

Activity / counts minute–1

120

60

0 20 70Masa/minitTime / minutes

Berdasarkangrafdiatas,tentukansetengahhayatbagiunsurradioaktiftersebut.Based on the graph above, determine the half-life of the radioactive material.


Masayangdiambilolehbahanradioaktifuntukmenjadisetengahdariaktiviti120bilanganperminitkepada60 bilanganperminit =70minit–20minit=50minit The time taken for the radioactive material to become half of its activity from 120 counts per minute to 60 counts per minute = 70 minutes – 20 minutes = 50 minutes

Olehitu,setengahhayat,T12=50minit

Therefore the half-life, T12 = 50 minutes

5 Pelajarmenjalankansatueksperimenuntukmengetahuihubunganantarakadarreputandanmasa. Keputusaneksperimenmenunjukkangrafaktivitilawanmasadalamrajahdibawah.

A student carries out an experiment to find out the relationship between decay rate and time. The result of the experiment is shown in the graph of activity against time at the diagram below.

100

200

300

400

500

10

Aktiviti/bilanganperminitActivity / counts per minute

Masa/jamTime/hour3 42 5

KBAT




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(a) AktivitiNobolehdidapatkandaripintasanaktiviti.Tunjukkanpadagraf,bagaimanauntukmenentukanN

o

dannyatakannilaitersebutdidalamruangdibawah.Activity N

o can be obtained from activity intercept. Show on the graph how you would determine N

o and state the value

at the space given below.

No=

(b) Nyatakanhubunganantaraaktivitidanmasa./State the relationship between activity and time.(c) Darigraf,/From the graph,

(i) tentukan setengah hayat, T12 bagi unsur radioaktif. Tunjukkan di dalam graf bagaimana untuk

menentukanT12.

determine the half-life, T12 , of the radioactive element. Show on the graph how you determine T1

2.

(ii) carinilaiaktivitiyangmasihtinggalselepas4jam. find the value of the activity left after 4 hours.

(d) Nyatakandualangkahberjaga-jagayangperludiambilsemasamengendalikanunsurradioaktif.State two precautions to be taken when handling radioactive elements.


(a) Grafmenunjukkan/ As shown on the graph: N

0=500bilanganperminit/ N

0 = 500 counts per minute

(b) Aktivitiberkurangsecaraeksponendenganmasaataukeaktifanberkurangdenganmasa,t Activity decreases exponentially with time or the activity decreases with time, t

(c) (i) GrafmenunjukkanT12=1.5jam/ As shown on the graph, T1

2 = 1.5 hour

(ii) Grafmenunjukkan,/ As shown on the graph, Bakiaktiviti=90bilanganperminit The activity left = 90 counts per minute (d) 1. Sumberradioaktifharusdikendalikandengansistemkawalanrobotdisebalikbesi,konkrit,plumbumdan panelgelasplumbumyangtebal. Radioactive sources should be handled with robotic control systems behind steel, concrete, lead or thick lead glass

panels. 2. Lencanaradioaktifyangmengandungifilemfotografiperludipakaiuntukmemantaudossinaranyang

diterima. Radiation badges containing photographic film should be worn to monitor exposure to radiation.



RadioisotopRadioisotope

Radioisotopadalahisotopyang tidakstabil yangmananukleusyangtidakstabilnya

mereputdanmemancarkan sinarradioaktif sepertiα,β,γ.Radioisotopes are unstable isotopes with unstable nuclei which decay and emit radioactive emissions

like α, β, and γ.

Memahami Kegunaan Radioisotop Understanding the Uses of Radioisotopes

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Aplikasiradioisotop/Applications of Radioisotopes

BidangField

Jenisradioisotop

Type of radioisotope

PenggunaanradioisotopUses of the radioisotope

PerubatanMedicineRadioisotopdigunakandalamdiagnosispenyakittertentu,untukmendapatkanmaklumatbagitentangorganyangkhususbagipesakitataumerawatpenyakit.Radioisotopes are used in the diagnosis of certain diseases, provides information on the specific organs of a patient or treat diseases.

Natrium-24Sodium-24

• Iamempunyaisetengahhayatselama 15jam dandigunakan

untukmengesankedudukan darahbeku (thrombosis)dalam

salurdarah .

It has a half-life of 15 hours and is used to detect the positions of blood clots (thrombosis) in veins .

• Natrium-24disuntikkedalamsalurandarahdansinar gama dansinarbetayangdipancardikesanolehkamerasinardariluarbadan.

