HIGHFIELDSSCHOOL

Physics Department

OCR GCSE Physics

P4 – Radiation for LifeStudent Support Booklet

Equations

P4 – Key WordsActivity Average number of nuclei that decay every secondAlpha particles Radioactive particles which are helium nuclei (helium

atoms with no electrons so they have a positive charge).

Alternating current or voltage

An electric current that is not a one way flow.

Ammeter Meter used in an electric circuit for measuring currentAmpere (A) The unit used to measure electric current, often

abbreviated to ampAmplitude The distance the wave moves from its rest positionAtomic number The number of protons found in the nucleus of an

atomBackground Radiation

Ionising radiation from space and rocks, especially granite, that is around us all the time but is at a very low level.

Becquerels (Bq) Unit of activity or count rate; 1 Bq = 1 count per second

Beta particles Particles given off by some radioactive materials (they have a negative charge)

Boron control rods Rods that are raised or lowered in a nuclear reactor to control the rate of fission

Carbon-14 A radioactive isotope of carbonChain reaction A reaction where the products cause the reaction to

go further or faster, e.g. nuclear fissionCharge(s) Can either be positive or negative. Opposite charges

attract. The same charges will repel each other.Circuit breakers Resettable fusesCold fusion Attempts to produce fusion at normal room

temperature that have not been validated since other scientists could not reproduce their results.

Compressions Particles push together, increasing pressureConductors Electrical conductors allow electricity to flow through

themCosmic rays Radiation from space that contributes to background

radiationCount rate Average number of nuclei that decay every secondcurrent Flow of electrons in an electric circuitDefibrillator Machine which gives the heart an electric shock to

start it beating regularlyDirect current An electric current that flows in one direction only.Double insulated An electric device in which there are at least two

layers of insulation between the user and the electric wires.

Earth wire The third wire in a mains cable which connects the case of an appliance to the ground so that the case cannot become charged and cause an electric shock

Earthed (electrically)

Connected to the ground at 0V

Electromagnetic waves

A group of waves that carry different amounts of energy – they range from low frequency radio waves to high frequency gamma rays

Electrostatic attraction

Attraction between opposite charges

Electrostatic dust precipitators

Charged plates inside factory chimneys remove dust particles from smoke

Electrostatic paint sprayer

Charges paint droplets to give even coverage

Enriched uranium Uranium containing more of the U-235 isotope than occurs naturally

Fission Splitting apart, especially of large radioactive nuclei such as uranium

Frequency The number of waves passing a set point per second.Fuel rods Rods of enriched uranium produced to provide fuel for

nuclear power stationsFuse(s) A special component in an electric circuit containing a

thin wire which is designed to melt if too much current flows through it, breaking the circuit

Fusion The joining together of small nuclei, such as hydrogen isotopes, at very high temperatures with the release of energy

Fusion bombs Hydrogen bombs or H-bombs based on fusion reactions

Gamma rays Ionising electromagnetic waves that are radioactive and dangerous to human health – but useful in killing cancer cells.

Geiger counter A device used to detect some types of radiationGeiger-Muller tube A device used to detect some types of radiationGel In ultrasound scanning, placed on the skin so that

nearly all the ultrasound passes into the body and is not reflected by the skin.

Generator Device that converts rotational kinetic energy to electrical energy

Granite Mineral containing low levels of uraniumGraphite A type of carbon used as a moderator in a nuclear

power station

Half-life Average time taken for half the nuclei in a radioactive sample to decay

Helium Second element in periodic table; an alpha particle is a helium nucleus

Hertz (Hz) Units for measuring wave frequencyIonises Adds or removes electrons from an atom leaving it

chargedIons Charged particles (can be positive or negative)Isotopes Atoms with the same number of protons but different

numbers of neutronsLead Heaviest element having a stable isotope; all isotopes

of the elements above it in the periodic table are unstable

Live wire Carries a high voltage into and around the houseLongitudinal wave Wave in which vibrations are in the same direction as

the direction in which the wave moves.Mass number The number of protons and neutrons in a nucleusModerator Material used to slow down neutrons in a nuclear

power stationNeutral wire Provides a return path for the current in a mains

supply to a local electricity substationNeutrons Small particle which does not have a charge found in

the nucleus of an atom.Nuclear equation Equation showing changes to the nuclei in a nuclear

reactionNuclear power stations

Power stations using the energy produced by nuclear fission to generate heat

Nucleons Protons and neutrons (both found in the nucleus)Pitch Whether a sound is high or low on a musical scalePotential difference Another word for voltage (a measure of the energy

carried by the electric current)Radioactive waste Waste produced by radioactive materials used at

nuclear power stations, research centres and some hospitals

Radiocarbon dating Method of dating some old artefacts using Carbon-14Radiographer A technician who works in a hospital radiography

department, possibly taking x-rays or treating some types of cancer with radiation

