Physics - Unit 1 - 10

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UNIT 2 Waves and Their Uses

Recommended Prior KnowledgePupils ought to have encountered unit I before starting this unit. In addition they will need some concept of what is meant by energy, even though it need not be defined exactly at thisstage. Pupils should be able to use a protractor and to draw simple diagrams neatly. Words such as audible, pitch, vibration, reflection, medium, vacuum, echo, timbre, pre-natal,magnification, lens and spectrum are likely to be used without being separately defined by the teacher.

ContextThis unit deals with waves and how they are used. It is to some extent an independent section of the syllabus with only a few other topics depending on it. Consequentlythose who do not wish to follow through the units in numerical order may include this unit at almost any stage.

OutlineThe unit begins by introducing the idea of wave motion in a general sense. This is an idea which though simple at one level, is in fact sometimes difficult to grasp. When sea-waves areconsidered it is unlikely that much emphasis is given to their transmission of energy and this essential aspect of waves is often neglected by pupils. The basic definitions are included andthe idea that certain quantities may be represented by an equation is worth underlining for future use. Two specific cases, sound and light, follow on from this and the fundamentalproperties of all waves are studied in the context of these two examples. The practical importance of the seemingly abstract phenomenon of refraction is illustrated by the inclusion oflenses and by their use in the correction of imperfect vision. Some of the widely varying uses of electromagnetic radiation conclude this unit.

Learning Outcomes Suggested Teaching Activities Online Resources Other resources

13(a) Describe what is meant by Energy (unit 5) transfer often involves the net movement Waves: Use ripple tanks to show

wave motion as illustrated by of matter but for wave motion it does not. Stretch a long http://www.ketterinci.edu water waves transferringvibrations in ropes and spring or rope between two pupils. One can transmit /-drussell/Demos/waves energy. A small piece of corksprings and by experiments energy to the other (make the second pupil's hand move) /wavemotion.html vibrates as the wave passes.using a ripple tank. without transferring matter. Point out the pupils' ear drums Compare with sound and

are being moved (vibrated) without the transfer of matter. Ripple tanks simulation: hearing.http://www.falstad.com/rile/

13(b) State what is meant by the A wave transfers energy through a medium without the Wavefronts: The crest line or the troughterm wavefront. medium moving as a whole. http://www.colorado.edu line is the wavefront.

/physics/2000/waves particles/waves.html

13(d) Describe transverse and Use the long spring to show transverse waves. Get the Longitudinal waves: Longitudinal waves include:longitudinal waves in such a pupils to come up with longitudinal waves. http://www.qlenbrook.kl sound,way as to illustrate the Use these terms: 2.il.us/qbssci/phys/mme ultrasound,differences between them. crest, dia/waves/lw.html seismic P-waves,

trough, shock waves.

Transverse waves


compression, http://www.bbc.co.uk/sc rarefaction,

hools/qcsebitesize/physi displacement. cslwaveslwhatarewaves

rev3.shtml13(c) Define the terms speed,

frequency, wavelength andDefine the terms. At this stage speed and velocity can betreated as essentially the same thing. Note that the

Wave formula:http://www.qcse.com/wa

Use the formula to deducethe speed of radio waves

amplitude and do calculations frequency is the number of waves (not complete waves) yes/wave speed.htm from the publishedusingvelocity= frequency xwavelength.

passing a point in unit time. Frequency is not necessarilyan integer. Deduce the formula.

Wave parts:http://id. mind.net/-zona/

wavelength and frequency ofa local station.

mstm/physics/waves/partsOfAWave/waveParts. htm#wavelenqth

13(e) Describe the use of a rippletank to show

Show these experimentally if not in a ripple tank then in atray of water. Draw diagrams of waves entering a shallow

Ripple tank reflection:http://www.crocodile-

Comparison: caterpillar-tracked vehicles cannot steer.

(1) reflection at a plane (slower) region at an angle. Show where the waves would clips.com/absorb/AP4/s By slowing down one tracksurface, have reached if the original medium had continued and ample/DJFPhO66.html and speeding up the other the(2) refraction due to achange of speed at

then where the waves actually are. They have skewedaround as one side slows before the other.

or:http://www.open.ac.uk/s

vehicle skews round likewaves refracting. Similarly

constant frequency. cience/infocus/ripple.ht soldiers marching shoulder-to-shoulder, come to groundwhere they travel slower.

16(a) Describe the production of

sound by a vibrating source.

Consider:

a tuning fork,

Production of sound:

http://teacher.scholastic.

Place small particles on a

drum or loudspeaker. a viol in (or local stringed musical instrument), com/ lessonrepro/lesson a drum, plans/profbooks/sound.h vibrating rulers, cardboard strips held in the spokes of a bicyclewheel,

or:http://www.cilenbrook.kl

loudspeaker

2. il.us/cibssci/phvs/mme

a other examples.Pupils should feel the vibrations.

dia/waves/tfl.htmlGuitar strings:http://www.qlenbrook.kl2. il.us/cibssci/phys/mmedia/waves/qsl. html


16(

c) State the approximate rangeof audible frequencies.

Use a loudspeaker and a signal generator to test thefrequency range of the pupils' hearing.