Sodium-24 is injected into the blood stream and gamma rays and beta rays emitted are detected by a ray camera outside the body.

Teknetium-99Technetium-99

• Iamempunyaisetengahhayatselama 6jam dandigunakan

untukmengkaji darahdalamjantung .

It has a half-life of 6 hours and is used to study the blood in the heart .

• Iahanyamemancarkansinaran gama dantidakmenghasilkanzarahalfaatauzarahbetayangberbahayadidalambadan.

It emits only gamma rays and produces no harmful alphas or betas inside the body.

Xenon-133Xenon-133

• Iamempunyaisetengahhayatselama 5hari dandigunakan

untukmengkajifungsi paru-paru .

It has a half-life of 5 days and is used in studying lung functions.

• Pesakitdimintauntukbernafasmenggunakanudarayangmengandungigasxenon-133.A patient is asked to breathe air containing the gas xenon-133.

• Sinaran gama yangdipancarkandikajimenggunakankameragamayangmenghasilkangambarparu-parupesakitdarisinarangamayangditerima.

The gamma rays emitted are studied using a gamma camera which produces a picture of patient’s lungs from the gamma radiation each one receives.

• Pesakitkemudiannyaakanmenghembuskeluarsemuaxenondanhanyamenerimasinarandaridosyangkecil.The patient soon breathes out all the xenon and receives only a tiny dose of radiation.

Iodin-131Iodine-131

• Iamempunyaisetengahhayatselama 8hari .Iamemancarkansinargamadandigunakanuntukmengesan

perubahandalamkelenjartiroid .

It has a half-life of 8 days . It emits gamma rays and is used for

detecting changes in the thyroid glands .

Iodin-123Iodine-123

• Iamempunyaisetengahhayatselama 13jam .Iadigunakan

untukmengesan buahpinggangyangtersumbatdalampesakit .

It has a half-life of 13 hours . It is used to detect blockage in the

kidneys of patients.




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Iodine-125Iodine-125

• Iamempunyaisetengahhayatselama 60hari .Iadigunakan

untuk menganggarkanjumlahdarah denganmenyuntikserumalbumin(HSA)yangtelahditentukanisipadunya.

It has a half-life of 60 days . It is used to estimate the volume of blood by injecting a measured volume of human serum albumin (HSA).

Kobalt-60Cobalt-60

• Iamempunyaisetengahhayatselama 5tahun .Iadigunakansecarameluasuntukmengubatipenyakitdenganmemberikandossinar

gama yangbanyakuntuk mengubatikanserdalaman .

It has a half-life of 5 years . It is widely used to give patients a large dose

of gamma radiation for the treatment of internal cancers . • Alursinargamadipancarkantepatkepadakanserdaripadasumberkobaltdiluar.A restricted beam of gamma radiation is carefully directed at the cancer site from an external cobalt source.

PerindustrianIndustry

Strontium-90Strontium-90

• Iamempunyaisetengahhayatselama 29tahun .Iadigunakan

untukmengukur ketebalankertas dalamperindustriankertas.

It has a half-life of 29 years . It is used to measure the thickness

of paper in paper industry.

• Iamemancarkanzarah beta .

It emits beta radiation.

Natrium-24Sodium-24

• Iamempunyaisetengahhayatselama 15jam yangdigunakan

untukmenguji kebocoranpaipdibawahtanah .Natrium-24ditambahkandalamairdalamtangkipenyimpanan.

It has a half-life of 15 hours and is used to test for leakage of

underground pipes . Sodium-24 is added into the water in storage tank. • TiubG-Mdigerakkandiataspaipbawahtanah,kebocorandapatdikesan.A G-M tube is moved above the underground pipe, a leakage can be detected.

Polonium-210Polonium-210

• Iamempunyaisetengahhayatselama 140hari .Iamemancarkan

zarahalfa.Iadigunakanuntuk meneutralkancasstatikplatfotografi ataucaspadapakaian.

It has a half-life of 140 days . It emits alpha radiation. It is used to

neutralise static charges in photographic plates or charges on clothes.

• Zarahalfa mengionkanzarah-zarahudarakepadaionpositifdanionnegatifyangmanaiameneutralkanplatfotografiataupakaian.

The alpha particles ionise the air particles into positive and negative ions which neutralise the photographic plates or the clothes.

Kobalt-60Cobalt-60

• Iamempunyaisetengahhayatselama 5tahun .Iadigunakan

untukmengesankimpalandalam strukturkeluli dansaluranpaip.

It has a half-life of 5 years . It is used to check welds in steel structures and pipelines.