Radioisotope Isotope of an element that is radioactiveRadiotherapy Using ionising radiation to kill cancer cells in the bodyRarefractions Particles are further apart than usual, decreasing

pressureRatemeter A device that measures the amount of radiation

detected by a Geiger-Muller tube

Resistance Measurement of how hard it is for an electric current to flow through a material

Rheostat A variable resistorShock Occurs when a person comes into contact with an

electrical energy source so that the electrical energy flows through a portion of the body

Smoke detector Device to detect smoke, some forms of which contain a source of alpha radiation

Sparks Type of electrostatic discharge briefly producing light and sound

Stable (nucleus) (nucleus) is not radioactive; it will not decaySuperconductors Materials that conduct electricity with little or no

resistanceTracers A radioactive, radiation-emitting substance used to

follow movement of a particular chemical, e.g. nuclear medicine, tracking the path of an underground pipe, etc.

Transmitted Radiation passing through an objectTransverse wave Wave in which the vibrations are at right angles to the

direction the wave is movingUltrasound High-pitches sounds which are too high for detection

by human earsUranium Radioactive element with a very long half-life used in

nuclear power stationsVan de Graff generator

A machine which uses a moving belt to accumulate very high charges on a hollow metal globe

Variable resistor A resistor whose resistance can changeVoltage A measure of the energy carried by an electric current

(also called the potential difference)Voltmeter Instrument used to measure voltage or potential

difference in volts (V)Wavelength (λ) Distance between two wave peaksx-rays Ionising electromagnetic waves used in x-ray

photography (used to generate pictures of bones)

Module P4: Radiation for LifeP4a: SparksThe concept of medical physics runs through this item. Electrostatics plays an important part in our lives. We investigate some of the ideas of electrostatics and look at the problems caused.

GRADE G - D GRADE C GRADE B – A* Targets for Improvement

Recognise that when some materials are rubbed theyattract other objects:

• certain types of dusting brushes become charged and attract dust as they pass over it.

Recognise that insulating materials can become charged when rubbed with another insulating material.

State that there are two kinds of charge:• positive• negative.

Recognise that like charges repel and unlike chargesattract.

Understand that electrostatic phenomena are causedby the transfer of electrons, which have a negative charge.

Describe static electricity in terms of the movement ofelectrons:• a positive charge due to lack of electrons• a negative charge due to an excess of electrons.

Recognise that atoms or molecules that have become charged are ions.

Describe how you can get an electrostatic shock fromcharged objects:• synthetic clothing.

Describe how you can get an

Explain how static electricity can be dangerous when:• in atmospheres where explosions could occure.g. inflammable gases or vapours or with high

Explain how the chance of receiving an electric shockcan be reduced by:• correct earthing• use of insulating mats• using shoes with insulating

electrostatic shock if you become charged and then become earthed:• touching water pipes after walking on a floor covered with an insulating material e.g. synthetic carpet.

concentrations of oxygen

• in situations where large quantities of charge could flow through the body to earth.

Explain how static electricity can be a nuisance:• dirt and dust attracted to insulators (plastic containers, TV monitors etc.)• causing clothing to “cling”.

soles• bonding fuel tanker to aircraft.

Explain how anti-static sprays, liquids and cloths help reduce the problems of static electricity.

P4a Activities1. Fill in the gaps using the words in the box below.

electrons charge conductor rubbing attractrepel positively neutrons protons negativel

ymoving different friction insulator same

……………………….. a polythene rod gives it static electricity. Static means not ………………………..Atoms contain negatively charged particles called ……………………….., ………………………..charged particles called protons and neutral particles called ………………………..

When charged objects are brought near each other, they either ……………………….. or ……………………….. each other. What happens depends on their ………………………..