Sound and the ear:http://www.plenbrook.kl

The actual frequency rangevaries from person to person

2.il.us/qbssci/phys/mme but a standard range of 20 -*dia/waves/edl.html 20 000 Hz is usually taken for

a person of normal hearing.16(g) Explain how the loudness and

pitch of sound waves relate toUse a microphone and CR0. to show how the tracevaries with frequency and with amplitude. Relate these

Loudness:http:Ilgcsephysics.comlp

amplitude and frequency. observations to pitch and loudness. wav9.htm16(b) Describe the longitudinal

nature of sound waves andUse the vibrations of a loudspeaker to explain that thevibration direction is parallel to that of the sound wave.

Sound waves:http://www.qlenbrook.kl

describe compression and Compare this with a long spring or trolleys joined by 2.il.us/cibssci/phys/Classrarefaction. springs. /sound/u1 a.html

16(d) Explain why a medium isrequired in order to transmit

Show the bell-jar experiment if at all possible; the dangercan be seen striking the bell but little or no sound is heard.

Bell jar experiment:http://www.gcse.com/wa

Consider: the Sun can beseen but not heard,

sound waves and describe anexperiment to demonstratethis.

ves/sound2.htm astronauts communicate inspace using radio (or bytouching helmets).

13(f) Describe simple experimentsto show the reflection and

Demonstrate an echo from the front of a large building orcliff (-lOOm away if possible). This can be extended to

Speed of sound:http://www.sv.vt.edu/cla

Refraction in sound can bedemonstrated/described

refraction of sound waves, measure the speed of sound - use two blocks of wood to sses/ESM4714/Student using a beach-ball fil led withmake a short, distinct clap or a loud whistle or a high- ProI/class95/physics/sp CO2. This can act as a sound

pitched feedback sound from a megaphone. Measure thedistance with rulers, rope or a pedometer. Clapping in timewith the echo from a closer wall (30m) allows the timetaken for the sound to travel to the wall and back to be

eed.htmlReflection in sound:http://www.physics.lsa.u

lens (later in this unit) and beused to focus sound (lenseswork by refraction). If filledwith He, it would be a

measured more accurately. mich.edu/demolab/demo diverging lens..asp?id=871Refraction in sound:http://tonydude.net/physics2Ol/p201 chapter3.ht

ml

Learni

ng Outcomes Suggested Teaching Activities Online Resources Other resources

16(h) Describe how the reflection of Refer to methods involving firing guns or simply observingsound may produce an echo. someone claps the two pieces of wood together from a

few kilometres away (these rely on the speed of lightbeing very much larger indeed than that of sound).

16(e) Describe a di rect method for Sound travels much faster in sol ids and liquids. When a Speed of sound inthe determination of the hammer str ikes a long length of metal rai lings, two sounds materials:speed of sound in air and are heard: one through the rai lings; one through the air . http://www.glenbrook.klmake the necessary 2. il.uslgbsscilphyslClass

calculation. /sound/ul ll2c.html16(f) State the order of magnitude Quote speed of sound values for air, liquids and gases.

of the speeds of sound in air,liquids and solids.

16(i) Describe the factors which Emphasise that the same note played on different Timbre:influence the quality (timbre) instruments differ only in the shape of the trace on a http://www.open2.net/soof sound waves and how CR0. not in their periodic t imes. Show this using musical undofl ife/prog pages/sothese factors may be instruments, a microphone and a CR0. Show that the undslife/viewer/object/57demonstrated using a CR0. amplitude does not affect the shape of the trace. I 6.html

16(j) Define ultra sound. Define ultra sound and give a variety of uses: Uses of ultrasound: Bats use ultra sound to formcleaning sensitive artefacts, http://www.google.co.uk/ a picture of their

16(k) Describe the uses of ultra quality control, pre-natal scanning, search?ci=Uses+of+ultra surroundings. Dogs can hearsound in cleaning, quality distance measurers (dataloggers in sound&btnG=Search&hl ultra sound (dog whistles).control and pre-natal universities/schools).scanning. or:

http://www.bbc.co.uk/sc

hools/gcsebitesize/physics/waves/sound ultrasoundandseismicwavesrev4.shtml

14(a) Define the terms used in These topics are best covered experimentally; pupils mayreflection including normal, use mirrors and ray-boxes, torches or (optical) pins.angle of incidence and angleof reflection.

Learni


14(b) Describe an experiment to The law may be modelled in 3D using rods or rulers to Law of reflection:illustrate the law of reflection. represent the rays and the normal and the desk top to act http://www.qlenbrook.kl

as a mirror. 2. il.us/cibssci/phys/mmedia/optics/lr. html

14(d) State that for reflection, the Observe that there are many rays for which the angle of Diffuse and regularangle of incidence is equal to ref lection equals the angle of incidence but the correct one reflection:the angle of ref lection and lies in the same plane as the normal and the incident ray. http://www.qlenbrook.kluse this in constructions, Emphasise that all angles are measured between the ray 2.il.us/qbssci/phys/Class

measurements and and the normal. /refln/ul3lld.htmlcalculations.

14(c) Describe an experiment to Emphasise that an image is the location from which the Plane mirror images: Consider more complicatedfind the position and light seems to come. It has not actually travelled behind http://www.glenbrook.kl examples such as two mirrorscharacteristics of an optical the mirror. An eye or a photographic plate placed at the 2.il.us/qbssci/phys/mme at right-angles or aimage formed by a plane image position would not detect anything. For a mirror dia/optics/ifpm.html kaleidoscope.mirror. hanging on a wall, the image may well be in the next room

or building and someone there would not be able to seethe person standing in front of the mirror.