• Sinaran gama darisumberkobalt-60yangbesardiletakkandisisistrukturkeluliyangterdedahdanplatfotografidiletakkandisisiyangbertentangan.

Gamma radiation from a large cobalt-60 source placed on one side of a steel structure exposes a photographic plate at the other side.




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Americium-241Americium-241

• Iamempunyaisetengahhayat 430tahun .Iadigunakandalam

pengesanasap .

It has a half-life of 430 years . It is used in a smoke alarm

.

• Americium-241memancarkanzarah beta yangmengionkanudara.

Americium-241 emits beta particles which ionise air. • Udarayangtelahdiionkankemudiannyaakanmengkonduksikanelektrikyangmembenarkanarusyangkecilmengalirmelaluinya.The air ions will then conduct electricity allowing a small current to flow through.

• Apabilaasapmemasukipenggera,zarahasapmasukmelaluizarah

beta, mengurangkan pengionandan arus melaluipenggera.When smoke enters the alarm, the smoke particles get in the way of the beta

radiation, thus reducing the ionisation and the current across the alarm.

PertanianAgriculture

Fosforus-32Phosphorus-32

• Iamempunyaisetengahhayatselama 14hari .Fosforus-32

digunakansebagaipenyurihuntukmengkaji keberkesananbaja .

It has a half-life of 14 days . Phosphorus-32 is used as a tracer in the

study of the effectiveness of fertilizers . • Tumbuh-tumbuhandisiramdengancecairyangmengandungifosforus-32.The plants are watered with a solution containing phosphorus-32.

Kobalt-60Cobalt-60

• Iamempunyaisetengahhayatselama 5tahun .Sinar

gama memancarkankobalt-60yangbolehdigunakandalam

pengawetanmakanan .

It has a half-life 5 years . The gamma radiation emits from

cobalt-60 can be used for food preservation .

• Sesetengahtempatsimpananmakanansepertibijirindankacangkering,selalunyadiserangolehseranggasemasadisimpan.Some foodstuffs, like grain and dried beans, are often attacked by pests while in storage.

• Rawatanpemancaranmembunuhseranggaperosakinidanmengurangkankerugian.Radiation treatment kill these pests and reduces the losses.

• Sinar gama jugadigunakanuntuk mengawalserangga

perosakyangmemusnahkantanaman .

The gamma radiation is also used to control insect pests

which damage crops .

ArkeologiArchaeology

Karbon-14Carbon-14

• Iamempunyaisetengahhayat 5700tahun .Iadigunakanuntuk

mengukurusiaspesimenarkeologi denganmenggunakankaedahpentarikhankarbon.

It has a half-life of 5 700 years . It is used to measure the age of archaeological specimens by carbon-dating method.

Uranium-238Uranium-238

• Iamempunyaisetengahhayatselama 5000jutatahun .

Iadigunakanuntukmengukur masageologi .

It has a half-life of 5 000 million years . It is used to measure the

geological time .




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Unitjisimatom(u.j.a.)Atomic mass unit (a.m.u.)

• Satu unitjisimatom (u.j.a.)ialahjisimbagisatuperduabelas

daripadajisimsatuatomkarbon-12,12

6C.

One atomic mass unit (a.m.u.) is 112

of the mass of the carbon-12 atom, 12

6C.

PembelahannukleusNuclear Fission

92143

• Pembelahannukleusadalah pemecahan satu nukleusyang

berat kepada duanukleusyanglebihringan ,sertamenghasilkanduaatautiganeutronbebasdanmembebaskan

tenaga yangsangatbesar.

Nuclear fission is the splitting of a heavy nucleus into two lighter nuclei , which emits either two or three neutrons and releases large

amounts of energy .

• Pembelahanberlakuapabilasatunukleus dihentam olehsatu

neutron .

Fission occurs when the nucleus of an atom is bombarded with a neutron .

TindakbalasberantaiChain reactions

NeutronNeutrons

U-235nukleusnucleus U-235

PembelahanspontanSpontaneous fission Lebihbanyak

pembelahanterhasildaripadahentamanbeberapaneutronMore fission triggered by neutrons

• Tindakbalasberantaiialah prosestindakbalaspengekalan yangmana

hasiltindakbalasinibolehmemulakantindakbalasseterusnya

yangserupa . (prosespembelahannukleusyangberterusan)

A chain reaction is a self-sustaining reaction in which the

products of a reaction can initiate another similar reaction .• Dalamtindakbalasberantai,pembelahanyangseterusnyabergantung

kepadapenghasilan nukleusbaru dan hentamanneutron .