Two objects with the ……………………….. charge will ……………………….. each other, whilst oppositely charged objects will ……………………….. each other.

2. Draw an annotated diagram to show how a balloon rubbed against your hair is then able to stick to the wall.

3. Answer the following questions on static electricity:

a) What charge does a polythene rod acquire when rubbed with a duster?

……………………………………………………………………………………

b) Name the particles that have moved to make this happen.

……………………………………………………………………………………

c) Did these particles move from the polythene rod or from the duster?

……………………………………………………………………………………

d) What charge does an acetate rod acquire when rubbed with a duster and in which direction did these particles move?

……………………………………………………………………………………

e) What happens if two negatively charged objects or two positively charged objects are brought near each other?

……………………………………………………………………………………

f) What happens if a positively charged object is brought near a negatively charged object?

……………………………………………………………………………………

g) Jo combs her hair very hard. Some of her hair stands up a little. Explain why this happens.

……………………………………………………………………………………

……………………………………………………………………………………

Module P4: Radiation for LifeP4b: ElectrostaticsElectrostatics has many uses. This item looks at some of the uses both in medicine and everyday life and illustrates the use of contemporary scientific and technological developments and their benefits, drawbacks and risks.

GRADE G - D GRADE C GRADE B – A* Targets for Improvement

Recall that electrostatics can be useful for electrostatic precipitators:

• remove the dust or soot in smoke• used in chimneys.

Explain how static electricity can be useful for electrostatic dust precipitators to remove smoke particles etc from chimneys:• dust passes through charged metal grid or past charged rods• dust particles become charged• plates are earthed or charged opposite to grid• dust particles attracted to plates• plates struck and dust falls to collector.

Explain how static electricity is used in electrostatic dust precipitators to remove smoke particles etc from chimneys:

• high voltage metal grids put into chimneys to produce a charge on the dust

• dust particles gain or lose electrons

• dust particles induce a charge on the earthed metal plate

• dust particles are attracted to the plates.

Recall that electrostatics can Explain how static electricity Explain how static electricity

be useful for spraying:• spray painting• crop spraying.

can be useful for paint spraying:• spray gun charged• paint particles charged the same so repel giving a fine spray and coat• object charged oppositely to paint so attracts paint into the ‘shadows’ of the object giving an even coat with less waste.

is used in paint spraying, in terms of paint and car gaining and losing electrons and the resulting effects.

Recall that electrostatics can be useful for restarting the heart when it has stopped (defibrillator).

Recall that defibrillators work by discharging charge.

Explain how static electricity can be useful for restarting the heart when it has stopped (defibrillator):• paddles charged• good electrical contact with patient’s chest• charge passed through patient to make heart contract• care taken not to shock operator.

P4b Activities1. Label and annotate the diagram below to show how an electrostatic smoke precipitator works:

2. What is a defibrillator and how does it work?

…………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………3. Why are the handles of a defibrillator made from plastic?

………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

4. Static electricity can be used in the spray painting of car bodies.

(a) On the diagram show the charges on the spray-paint drops and on the car body.

(b) Carefully explain the process.

………………………………………………………………………………...………………………………………………………………………………...………………………………………………………………………………...………………………………………………………………………………...………………………………………………………………………………...………………………………………………………………………………...………………………………………………………………………………...………………………………………………………………………………...

5. Care must be taken when using electrostatics to spray-paint. What precautions can be taken by workers when spray-painting?

……………………………………………………………………………………

……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

Module P4: Radiation for LifeP4c: Safe ElectricsThis item investigates electricity. Safety is a major requirement when electricity is used in a medical situation. Here the principles of fuses and earthing are studied.

GRADE G - D GRADE C GRADE B – A* Targets for Improvement

Explain the behaviour of simple circuits in terms of the flow of electric charge.

Describe and recognise how resistors can be used to change the current in a circuit.

Describe how variable resistors can be used to change the current in a circuit:• longer wires give less current• thinner wires give less current(rheostat configured as a variable resistor only).

Recall that resistance is

Explain how variable resistors can be used to change the current in a circuit:• longer wires have more resistance• thinner wires have more resistance (rheostat configured as a variable resistor only).

Describe the relationships between current, voltage (pd) and resistance:• for a given resistor, current increases as voltage increases and vice versa• for a fixed voltage, current decreases as resistance increases and vice versa.