14(e) Define the terms used in Show some simple examples of refraction: the bent stick, Refer back to the skewingrefraction including angle of apparent reduction in depth, heat haze, pass a ray of light round of caterpillar trackedincidence, angle of refraction into a tank containing two liquids of different densities - a vehicles when the tracks areand refractive index, very small amount of paint in the liquids will scatter light driven at different speeds.

so that the path of the ray may be seen.14(f) Describe experiments to Carry out experiments with a glass block and a ray-box, Refraction: Emphasise that as the light

show refraction of light torch or a slit in a blind/curtain or (optical) pins. http://www.cilenbrook.kl leaves the second face of athrough glass blocks. 2.il.us/qbssci/phys/Class rectangular block, it reverses

/ref rn/u 1411d.html the procedure which occurredat the first and emergesparallel to the incident ray.

14(g) Do calculations using the Measure i and r. Plot i -* r. Calculate sin(i) and sin(r). Reflection andequation Plot sin(i) -* sin(r). Measure the gradient. Calculate refraction:sini/sinr= constant. sin(i)/sin(r). State that using the gradient gives more http://www.phy.ntnu.edu

emphasis to those points nearest to the average .tw/iava/Iiciht/flash Light. hbehaviour. Averaging the values of sin(i)/sin(r) does not. tml

Learni


14(i) Describe experiments to Explain that when a ray emerges f rom glass into air, the Total internal reflection: Pass a ray into the curvedshow total internal reflection. emergent angle is larger than the angle at which it strikes http://www.phy.ntnu.edu face of a semi-circular glass

the surface. In due course, it emerges at 900 to the lower .tw/iava/liqhtlflashLiqht.h block, into the side face of aface. If the angle at which it strikes the surface increases, tml glass block or a tank of water.then the emergent angle exceeds 90 and it passes back Move the ray. There comes ainto the glass. This is reflection not refraction. Refraction point at which no light at allout of the glass is now impossible. emerges through the surface.

14(h) Define the terms critical angle Emphasise the fact that two conditions must be met Fish-eye view:

and total internal reflection. before T.l.R. can occur: http://www.phy.ntnu.edu The light must pass from the slow to the fast medium. .tw/Iava/fishEye/fishEye. The angle at the surface must exceed the critical !ituiangle.

Retroreflectors:http://users.ipfw.edu/masters/Graphics/AM/Refraction.html#TIR

14(j) Describe the use of optical Optical fibres rely on T.l.R. Digital pulses (light/no light) Optical fibres: There are transoceanicfibres in telecommunications transmit the information. Advantages include: more http://www.bbc.co.uk/sc optical fibre cables and it isand state the advantages of information can be sent per second (many phone calls on hools/qcsebitesize/physi possible to have an opticaltheir use. one line), less prone to interference, less easy to tap into, cs/waves/reflectionrefra link straight into a personal

fewer repeaters. Optical fibres need to be sheathed to ctionanddiffractionrev5.s computer or telephone.prevent light passing from one fibre into the next. htn

14(k) Describe the action of thin Pass a ray of light from a ray-box or torch into a lens Converging lenses:

lenses (both converging and (ideally curved in only one dimension) and observe the http://www.cilenbrook.kldiverging) on a beam of light, path of rays at different distances from the centre. This is 2.il.uslgbsscilphys/Class

difficult to do with optical pins. /refrn/ul4l5da.html14(l) Define the term focal length. Pass a beam of parallel rays into a lens and observe the

convergence. Define focal length.14(m) Draw ray diagrams to Emphasise three types of ray: Image formation: (1) These three special rays

illustrate the formation of real (1) Incident, paraxial rays refract through the focal point. http://www.cilenbrook.kl are not the only ones toand virtual images of an (2) Incident rays striking the optical centre emerge 2.il.us/qbssci/physlClass originate from the objectobject by a lens. undeviated. /refrn/ul4l5da.html point, but all the others

(3) Incident rays which pass through or seem to have also meet at or seem topassed through the focal point emerge paraxially. have come from the same

Learni


image point.(2) It is usual to use the toppoint of an object as theobject point but everyother point on the objectalso produces an image.

14(n) Define the term linear Scale diagrams will only be accurate i f drawn carefully.magnification and draw scale Start with the object and the lens and find the image or

diagrams to determine the start with the object and the image and find the focalfocal length needed for points.particular values ofmagnification (converginglens only).

14(o) Describe the use of a single Pupils can be given incomplete or unlabelled diagrams Magnifying glass: It is helpful if pupils havelens as a magnifying glass and instructed to complete them. Pupils should know the http:I lwww.physics.pom seen these devices operatingand in a camera, projector position of the object relative to the principal focus in the ona.edu/sixideas/labs/L or partially dismantled. Makeand photographic enlarger different devices. RM/LRO7.pdf a large model of the cameraand draw ray diagrams to /enlarger using a cardboardshow how each forms an Camera: box and an appropriate lens.image. http://science.howstuffw

orks.com/cameral.htmEnlarger:http://en.wikipedia.org/wiki/Enlarger

14(p) Draw ray diagrams to show A model eye can be made from a fish bowl or a round- The eye:

the formation of images in the bottomed flask with a lens held to the outside with a ring of http://www.cilenbrook.klnormal eye, a short-sighted modelling clay. Fill the bowl or flask with water and a very 2.il.us/qbssci/phys/Classeye and a long-sighted eye. small amount of paint to scatter the light. Pass light into /ref rn/u1416a.html

the model eye.14(q) Describe the correction of Explain the causes of both short- and long-sightedness Short sight:

short-sight and long-sight, and describe the way in which lenses are used to solve http:/ /www.ci lenbrook.klthe problems. 2.il.us/cibssci/phys/Class