In nuclear chain reactions the succession depends on the production and capture of neutrons .

• Satu neutron menghentam nukleusuranium maka2atau

3neutrondihasilkan.

A neutron bombards a uranium nucleus and 2 or 3 neutrons are produced.

• Neutronyangdihasilkaniniakanberlanggardengan nukleusuranium yanglain.

These neutrons produced will bombard another uranium nucleus .• Untuksetiaptindakbalas,lebihbanyakneutronterhasildan

menyebabkanberlakunya tindakbalasberantai ,sehinggajisim

nukleusuraniummencapai jisimgenting .

For each reaction, more neutrons are produced causing a chain reaction

until the mass of the uranium nucleus reaches a critical mass .

• Apabilaatomuraniummembelahsecaraberterusan,jumlahtenaga yangbesardibebaskanuntuksetiaptindakbalas.

As uranium atoms continue to split, a significant amount of energy is released during each reaction.

• Haba yangdibebaskanbolehdimanfaatkandandigunakan

untukmenjana tenagaelektrik .

The heat released is used to generate electrical energy .

Memahami Tenaga Nuklear Understanding Nuclear Energy

5.4




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• Tindakbalasberantaiyangterkawaldigunakandalamstesenkuasanuklear.A controlled chain reaction is used in nuclear power stations.

• Tindakbalasberantaiyangtidakterkawaldigunakandalam

bomnuklear .

An uncontrolled chain reaction is used in nuclear bombs .

JisimgentingCritical mass

• Jisimminimum bagi pembelahan nukleusyangakanmengekalkantindakbalasberantai.

The minimum mass of nuclear fission that will sustain a nuclear chain reaction.

PelakurannukleusNuclear fusion

NukleusDeuteriumDeuterium nucleus

DeuteriumDeuterium

NukleusHeliumHelium nucleus

2

1H+

2

1H

3

2H+

1

0n+Tenaga

Energy

+Tenaga Energy

• Pelakurannukleusadalah percantumanduanukleusyangringan

menjadinukleusyang lebihberat denganmembebaskan

tenaga yangsangatbesar.

Nuclear fusion is the combining of two lighter nuclei to form a heavier

nucleus with the release of large amount of energy .• Mataharimendapattenaganyadaripelakurannukleushidrogen.

The Sun get its energy from the fusion of hydrogen nuclei.

• Apabiladuaisotophidrogen-2nukleus berlanggardenganhalaju

yangtinggi ,iabolehbercantumdanmenghasilkannukleusyanglebihberat.Tenagayangbesardibebaskan.

When two hydrogen-2 nuclei moving at high speed collide , they combine together to produce a heavier nucleus. A large amount of energy is released.

• Suhu gasmesti tinggi supayanukleus-nukleus

yangringanmempunyai tenagakinetikpurata yangtinggi.

Disebabkankeperluansuhuyangtinggi,pelakurannukleusjugadikenali

sebagai tindakbalastermonuklear .

The temperature of a gas must be high , giving a high average kinetic energy . Due to the requirement of high temperature, nuclear

fusion is also known as a thermonuclear reaction .

TenaganuklearNuclear Energy

1 Kedua-duapembelahannukleusdanpelakurannukleusmembebaskan tenaga yangsangatbesar.

Both nuclear fission and nuclear fusion release a large amount of energy .

2 Sumbertenagainiadalahdaripada jisimyanghilang dalamtindakbalasnuklear.

The source of this energy is from the loss of mass in nuclear reactions.

3 Jumlah jisim zarahsebelumtindakbalasadalah lebihdaripada jumlahjisimzarahselepastindakbalas.

Cacatjisim(jisimyanghilang)=jumlahjisimsebelumtindakbalas–jumlahjisimselepastindakbalas

The sum of the masses of the particles before the reaction is more than the sum of the masses of the particles after the reaction.

Mass defect = sum of the masses before the reaction – sum of the masses after the reaction

4 Jisimyanghilang(cacatjisim)dalamtindakbalasberantaibermaksudbahawajisimtersebuttelahberubah

menjadi tenaga .

A loss of mass (or mass defect) in a nuclear reaction means that the mass has been changed to energy .