Use the equation:

Use and apply the equation, including a change of subject:

resistance= voltagecurrent

measured in ohms. resistance= voltagecurrent

Recall the colour coding for live, neutral and earth wires:• live – brown• neutral – blue• earth – green/yellow.

State that an earthed conductor cannot become live.

Describe the functions of the live, neutral and earth wires:• live – carries the high voltage• neutral – completes the circuit• earth – a safety wire to stop the appliance becoming live.

Describe reasons for the use of fuses and circuit breakers (as re-settable fuses).

Recognise that “double insulated” appliances do notneed earthing.

Explain how a wire fuse reduces the risk of fire; if theappliance develops a fault:• too large a current causes the fuse to melt• preventing flow of current• prevents flex overheating and causing fire• prevents further damage to appliance.

Use the equation:power = voltage × currentExplain why “double insulated” appliances do not need earthing:• the appliance is a non conductor and cannot become live.

Explain the reasons for the use of fuses and circuit breakers as re-settable fuses (structure and mode of operation not required).

Explain how the combination of a wire fuse and earthing protects people.

Use the equation, including a change of subject:

power = voltage × current

to select a suitable fuse

for an appliance.

P4c Activities1. Colour in the wires then label and annotate the plug to show how it works:

2. Complete the passage below to explain how a fuse works and why we sometimes need an Earth wire. Use the words from the box below:

Fuses are ………………… devices. If there is a fault in an appliance which causes the ………………… and neutral (or earth) wire to cross then a ………………… current will flow through the ………………… and cause it to ………………… . This will break the ………………… and protect the appliance and user from further ………………… .

Earth wires are always used if an appliance has a ………………… case. If there is a ………………… in the appliance, causing the live wire to ………………… the case, the current “…………………” down the earth wire and the …………………blows.

3. Which fuse should you use for:

large, harm, safety, fuse, fault, metal, surges, touch, melt, live, circuit, fuse

(a) A 2750 W kettle running on mains electricity (230 V)? ………………………………………………………………………………………………………………………………………………………………………………………(b) A 1 kW kitchen appliance running on mains electricity? ………..…………………………………………………………………………………………………………………………………………………………………………4. Give three advantages of using a RCCB (Residual Current Circuit Breaker) over a fuse?

………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………5. Complete the following sentences:

For a given resistor, as you increase the voltage you ………………… the current.

For a fixed voltage, as you decrease the resistance you ………………… the current.

A longer wire will have ………………… resistance. A thicker wire will have ………………… resistance.

6. Use the equation sheet to help you complete the following table:

Voltage Current Resistance2.6 A 220 Ω

230 V 10 A0.5 mA 47 kΩ

4 kV 1.6 MΩ1.5 kV 50 A

Module P4: Radiation for LifeP4d: UltrasoundThe concept of medical physics runs through this item. Ultrasound is an important medical diagnostic and therapeutic tool. This item looks at the properties of longitudinal waves, and investigates some of the medical uses of ultrasound.

GRADE G - D GRADE C GRADE B – A* Targets for Improvement

Recall that ultrasound is a longitudinal wave.

Recognise features of a longitudinal wave:• wavelength• compression• rarefaction.

Describe features of longitudinal waves:• wavelength• frequency• compression (a region of higher pressure)• rarefaction (a region of lower pressure).

Recall that the frequency of ultrasound is higher than the upper threshold of human hearing (20 000 Hz) because the ear cannot detect these very high frequencies.

Describe and compare the motion and arrangement of particles in longitudinal and transverse physical waves:

• wavelength

• frequency

• compression

• rarefaction

• amplitude.

Recognise that ultrasound can be used in medicine for diagnostic purposes:• to look inside people by scanning the body

Recognise that ultrasound can be used in medicine for non-invasive therapeutic purposes such as to break down kidney and other

Explain how ultrasound is used in:• body scans (reflections from different layers returning at different times from different

• to measure the speed of blood flow in the body(candidates are not expected to describe the Doppler effect).

stones. depths)• breaking down accumulations in the body such as kidney stones.

Explain the reasons for using ultrasound rather than X-rays for certain scans:• able to produce images of soft tissue• does not damage living cells.