/refrn/ul 416e.html


Long sigh

t:http://www.qlenbrook.kl2. il.us/gbssci/phys/Class

/refrn/ul 4l6d.html

15(a) Describe the dispersion of Best shown in practice using a glass/water prism and a Prisms:l ight as i llustrated by the ray-box, torch or sli t in a bl ind/curtain. Light is spli t up http:/ /webphysics.ph.msaction on l ight of a glass according to its wavelength. state.edu/iavamirror/ipmj

prism. /iava/dispprizm/index.html15(b) State the colours of the This leads to the traditional seven colours of the Rainbows:

spectrum and explain how the spectrum/rainbow. The higher the frequency, the greater http://www.phy.ntnu.educolours are related to the extent of the refraction. "Violet refracts violently" or .tw/iava/Rainbow/rainbofrequency/wavelength. "blue bends best". Use an infra-red detector (e.g. a w.html

thermometer with bulb blackened) to detect radiation or:beyond the red end of the visible spectrum and show that http://eo.ucar.edu/rainbosome sections of the spectrum cannot be detected by the ws/human eye.

15(c) State that all electromagnetic List properties shared by all electromagnetic radiations, Some pupils will point out thatwaves travel with the same include: light cannot be a wave as ithigh speed in air and state speed in air, does not require a medium.the magnitude of that speed. transverse nature, One might point out that

travel in vacuum, magnetic and electric fieldsdo pass through a vacuumand that light is an oscillation

of such fields.15(d) Describe the main Emphasise that the boundaries between regions are The electromagnetic

components of the arbitrary and conventional - a snake or an insect have spectrum:electromagnetic spectrum. different end wavelengths for their visible regions. http://www.phy.ntnu.edu

.tw/Iava/em Wave/em Wave.html

15(e) Discuss the role of the Emphasise that electromagnetic wave properties change Applications of I.R:following components in the gradually as the frequency changes. http:Ilwww.ebs-stated appl icat ions: Avoid referring to "The seven types of electromagnetic thermociraphy.com/cialle(1) radiowaves: radio and radiation". ry/index e.html

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televisioncommunications, This topic provides ideal material for pupil projects. The The electromagnetic(2) microwaves: satellite pupils can research these areas themselves and then talk spectrum:television and telephone, to the rest of the class about what they have found. There http://imagine.gsfc.nasa(3) inf ra-red: household is a huge amount of information publ ished on the internet qov/docs/science/knowelectrical appliances, and the difficulty is likely to be keeping it accurate and ll/emspectrum.htmltelevision controllers and relevant, or:intruder alarms, http://www.electro-

(4) light: optical fibres in optical.com/bbrad/emsmedical uses and pect.htmtelephone,(5) ultra-violet: sunbeds,fluorescent tubes andsterilisation,(6) X-rays: hospital use andengineering applications,(7) gamma rays: their use inmedical treatment.
http://thermociraphy.com/ciallehttp://optical.com/bbhttp://optical.com/bbhttp://thermociraphy.com/ciallehttp://optical.com/bbhttp://optical.com/bbhttp://optical.com/bbhttp://thermociraphy.com/ciallehttp://optical.com/bbhttp://thermociraphy.com/ciallehttp://optical.com/bbhttp://thermociraphy.com/ciallehttp://optical.com/bbhttp://optical.com/bbhttp://thermociraphy.com/ciallehttp://optical.com/bb

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UNIT 3 Atoms and Radioactivity

Recommended Prior Knowledge

Pupils will have heard about atoms and electrons but are very unlikely to have a very clear idea of what they are. It would be helpful if pupils had already encountered atoms asbuilding-bricks in chemistry and had some conception of just how small they are. Similarly, pupils will have met electric charge in more domestic circumstances but thisquantity is not properly encountered until the next unit and teachers should be aware that, for pupils, it is not necessarily a fully understood branch of the subject. Element,ionising and random are words which might well be used freely by the teacher whilst remaining something of a mystery to the pupils. The word radioactive will have beenencountered mostly in negative and dangerous contexts. Furthermore, some pupils will not realise that the Sun is just an ordinary star and this ought to be stated specifically inthe final sections.

Context

This unit deals with the structure of ordinary matter and as a result it presents ideas which are vital in many scientific contexts ranging from engineering and materials scienceto pharmacology. The ideas included will be fundamental to many other sections of the syllabus and if the numerical order of units is not followed, the first parts of this unitmust be dealt with at an early stage.

Outline

The first half of this unit describes the structure of an atom and the evidence for the nuclear theory. Pupils learn about the three constituent particles which make up atoms andtheir arrangement within it. Terms like isotope will be explained. The second half deals with radioactivity and the properties of alpha-, beta- and gammaradiation. The fission oflarge atoms and the fusion of hydrogen atoms in stars will be explained and, then, some elementary mathematics is needed for the definition of half-life and is used incalculations.