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5 MenurutAlbertEinstein,hubunganantarajisimdantenagadiberikanolehpersamaan:According to Albert Einstein, the relationship between the mass and the energy is given by the equation:

E = mc2

DimanaE=tenagadibebaskan/Where E = energy released m=jisimyanghilangataucacatjisim/m = loss of mass or mass defect c=halajucahaya=3×108ms–1/c = speed of light = 3 × 108 m s–1

Latihan / Exercise

1 Polonium-210mengalamireputanalfauntukmenjadiplumbum-206.PersamaanreputanialahPolonium-210 undergoes alpha decay to become plumbum-206. The equation for the decay is:

210

82Po

206

84Pb

4

2He Energy+ +

Maklumattambahan:/Additional information:

JisimPo/Mass Po =209.982a.m.u.

JisimPb/Mass Pb =205.969a.m.u.

JisimHe/Mass He =4.004a.m.u. 1a.m.u.=1.66×10–27kg c=3×108ms–1

210

82

206

84

4

2

210

82

206

84

4

2

Menggunakanpersamaandanmaklumatdiatas,kirakanUsing the equation and the information above, calculate (a) cacatjisim/the mass defect(b) tenagadibebaskan/the energy released


(a) Cacatjisim/Mass defect=Jisim/MassPo–(Jisim/MassPb+Jisim/MassHe) =209.982a.m.u.–(205.969a.m.u.+4.004a.m.u.) =0.009a.m.u. (b) E=mc2

=(0.009×1.66×10–27)kg×(3×108ms-1)2

=0.1345×10–11J =1.345×10–12J

2 Dalamujian letupannuklear,0.5guraniumtelahditukarkepada tenagadalammasa0.05µs.Berapakahkuasadalamletupannuklear?

[Halajucahaya=3.0×108ms–1]In a test of nuclear explosion, 0.5 g of uranium has been converted to energy in 0.05 µs. What is the power of the nuclear explosion?[Velocity of light = 3.0 × 108 m s–1]


Kuasa/Power,P= Et

= mc2

t

=(0.5×10–3)kg× (3.0×108ms-1)2

(0.05×10–6)s =9×1020W

210

82

206

84

4

2




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KelebihandankekuranganpenggunaanpembelahannuklearAdvantages and disadvantages of using nuclear fission

KelebihanAdvantages

KekuranganDisadvantages

• Kosmenggunakankuasanuklearsamasepertiarang,

jadiianya tidakmahal .

Nuclear power costs about the same as coal, so it isnot expensive .

• Iamenghasilkan tenaga yangsangat

besar denganhanyamenggunakanbahanapiyangsedikit.

It produces huge amounts of energy from small amounts of fuel.

• Terdapatbanyaksimpananbahanapinukleardidunia.Vast reserves of nuclear fuel in the world.

• Iatidakmenghasilkan asap atau

karbondioksida .

It does not produce smoke or carbon dioxide .

• Iatidakmenyumbangkepada kesanrumahhijau .

Iamenyebabkanpembaziranyang kurang berbandingdenganpembakaranbahanapi.

It does not contribute to the greenhouse effect . It

produces less waste than fossil fuels.

• Pusatkuasanuklear memerlukanbahanapiyangkurangberbandingdenganstesenyangmenggunakanbahanapifosil.

Nuclear power stations need less fuel than stations which use fossil fuels.

• Menghasilkan radioisotopyangberguna yangbolehdigunakandalamperindustrian,perubatan,pertaniandankajian.

Produces useful radioisotopes as by products that can be used in industry, medicine, agriculture and research.

• Langkah-langkahkeselamatandalampengurusanreaktornuklearadalahmajudanselamat.Safety procedures in the administration of nuclear reactors are very advanced and safe.

• Kospermulaanuntukmembentukdanmembinastesen

kuasanuklearadalah sangattinggi .

The initial cost to design and build a nuclear power station is very high .

• Berisikotinggiuntukberlakukemalanganjika

tindakbalasberantai hilangkawalan,meletupataukebocoranbahanradioaktifyangbesarbolehberlaku.Always a risk for accidents to occur if a

chain reaction goes out of control. Explosion or leakage of large amounts of radioactive substance may happen.

• Rodbahanapi yangdigunakansangatpanasdanmempunyaisetengahhayatyanglama.

Fuel rods used are very hot and highly radioactive with very long half-lives.

• Proseduryangmahaldiperlukanuntukmenyejukkanroddanmenyimpannya.

Expensive procedures are required to cool down the rods and store them.

• Airpanasyangdilepaskandaristesenkuasanuklear

bolehmenyebabkan pencemaranterma .

The hot water discharged from the nuclear power stations can

cause thermal pollution .

• Pekerjayangbekerjadipusatkuasanukleardanyang

tinggalberdekatanboleh terdedahkepada

pemancaranyangberlebihan .