P4d Activities1. Label the feature of a longitudinal wave below to include:

Wavelength Amplitude Rarefaction Compression

2. Draw and label a transverse wave in the box below to include: wavelength; amplitude; trough; crest/peak and rest position.

3. What is ultrasound? (you must refer to its frequency in your answer)

………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………4. Give three uses of ultrasound.

……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………5. Explain how ultrasound is used for fetal scanning. …………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………6. Why is ultrasound used for fetal scanning and not x-rays?

……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

Module P4: Radiation for LifeP4e: What is radioactivity?Nuclear radiation is often misunderstood and frightening. Many people will come across nuclear radiations in everyday life. This item explores the properties and uses of nuclear radiation.

GRADE G - D GRADE C GRADE B – A* Targets for Improvement

Recognise that the radioactivity or activity of anobject is measured by the number of nuclear decaysemitted per second.

Understand that radioactivity decreases with time.

Recall that nuclear radiation ionises materials.

Describe radioactive substances as decayingnaturally and giving out nuclear radiation in the form of alpha, beta and gamma.

Explain and use the concept of half-life.

Interpret graphical data of radioactive decay to include a qualitative description of half-life.

Explain ionisation in terms of:• removal of electrons from particles• gain of electrons by particles.

Interpret graphical or numerical data of radioactive decay to include calculation of half-life.

Explain why alpha particles are such good ionisers.

Recall that radiation comes from the nucleus of the atom.

Describe radioactivity as coming from the nucleus of an atom that is unstable.

Recall that an alpha particle is a helium nucleus.

Recall that a beta particle is a fast moving electron.

Describe what happens to a nucleus when an alpha particle is emitted:• mass number decreases by 4• nucleus has two fewer neutrons• nucleus has two fewer protons• atomic number decreases by 2• new element formed.

Describe what happens to a nucleus when a beta particle is emitted:• mass number is unchanged• nucleus has one less neutron• nucleus has one more proton• atomic number increases by one• new element formed.

Construct and balance nuclear equations in terms of mass numbers and atomic numbers to represent alpha and beta decay.

P4e Activities1. For each of the statements below, decide if they are true or false Re-write any false statements to make them true.

Statement True False

1. Radioactivity is measured by the number of nuclear decays emitted per second.

2. Radioactivity increases with time.3. An alpha particle is the same as a helium

atom.4. Nuclear radiation ionises materials.5. Beta particles are fast moving high energy

electrons.6. Radiation comes from the electrons of the

atom that is stable.

……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………2. (a) Define ionisation.

……………………………………………………………………………………(b) How does a material become positively ionised?

……………………………………………………………………………………(c) How does a material become negatively ionised?

……………………………………………………………………………………3. What is the definition of half-life?

…………………………………………………………………………………………………………………………………………………………………………

4. Work out the half-life of a radioactive isotope that…

(a) Starts with an activity of 20 Bq and four minutes later has a radioactivity of 5 Bq. ……………………………………………………………………………………(b) Starts with an activity of 64 Bq and 6 seconds later has a radioactivity of 4 Bq. ……………………………………………………………………………………(c) Starts with an activity of 800 Bq and nine million years later has a radioactivity of 100 Bq. ……………………………………………………………………………………5. The table below shows the change in mass number and atomic number of an atom for different types of radioactive decay.

Changes in atomic number

Changes in mass number

A -1 0B -2 -4C 0 0D +1 0Write down the letter which shows how the atomic number and mass number change for the following:

(a) emission of an alpha particle ………………………………………...(b) emission of an beta particle ………………..………………………...(c) emission of an gamma particle ……………………………………...6. Complete the following nuclear equations and circle if it is alpha or beta decay:

Th→ He+Ra24

90232 alpha / betaPu→+ Am95

24194241 alpha / betaC→ e−1

0 + ¿614 ¿ alpha / beta

Module P4: Radiation for LifeP4f: RadioisotopesThe uses of radioisotopes include tracers, smoke alarms, cancer treatment and radioactive dating. This item illustrates the use of contemporary scientific and technological developments and their benefits, drawback and risks.

GRADE G - D GRADE C GRADE B – A* Targets for Improvement

Understand why background radiation can vary.

Recall that background radiation mainly comes from rocks and cosmic rays.