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27(a) Describe the structure of the Pupils have probably heard of atoms and that there are Electrons: Electrons occur in:atom in terms of nucleus and roughly 90 different types which combine to make all http://www.sciencemuseum.or electrical conduction inelectrons. substances. They have probably heard about electrons. ci.uklon-line/electron/index.asp gases and electrical

State that these particles are small objects which carry and thermal conductionnegative charge. They are important in: ionisation Atomic Structure: in metals (unit 5). Some(chemistry), electrostatics (unit 4), current electricity (unit http://www.purchon.com/chemi of these effects are4), electrolysis (chemistry), beta-emission (26(a)) and stry/atoms.htm found in all substances.thermionic emission (unit 10). There are electrons in all Electrons areatoms. fundamental particles.

27(b) Describe how the Geiger- Describe the experiment. Three possible results: Geiger-Marsden Experiment: Emphasise the extremeMarsden alpha scattering (1) Nearly all alpha particles pass straight through. The http://www.schoolscience.co.u inequality in theexperiment provides evidence atom is almost entirely empty space. klcontentl4/physics/particles/p distribution of matterfor the nuclear atom. (2) A few particles are deflected through noticeable articlesdiscover2.html within the atom.

angles. There is something in the foil. -99.95% of the mass is(3) A very few particles rebound through very large Nucleus: concentrated in 1012angles. There is something in the foil which is very www.physicslab.co.uk % of the volume. Use asmall, very dense and repels alpha particles (positive), local comparison, e.g.
http://www.purchon.com/chemihttp://www.purchon.com/chemi

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a pea in a local footballstadium.

27(c) Describe the composition of Since the electrons are negative and easy to remove The nuclear atom: The helium nucleus isthe nucleus in terms of (electrostatics, ionisation, thermionic emission), they must http://www.lancs.ac.ukluq/coo four times moreprotons and neutrons. be in the outer orbits and keep atoms apart. The nucleus kedl/rutherford.htm massive than that of

is the dense and positive centre of the atom. State that the hydrogen but has onlynucleus is made up of positive and neutral particles of twice the charge. Thevery similar mass. These are protons and neutrons. neutral particles

keeping the two protonsapart also have mass.

27(d) Def ine the terms proton The proton number determines the number of e lectrons innumber (atomic number), Z the neutral atom and so it determines the chemicaland nucleon number (mass properties of that substance. It is the atomic number.number), A. All carbon atoms have 6 protons and all atoms with 6

protons are carbon and so on. The nucleon numberdetermines the mass of the nucleus and is sometimescalled the mass number. Avoid the term "neutron number".

27(f) Define the term isotope. Two atoms with the same proton number may have a Isotopes: Emphasise that thedifferent number of neutrons. They have the same http://www.southwest.com.au/ proton number alonechemical properties but are not identical. They are -ifuller/chemistrv/isotopes.htm determines thedifferent isotopes of the same atom. or: chemical properties

http://hyperphysics.phy-'2C and 13 C are

astr.cisu.edu/hbase/nuclear/nu identicalchemically (or

cnot.html use another example).27(g) Explain, using nuclide

12C and 13 C are bothnotation, how one element isotopes of carbon.may have a number of Use the nuclideisotopes. notation here before

radioactivity ismentioned.

26(k) Describe how radioactive Explain dangers of nuclear radiation, include: burns, Radioactive safety: Emphasise that alpha-,materials are handled, used sickness, biological cell damage, cancer, cell mutation. http://www.cicse.com/radio/saf beta- and gamma-and stored in a safe way. Rules include: use the minimum activity, keep your ety.htm radiation do not make
http://www.lancs.ac.ukluq/coohttp://astr.cisu.edu/hbase/nuclear/nuhttp://www.cicse.com/radio/safhttp://www.lancs.ac.ukluq/coohttp://astr.cisu.edu/hbase/nuclear/nuhttp://www.cicse.com/radio/saf

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distance, and insert protective layers. It is essential to other materialsstate the rules and to obey them. radioactive when they

are absorbed.26(a) Describe the detection of Where possible, bring radioactive samples near to a GM Detecting Radiation: State that some

alpha-particles, beta-particles tube or a spark counter. Use an old, luminous watch or http://www.bbc.co.uk/schools/ substances cause theand gamma-rays by altimeter or suitable rocks i f educat ional samples are not c icsebitesize/phys ics/ radioact iv exposure of nearbyappropriate methods. available. Such substances are emitting something. The ity/detectinqradiationrev2.shtm photographic plates -

radiations can also be detected by a variety of devices. I this was howOnly one method of detection needs to be learnt by the radioactivity waspupils. discovered. Describe

the tracks in a cloudchamber.

26(c) State for radioactive Where possible use a mixed source and show that there Radiation properties: Tabulate the propertiesemissions, their nature, are three types of emission which have distinct properties: http://www.physics.isu.edu/rad of the three types ofrelative ionising effects and (1) heavily ionising but easily absorbed, inf/properties.htm radiation. Include:relative penetrating powers. (2) less ionising but less easily absorbed, particle/wave,

(3) weakly ionising but difficult to absorb completely. charge, mass, ionising strength, penetrationstrength, nature, behaviour in

electric andmagnetic fields.

26(d) Describe the deflection ofradioactive emissions inelectric fields and magneticfields.