People who work in the nuclear power station and those living

nearby may be exposed to excessive radiation

.

Kesedaran kepentingan pengurusan baik terhadap bahan radioaktifRealising the importance of proper management of radioactive substances

5.5




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CadangandanpeneranganSuggestions and explanation

CadanganSuggestions


Peralatanyangdigunakandalammenguruskansumberradioaktif.The equipment to be used in handling a radioactive source.

• Gunakanforsepataurobotkawalanjauh.Jarakantarasumberdanbadanmestilahjauh.Use forceps or remote control robot. Maintain a safe distance from the source.

• Pakaipenutupmukauntukmelindungimatadaripadaterdedahkepadapemancaran.Wear a mask to protect the eyes from radiation exposure.

• Pakaikotyangkalispemancaransupayapemancarantidakakanmenembusibadan.Wear a radiation-proof coat so that the radiation cannot penetrate the body.

• Pakailencanafilemuntukmengesankadarradiasiyangterdedah.Wear a film badge to detect amount of radiation exposed.

Pengubahsuaiandariaspekkaedahpenyimpananuntukmemastikanpenyimpanansumberradioaktifyangselamat.Modifications for storage method to ensure safe keeping of the radioactive source.

• Gunakankotakplumbumataukonkrityangtebal.Inibolehmenghalangradiasidaripadakebocorankekeadaansekeliling.Use a lead box or thick concrete. This can prevent radiation from leaking to the surrounding.

• Letakkansimbolpemancaranpadakotaksimpan.Iabolehmemberiamarankepadapenggunalainterhadapbahayadaripadasumberpemancaran.Put a radiation symbol on the storage box. It can warn other users about the danger of the radiation source.

Langkahberjaga-jagayangdiperlukanapabilamengendalikansumberradioaktif.Other precautions that need to be taken when handling a radioactive source.

• Pastikanmasapendedahanadalahdalamjangkamasayangsingkat.Keep exposure time as short as possible.

1 Rajah1menunjukkansinaran-sinaranradioaktifdidalammedanelektrik.Diagram 1 shows radioactive rays in electric field.

Sumberradioaktif

Radioactive source T

S

R

Rajah1/Diagram 1

Sinaryangmanakahmewakilizarahalfa?Which of the radioactive ray is alpha particles?

A RB SC T

atihan Pengukuhan / Enrichment ExerciseL2 Satu tengkorak manusia yang dijumpai

menunjukkankeradioaktifan30bilanganpersaat.Tengkorakbarumenunjukkankeradioaktifan120bilanganpersaat.Jikaseparuhhayatkarbon-14adalah5600tahun,berapausiatengkorakitu?An old human skull that has been found, produces radioactive rays with radioactivity of 30 counts per second. A new skull produces radioactivity of 120 counts per second. If the half life of Carbon-14 is 5 600 years, how old is the skull?

A 11200tahun/yearsB 22400tahun/yearsC 168000tahun/yearsD 672000tahun/years




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Jadual4menunjukkankeputusanpenyiasatan.Table 4 shows her results.

SinarlatarbelakangBackground count

25bilanganperminit25 counts per minute

BilangandengansumbersahajaCount with source only


BilangandengansumberdankertaspenghadangCount with source and paper absorber


Bilangandengansumberdanpenghadangaluminiumketebalan3mmCount with source and aluminium absorber 3 mm thick


Jadual4/Table 4

Sumberitumemancarkan/The source emitsA zarah-zarahalfadanbeta. alpha and beta particles.B zarahbetadansinargama. beta particles and gamma rays.C zarahbetasahaja beta particles only.D sinargamasahaja. gamma rays only.

5 Persamaan menunjukkan penyusutan jisimnukleusX.The equation shows the decay of the nuclide X.

226

88X P

QY+4

2He ApakahnilaiPdanQ?

What are the values of P and Q?

P Q

A 230 90

B 230 86

C 222 90

D 222 86

6 Tindakbalasnuklearbagisatunukleusradium-226mengalamicacatjisimsebanyak4.3409g.Hitungtenaga yang dibebaskan dalam tindak balasnuklearini.The nuclear reaction of one nucleus of radium-226 experiences a mass defect of 4.3409 g. Calculate the energy released in this nuclear reaction.

[c=3.0×108ms–1]A 1.954×10–13JB 3.907×10–13JC 7.814×10–13JD 1.293×10–14J

3 Seorangpelajaringinmengkajijenissinarradioaktifyangdipancarkanolehsumberradioaktif.Rajah3menunjukkansusunanradasyangdigunakan.A student wishes to study the type of radioactive radiation emitted by a radioactive source. The arrangement of the apparatus used is as shown in Diagram 3.