Recall that some background radiation comes from waste products and man-made sources e.g. waste from:• industry• hospitals.

Evaluate the relative significance of sources of background radiation.

Recall industrial examples of the use of tracers:• to track dispersal of waste• to find leaks/blockages in underground pipes• to find the route of underground pipes.

Describe how tracers are used in industry:• radioactive material put into pipe• progress tracked with detector above ground/outside pipe• leak/blockage shown by reduction/no radioactivity after the point of blockage.

Explain why gamma radiation is used as an industrial tracer.

Recall that alpha sources are used in some smoke detectors.

Explain how a smoke detector with an alpha source works:• smoke particles hit by alpha radiation• less ionisation of air particles• current is reduced causing alarm to sound.

Recall that radioactivity can be used to date rocks.

Explain how the radioactive dating of rocks depends on the calculation of the uranium/lead ratio.

Recall that measurements from radioactive carbon can be used to find the date of old materials.

Explain how measurements of the activity of radioactive carbon can lead to an approximate age for different materials:

• the amount of Carbon-14 in the air has not changed for thousands of years• when an object dies (e.g. wood) gaseous exchange with the air stops• as the Carbon-14 in the wood decays the activity of the sample decreases• the ratio of current activity from living matter to the activity of the sample is used to calculate the age within known limits.

P4f Activities1. Outline the different sources of background radiation:

Natural Man-made

2. Alpha sources are used in some smoke detectors. Outline how smoke alarms work using the keywords smoke particles, ionisation and current in your answer.

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

3. Draw and annotate a diagram to show how gamma radiation can be used as an industrial tracer to detect leaks/blockages in pipes.

4. Radioactivity can be used to date rocks and depends on the calculation of the ratio between two elements. What are they?

……………………………… and ………………………………5. Radioactive carbon can be used to find the date of old materials.

(a) Circle the radioisotope of carbon used in dating materials.

C612 C6

13 C614 C6

15

(b) The radioisotope used in carbon dating has a half-life of 5700 years. What fraction will remain after (i) 11 400 years (ii) 17 100 years?…………………………………………………………………………………………………………………………………………………………………………(c) Outline how carbon dating works.………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………(d) What are the assumptions made?………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

Module P4: Radiation for LifeP4g: TreatmentThe concept of medical physics runs through this item. Radiations are important medicinal tools. This item looks at the use of radiations and the precautions taken to reduce the potential risks.

GRADE G - D GRADE C GRADE B – A* Targets for Improvement

Describe some similarities and differences between X-rays and gamma rays:• both are ionising electromagnetic waves• have similar wavelengths• are produced in different ways.

Recall that materials absorb some ionising radiation.

Understand how the image produced by the absorption of X-rays depends on the thickness and density of the absorbing materials.

Explain how:

• gamma rays are given out: from the nucleus of certain radioactive materials

• X-rays are made: by firing high speed electrons at metal targets

• X-rays are easier to control than gamma rays.

Recall that medical radioisotopes are produced by placing materials into a nuclear reactor.

Describe how materials can become radioactive as a result of absorbing extra neutrons.

Describe uses of nuclear radiation in medicine, to

Explain why gamma (and sometimes beta) emitters

Explain how radioactive sources are used in medicine:

include:• diagnosis• treatment of cancer using gamma rays• sterilisation of equipment.

Recall that only beta and gamma radiation can passthrough skin.

Recall that nuclear radiation can damage cells.

Describe the role of a radiographer and the safetyprecautions they must take.

can be used as tracers in the body.

Understand why medical tracers should not remain active in the body for long periods.

1. to treat cancer:• gamma rays focused on tumour• wide beam used• rotated round the patient with tumour at centre• limiting damage to non-cancerous tissue.

2. as a tracer:• beta or gamma emitter with a short half life•drunk/eaten/ingested/injected into the body• allowed to spread through the body• followed on the outside by a radiation detector.

P4g Activities1. Give two similarities between X-rays and gamma rays:

…………………………………………………………………………………..…………………………………………………………………………………..2. One difference between X-rays and gamma rays is how they are produced. Explain how they are both produced:

X-rays…………………………………………………………………………..…………………………………………………………………………………..Gamma………………………………………………………………………..…………………………………………………………………………………..3. How do you make a material become radioactive?