26(b) State and explain the random Measure the count-rate from a source (background Random emission: Life assurance worksemission of radioactivity in radiation will do). Notice that it varies about an average http://www.physicsdaily.com/p on a similar basis.direction and time. value. Emphasise that whilst random events are utterly hysics/Random Individual deaths are

unpredictable individually, on a sufficiently large scale, the unpredictable but with abehaviour is very accurately predictable (half-life ideas or: large enough number of
http://www.bbc.co.uk/schools/http://www.physics.isu.edu/radhttp://www.physicsdaily.com/phttp://www.bbc.co.uk/schools/http://www.physics.isu.edu/radhttp://www.physicsdaily.com/p

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lead pupils to imagine that the number of atoms falls in http://serc.carleton.edu/guants customers, the likelysome manner such as this: 160 -* 80 -* 40 -* 20 -* 10 -* kills/activities/PennyDecay.htm number of deaths in awhat happens now? With numbers this small, of course, I given time varies verythe behaviour is unpredictable). little.

26(e) Explain what is meant by Pupils should know that radioactive decay is the random Radioactive decay: Consider only two typesradioactive decay. emission of alpha-, beta- or gamma-radiation from http:Ilwww.walter- of radioactive decay:

unstable nuclei. The emissions are unaffected by fendt.de/ph11e/lawdecay.htm alpha and beta. Then

temperature, pressure and chemical combination, explain that these mayRadioactive series: occur on their own, orhttp://www.walter- with gamma.fendt.de/ph 11 e/decayseries.ht

27(e) Explain the term nuclide and When explaining this notation, make it clear that the Nuclide notation: Emphasise that afteruse the notation X to element X determines what the number Z is and vice http://www.iqhs.ed in.sch.uklm the emission of an

versa. E.g. if Z = 7, then X is always an N (nitrogen). athscience/chemistrynotes/topi alpha- or beta-particle,construct equations whereradioactive decay leads to The equation for the alpha decay of, say, 238 U is fairly c3.html the nucleus maychanges in the composition of straightforward. Emphasise that in beta emission a rearrange itself and

emit an electromagneticthe nucleus, nuclear reaction occurs first: n -* p + e. Hence, the wave (gamma-ray). No

superscript and subscript, in e, are present to balance particle is emitted.the equation. A beta-particle is not made of -1 proton. Notation such as

confuses pupils.26(f)1 Explain the processes of State that 236 U is explosively radioactive. Bombarding Fission: The chain reaction can

fission. 92 http:Ilhyperphysics.phy- be modelled with a23592 j with neutrons may produce this isotope which may

astr.qsu.edu/hbase/nucene/fis vertical array of

lead to a chain reaction. Do not explain fission and fusion sion.html horizontal matches.together. The terms are very similar but the processes Light the lowest matchare essentially the reverse of each other. but it is too far away

from the ones above toignite them. If a secondarray of matchesinterpenetrates the first,distances are reducedand they can all ignitefrom the bottom
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upwards26(g) Describe with the aid of a A nuclear power station is l ike a standard steam turbine Nuclear power stations:

block diagram one type of station powered by coal, oil or gas. It is simply that the http://www.nucleartourist.comfission reactor for use in a mechanism for boiling the water is different.power station.

26(m) Discuss the origins and effect Measure the count-rate in the laboratory. It is never zero. Background radiat ion: Pupils find it di ff icult toof background radiation. Two sources: http://www.darvill.clara.net/nuc understand that risky

natural background radiation - rocks and space rad/sources.htm procedures are used in manmade exposure - medical diagnosis (include X- or: hospitals until it israys but emphasise that they are not nuclear in http://www.ansto.ciov.au/edu/n pointed out that mostorigin), medical treatment, power stat ions, mil itary uclear age/nuclear age biol.h medical procedurestests, flying, travel to areas with higher levels and so tm involve some risk buton. that the treatment is

There are small risks with all levels of exposure and the less hazardous than therisk increases with the absorbed dose. Even the highest disease.natural levels seem to pose few health risks.

26(i) Explain what is meant by the Quote a specific example: 1 kg of 238j contains -2.5x1 02492

Half-life: Emphasise that the

term half-life. 7 .atoms and has an activity of-1.2x10 Bq. 2 kg made of

http://hyperphysics.phy- constant time for

astr.gsu.edu/hbase/nuclear/hal halving does not-5.OxlO atoms and has an activity of-2.4x10 Bq etc. fli.html depend on the start

Therefore A a N. Draw the graph of N -* t. As the value or: point. It also takes oneof N falls so does the rate at which it is falling. This graph http://www.bbc.co.uk/schools/ half-life to fall from 80%has the familiar property of halving in a certain constant gcsebitesize/physics/radioactiv to 40% or from 96% totime. ity/radioactivedecayandhalflifer 48%. Consequently in

evi.shtml half-life experiments,the clock can be startedat any convenientvalue.

26(j) Make calculations based on Carry out a standard school laboratory determination of Half-life calculations: Plot height o f water in ahalf-life which might involve half-life or show videos/DVDs of such experiments. Pupils http://www.darvill.clara.net/nuc burette -* time afterinformation in tables or shown plot the graph and calculate the answer. Paint one face of rad/hlife.htm opening tap (this doesby decay curves, a large number of small cubes a distinct colour. Model not give a particularly

decay by throwing the cubes from a beaker on to the desk good curve but theand removing those which land with the painted face height does decreaseupwards. Repeat many times. Plot number of cubes left -* at a decreasing rate).number of the throw. Carry out calculations. Only use
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whole numbers of half-lives but problems which require abackground count correction should be included. Half-livesencompass a very wide range of values: billions of yearsto milliseconds

26(l) Discuss the way in which the There are many examples but these include: Uses of radiation: There are so manytype of radiation emitted and Alpha emitters are used to deliver radiation locally in http://www.bbc.co.uk/schools/ examples that it isthe half-life determine the use medical procedures (e.g. to a tumour inside the brain) qcsebitesize/physics/radioactiv important to make itfor the material, and in smoke detectors. ity/radioactivedecayandhalflifer clear why a certain

Beta emitters are used when determining the evi.shtml procedure needs thethickness of paper as it is manufactured and the level particular properties of of fruit juice in a carton. the radiation chosen Gamma emitters are used when radiation has to and why the othersleave the human body to be detected for diagnosis or would not be effective.when treating internal organs from outside. The half-life must be long enough for the procedure to beaccurate but not so long that is constitutes a healthhazard.