SumberradioaktifRadioactive source

TiubGeigerMuller

Geiger Muller Tube

PenyerapAbsorber Meterkadar

Rate meter

Rajah3/Diagram 3

Jadual 3 menunjukkan keputusan kajian yangdilakukan.Table 3 shows the result of the study.

PenyerapAbsorber

BacaanmeterkadarRate meter reading

Udara/Air 120

Kertas/Paper 119

Aluminium3mmAluminium 3 mm

50

Plumbum10cmLead 10 cm

50

Jadual3/Table 3

Apakahjenissinaryangdipancarkanolehsumberradioaktifitu?/What type of radiation is emitted by the radioactive source?A Zarahalfa/Alpha particleB Zarahbeta/Beta particleC Sinargama/Gamma rayD Zarahalfadanbeta/Alpha and beta particles

4 Seorang pelajar menyiasat tentang kuasapenembusansesuaturadiasidaripadasumbernyasepertiRajah4.A pupil investigates the penetrating power of radiation from a radioactive source as in Diagram 4.

1cm

TiubGeigerMullerGeiger Muller tube

PenyerapAbsorber

KepembilangTo counter

RadioaktifRadioactive

Rajah4/Diagram 4




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7 Persamaanberikutmewakilipelakurannukleus.The following equation represents a nuclear fusion.

2

1H+3

1H 4

2He+1

0n+TenagaEnergy Jikatenagayangdibebaskansemasatindakbalas

tersebutituialah5.64x10–12J,hitungcacatjisimdaripadatindakbalasitu.If the energy released in the above reaction is 5.64 × 10–12 J, calculate the mass defect from the reaction.

[1u=1.66×10–27kg;c=3.0×108ms–1]

A 0.009432uB 0.018863uC 0.037726uD 0.075452u

8 Jadual 8 menunjukkan maklumat bagi empatsampelradioaktif.

Table 8 shows the information of four different radioactive samples.

Sampelradioaktif

Radioactive sample

Setengahhayat

Half-life

Sinaranradioaktif

Radioactive emission

Kobalt-60Cobalt-60

5tahun5 years

GamaGamma

Strontium-90Strontium-90

28tahun28 years

BetaBeta

Iodin-131Iodine-131

8hari8 days

GamaGamma

Polonium-210Polonium-210

140hari140 days

AlfaAlpha

Jadual8 Table 8

Sampel manakah yang paling sesuai untukpemeriksaanginjal?

Which sample is most suitable to be used for examining the kidney?A Kobalt-60 Cobalt-60B Strontium-90 Strontium-90C Iodin-131 Iodine-131D Polonium-210 Polonium-210

9 Jadual9menunjukkanempatnuklidradioaktif. Table 9 shows the half-life of four radioactive nuclides.

NuklidradioaktifRadioactive nuclides

SetengahhayatHalf-life

Ga 4063s

Rn 50s

Bi 128s

Pb 1600s

Jadual9/Table 9

Reputan radioaktif salah satu daripada nuklidraddioaktif tersebut adalah ditunjukkan padaRajah9.

The radioactive decay for one of these radioactive nuclides is shown in Diagram 9.

10

20

30

40

50

60

200

Kadarbilang/bilangsesaatCount rate / counts per second

60 8040 100 120Masa/saatTime/seconds

Rajah9 Diagram 9

Yangmanakahmerupakannuklidradioaktifdalamgrafitu?Which is the decaying radioactive nuclide in the graph?

A GaB RnC BiD Pb

10 Pernyataan yang manakah benar tentangkegunaanbahanradioaktif?Which statement is true about the use of radioactive substance?

A Mengenalpastiwangkertaspalsu. To identify counterfeit bank notes.B Menentukan kandungan bagasi penumpang

kapalterbang. To determine the contents in the baggage of airplane

passengers.C Menentukanjantinajanindalamrahim. To determine the sex of a foetus.D Sebagaikawalanperosakdalampertanian. As pest control in agriculture.




UN

IT 5

UN

IT 5

1 Rajah1.1adalahsebahagianlengkungpereputansatusampelisotopradioaktifyangmemancarkansinaralfa(α).Diagram 1.1 is part of the decay curve for a sample of an α-emitting radioactive isotope.

25

50

75

100

50

%aktiviti% activity

15 2010

Masa/hariTime/days

Rajah1.1 Diagram 1.1

(a) Apakahmaksudisotop? What is meant by isotope?