…………………………………………………………………………………..…………………………………………………………………………………..4. Match up the keywords to their definitions:

Ionisation

Radiation

Radioactivity

Becquerels (Bq)

Radiographer

The decomposition of the nuclei of unstable isotopes.

The name given to the person in hospitals who takes x-rays and uses radiation.

Where an atom loses or gains electrons.

The name given to the energy and particles that are released during decay.

The units that radioactivity are measured in.

5. Give three safety precautions when using radioactive materials.

……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………6. Why can gamma (and sometimes beta) but not alpha be used as a tracer in the body? How does a tracer work in the body?

…………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………7. Draw and annotate a diagram to show how gamma radiation can be used in medicine to treat cancer.

8. Give one other use of gamma radiation in medicine?

……………………………………………………………………………………

Module P4: Radiation for LifeP4h: Fission and FusionThis item deals with work on the processes of nuclear fission and fusion. Nuclear fission is a major source of energy and can be used to produce electricity. Oil and gas will become less important as supplies decrease and alternative forms of energy will be needed. This item explains the process of nuclear fission and how the energy produced can be harnessed to produce electricity. The prospect of harnessing nuclear fusion for power generation is also considered.

GRADE G - D GRADE C GRADE B – A* Targets for Improvement

Recognise that nuclear power stations use uranium as a fuel.

Describe the main stages in the production of electricity:• source of energy• used to produce steam• used to produce electricity.

Describe how domestic electricity is generated at anuclear power station:• nuclear reaction• producing heat• heating water to produce steam• spinning a turbine• driving a generator.

Describe what happens to allow uranium to release energy:

• uranium nucleus hit by neutron

• causes nucleus to split

• energy released

• more neutrons released.

Describe the process that gives out energy in a nuclear reactor as nuclear fission, and that it is kept under control.

Recall that nuclear fission

Understand how the decay of uranium starts a chain reaction.

Describe a nuclear bomb as a chain reaction that has gone

Explain what is meant by a chain reaction:• when each uranium nucleus splits more than one neutron is given out• these neutrons can cause

produces radioactive waste. out of control. further uranium nuclei to split.

Explain how scientists stop nuclear reactions going out of control:• rods placed in the reactor• to absorb some of the neutrons• allowing enough neutrons to remain to keep the process operating.

Describe the difference between fission and fusion:• fission is the splitting of nuclei• fusion is the joining of nuclei.

Describe how nuclear fusion releases energy:• fusion happens when two nuclei join together• fusion produces large amounts of heat energy• fusion happens at extremely high temperatures.

Describe why fusion for power generation is difficult:• requires extremely high temperatures• high temperatures have to be safely managed.

Understand why fusion power research is carried out as an international joint venture.

Explain how different isotopes of hydrogen can undergo fusion to form helium:

H+ H→ He23

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Understand the conditions needed for fusion to take place, to include:

• in stars, fusion happens under extremely high temperatures and pressures

• fusion bombs are started with a fission reaction which creates exceptionally high

temperatures

• for power generation exceptionally high temperatures and/or pressures are required and this combination offers (to date) safety and practical challenges.

Recall that one group of scientists have claimed to successfully achieve ‘cold fusion’.

Explain why the claims are disputed: other scientists could not repeat their findings.

Explain why the ‘cold fusion’ experiments and data have been shared between scientists.

Explain why ‘cold fusion’ is still not accepted as a realistic method of energy production.

P4h Activities1. Label and annotate each part of the diagram below to show how nuclear fuel can be used in the production of electricity.

2. Annotate the diagram below to show what happens in nuclear fission.

3. What is meant by the term “chain reaction” and why can this be potentially dangerous?

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4. How do scientists stop nuclear reactions going out of control?

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5. What is the difference between fission and fusion?

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6. How does nuclear fusion release energy? What conditions are needed?

H+ H→ He23

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These are six mark questions. You will also be assessed on the quality of your written communication (spelling,

punctuation and grammar).

The 6 mark question template (you can photocopy this page and use it to practice each of the questions)

6 marks? No problem! Just remember SSS

...

Science – write down the key words/points you will use:

Structure – Write a brief plan of the order you will write your points :1.

2.

3.

4.

5.

6.

SPAG (spelling, punctuation and grammar).

Make sure you have used full stops, commas, and other

Now you are ready to write your answer!