26(n) Discuss the dating of objects Emphasise that 14C is continuously produced in the upper Radiocarbon dating: The process has to beby the use of 14C. and

intohttp:/ /www.c14datinq.com corrected for

atmosphereliving things throughpasses

photosynthesis and digestion; it only occurs in things fluctuations in thewhich were once alive including: wood, bones, seeds. prevailing level of 14 C.Pupils can be unsure about which things wereonce alive.

This is done usingthe

Its half-live is -5730y and after about 20000y,the dating

tree rings ofancient

is less accurate as little 14 C is left. redwood trees -dendrochronology.

26(1)2

Explain the processes of Emphasise that the Sun and all stars have burnt for too Nuclear fusion: Emphasise that both

fusion. long and given off too much energy for their power source http://www.iet.efda.org/paqes/ the fusion of smallto be chemical. It is now known that it is powered by four content/fusion i html nuclei and the fission of hydrogen atoms merging into one helium atom. This or: large ones releaseprocess is highly exothermic. Pupils should know that H + http://en.wikipedia.org/wiki/Nu energy. A different ruleH -* He + energy clear fusion applies at the two ends

of the periodic table.

26(h) Discuss theories of star Stars are formed when clouds of gas and dust collapse Star formation:formation and their energy under gravity, the temperature increases until the http:I lwww.qcse.comleblstarl .production by fusion. hydrogen nuclei can fuse. Stars are in balance when the htm

pressure caused by the fusion reaction balances that
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UNIT 4 Moving Charges


Pupils will need to have encountered electrons and should know where they are to be found in the atom. Pupils are likely to have some basic understanding of electrostatic charging and this will beuseful in coming to grips with electric charge in a more general manner. That charge comes in two distinct types which may cancel out is also worth explaining as, frequently, it is just assumed to betrue. It would be useful if pupils had encountered the idea of electric current in some domestic or more elementary way before it is properly defined here.

Context

This very substantial unit is an absolutely essential preliminary for the topics which are met in units 7 and 10. Electricity is a major constituent of any physics course and it is here that the mostfundamental ideas are initially explained. Pupils do not find these ideas easy or self-evident and so this unit needs to be tackled with particular care.

Outline

The early sections deal with electrostatic charge and some situations in which it is found. The fundamental link between charge and electrons is made explicit at this stage. The electric field can betreated as another field of force and the idea of force lines can be introduced quite naturally with it. The distinction between conductors and insulators is drawn and this leads directly into therelationship between charge and current. The ampere is defined in some imprecise way at this point. This opens up the topic of electrical circuits and all the fundamental ideas follow from the concept ofan electric current. E.m.f. and p.d. are introduced, and power and resistance are defined here. Pupils will also become very familiar with circuit diagrams and the symbols for many essential conductingcomponents. This is a large and important unit and it should not be rushed.


18(a) Describe experiments to Use a rubbed, insulating rod to deflect a trickle of water, Theatre of Electricity: Use a Van de Graaf show electrostatic charging make hair stand on end, pick up dust and small pieces of http:Ilwww.mos.orcilslnltoelt generator to showby friction, paper. Rub a balloon and it sticks to the wall. oe.html electrostatic effects. This

high voltage deviceRecall that clothing sticks to your back on dry days, that Van de Graaf Generator: must only be used by awalking on nylon carpets, leaving cars and touching TV http://www.howstuffworks.co qualified operator andscreens causes small electric shocks. A tinglingsensation

m/vdg.htm under conditions of the

is felt before lightning storms. strictest safety.Use local examples with which the pupil will be familiar asclimate has an effect.

18(d) State that unlike charges These effects are most easily shown by balancing The Gold-Leaf Electroscope: Use a gold-leaf

attract and that like charges charged rods on a lens or watch glass. http://www.glenbrook.k12.il. electroscope to showrepel. us/qbssci/phys/mmedia/esta repulsion of the leaf.

tics/esn.html
http://current.e.m.f.and/http://current.e.m.f.and/

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18(c) State that there are positive Use several different charged rods. There are only two Types of Charge: Set up a series circuitand negative charges and types of behaviour and only two types of charge. http://www.bbc.co.uk/school with an EHT supply, twothat charge is measured in s/cicsebitesize/physics/electr separated metal platescoulombs. Use two rods of different materials together to show a icity/electriccharqeandcurren and a very sensitive

reduced effect. trev4.shtml galvano-meter orcoulombmeter.

One type of charge cancels the other and so they may becalled positive and negative. A table-tennis ball (with a

conducting coating)

shuttles between the twoplates and a reading isrecorded.The high voltage EHTsupply must only beused by a qualifiedoperator and underconditions of thestrictest safety.