Atomunsuryangmempunyainomborprotonyangsamatetapinombornukleonyangberbeza.

Atoms of elements which have same proton number, but different nucleon number.

(b) BerdasarkanRajah1.1, Based on Diagram 1.1,

(i) tentukanseparuhhayatisotop. determine the half-life of the isotope.

Daripadagraf,separuhhayatisotop=3.5hari.

From the graph, the half-life of the isotope = 3.5 days.

(ii) LengkapkanlengkungandalamRajah1.1sehinggamasa=20hari.Plotsecaratepathubungannilaiperatusaktivitidenganmasa.

Complete the curve in Diagram 1.1 as far as time = 20 days. Plot the exact corresponding values of the percentage activity and time.

(c) RadasditunjukkandalamRajah1.2bagieksperimenuntukmencarijulatzarahαdidalamudara. In an experiment to find the range of α-particles in air, the apparatus in Diagram 1.2 is set-up.

Sumberzarahαα-particle source

PengesanDetector

PembarisRuler

Rajah1.2 Diagram 1.2

oalan Struktur / Structure QuestionsS




UN

IT 5

UN

IT 5

KeputusaneksperimenditunjukkandalamJadual1. The results of this experiment are shown in Table 1.

Jarakantarasumberdanpengesan/cmDistance from source to detector / cm 1 2 3 4 5 6 7 8 9

Kadarpembilang(bilang/minit)Count rate (counts / minute) 681 562 441 382 317 20 19 21 19

Jadual1 Table 1

(i) Namakansatupengesanyangsesuaiuntukmengesanzarahαdalamudara. Name one suitable detector to detect α-particles in air.

TiubG-M

Geiger Muller tube

(ii) Nyatakansebabmengapaterdapatkadarbilanganpadajarak9cmdaripadasumber. State the cause of the count rate at a distance of 9 cm from the source.

BacaanLatarBelakang.

Background reading.

(iii) Anggarkankadarbilanganyanghanyadipengaruhiolehjarak2cmdaripadasumber. Estimate the count rate that is only due to the source at a distance of 2 cm.

562–20//19//21=542//543//541bilang/minit.

562 – 20//19//21 = 542// 543// 541 counts/min.

(iv) BerdasarkanJadual1,apakahjarakmaksimumzarahαbolehbergerakdalamudara. Using Table 1, what is the maximum distance α-particles can travel in air?

5cm

(v) Jastifikasijawapanandabagi(c)(iv). Justify your answer to (c)(iv).

1 Pada5cm,bacaandaripadapengesanmeningkatdengancepat.

At 5 cm, the reading form detector increase rapidly.

2 Dalamskala/bilanganyangbesar,menunjukkankewujudanzarahα.

In large scale/ number, shows the existing of α-particles.

2 Polonium-210adalahsatu radioisotopbagipolonium.Suatusampel radioisotopyangmengandungi400gPolonium-210mengalamiprosesreputan.Setengah-hayatPolonium-210adalah140hari.Polonium-210 is a radioisotope of polonium. A radioisotope sample that contains 400 g of Polonium-210 undergoes a decay process. The half-life of Polonium-210 is 140 days.(a) Apakahmaksudsetengah-hayat? What is the meaning of half-life?

Setengahhayatialahmasayangdiambiluntukjisim/aktivitiradioisotopmenjadiseparuhdaripadanilai

jisim/aktivitiasalnya.

Half-life is the time taken for the mass/activity of radioisotope to become half of its mass/activity.

(b) BerisatusebabmengapaPolonium-210mengalamiprosesreputan. State one reason why Polonium-210 undergoes a decay process.

Untukmenjadilebihstabil.

To become more stable.




UN

IT 5

UN

IT 5

(c) (i) HitungjisimPolonium-210selepas420hari. Calculate the mass of Polonium-210 after 420 days.

(ii) PadaRajah2,lakargrafuntukmenunjukkanprosesreputanPolonium-210. On Diagram 2, sketch a graph to show the decay process of Polonium-210.

400

200

300

100 300200 400

100

0

Jisim(g)Mass (g)

Masa/hariTime/days

Rajah2/Diagram 2

400g 100g140

200g140140

T1—2

T1—2

T1—2

50g

Selepas420hari,jisimPolonium-210yangmasihaktif=50g.After 420 days, the mass of Polonium-210 that is still active = 50 g.


modul f t 5 keradioaktifan 5 radioactivity · based on the graph above, determine the half-life of...

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