18(b) Explain that charging of solids State this as a fact. Pupils have probably heard of Charging by friction: A can containing a dusterinvolves a movement of electrons (even if unit 3 has not been taught) and know http://www.plenbrook. k12.il. is on a gold-leaf electrons. they are negative. us/qbssci/phys/Class/estatic electroscope. Take a

s/u812a.html nylon rod from the canEmphasise that the negative charges move and that which rubs against thepositive objects have lost electrons. duster. The leaf deflects.

Reinsert the rod. Thedeflection collapses.

18(e) Describe an electric field as a Emphasise the idea that actions occur near to a charged Electric field:

region in which an electric object: pick up small pieces of paper, dust on polished http://hyperphysics.phy-charge experiences a force. glass, clothing sticks to back, and crackling near overhead astr.cisu.edu/hbase/electric/

power cables. elefie.html18(f) State the direction of lines of Plot field patterns with EHT supply, electrodes and Plotting field patterns: Pupils can become adept

force and describe simple semolina grains in cooking oil. The high voltage EHT http://www.physicslab.co.ukl at drawing electrostaticfield patterns, supply must only be used by a qualified operator and Efield.htm fields.

under conditions of the strictest safety. Electric Fields: Give them a few rules:http://www.colorado.edu/phy Field lines do not cross.

Avoid comparing electric and magnetic fields at this early sics/2000/waves particles/w 9 Field line leave
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stage, it confuses. avpart3.html conductors at rightangles. Arrows point from + to -

Try: ball to ball, plate toplate, ball to plate, cloudto city skyline/trees/cars.

18(g) Describe the separation of Two metal balls on insulating stands are touching. Bring a Electrostatic Induction:charges by induction, rod near to one ball. Separate the balls and check the http://www.physics.ncsu.edu

charges using a gold-leaf electroscope. Charge a gold- /courses/py208/2O8animatioleaf electroscope itself by induction. ns/induction.html18(h) Describe the dif ferences Use a low voltage d.c . c ircuit with a lamp to test common Conductors and insulators: Not ice that wood does

between electrical conductors materials. http://www.ndt- not conduct a current butand insulators and state ed.orci/EducationResources/ does discharge anexamples of each. Try to discharge a gold-leaf electroscope through these HighSchool/E lectricity/condu electroscope. Never use

common materials. Can the charge pass through people? ctorsinsulators.htm a wooden object toDo not try to pass electric currents throughpeople.

rescue someone whoisbeing electrocuted.

Pupils will see that the best conductors aremetals.

18(i) State what is meant by Standing on a rubber sheet or plastic bag andrepeat.

"earthing" a chargedobject.

18(j) Describe examples where Spark hazard: Lightning: Conductors solvethese

charging could be a problem (1) On oil tankers sailors wear special conducting http://www.fi.edu/weather/lici problems, e.g.e.g. lightning, shoes. htning/lightninci.html slightly conducting

(2) Aeroplanes and filling station tanks are electrically aeroplane tyresconnected to the tanker when being filled with fuel. discharge landing(3) Small shocks in cars or large carpeted shops. planes slowly

lightning conductors.18(k) Describe examples where Explain how these devices work. Pupils can be given Photocopier:

charging is helpful e.g. sheets with printed diagrams of different stages in the http://home.maine.rr.com/raphotocopier and electrostatic procedure and can label or complete them. ndylinscott/copier. htmprecipitator.

Concentrate on the charge placed on the photosensitive Electrostatic Precipitator:
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drum surface and how light enables it to be removed. http://www.eas.asu.edu/-holbert/wise/electrostaticprecip.

In a photocopier, a mirror image is formed twice which htnrestores the original pattern. This is an interestingoccurrence in its own right . Use as the image something Elect rostati c Spraying:which lacks left/right and top/bottom symmetry, e.g. a http://www.spraytec.com/artilarge letter F, L or R. cles/Electrostatic.htm

or:http://en.wikibooks.org/wiku

Uses of static electricity %28GCSE science%29

19(a) State that a current is a flow Refer to the shuttling ball experiment. Set up a series Electric Current:of charge and that current is circuit with an ammeter, large resistance and a http://hyperphysics.phy-measured in amperes. coulombmeter. Plot charge -* time. astr.cisu.edu/hbase/electric/

Use a larger current. elecur.html

or:Emphasise that a current is a " loop flow" of charge which http://www.sunblock99.orci.uis the mechanism for energy (not properly defined unti l k /sb99/people/DMackay/eleunit 6) transfer. The bicycle chain is a reasonably good ctricity.htmlanalogy for a current. Use the word current rather than or:amperage. http://www.schoolscience.co

u k/content/3/physics/circu its/circhl pci3.html

20(b) State that the current at every Allow pupils to predict how current varies at differentpoint in a series circuit is the places in a series circuit.same, and use this in

calculations. Then allow them to test their predictions.20(d) State that the current from the Measure the current in different branches of parallelsource is the sum of the circuits. Currents spli t but the total remains the same.cur rents in the separate Change the resis tance of some branches.branches of a parallel circuit.

Compare with water in supply pipes.
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19(b) Do calculations using the At this stage it is easier to define the ampere as the Current and charge: Explain that a chargedequation coulomb/second rather than the more accurate reverse. http://www.bbc.co.uk/school battery stores a certaincharge = current x time. s/gcsebitesize/physics/electr amount of charge. It can

Some pupils find rearranging equations hard, even though icity/electriccharqeandcurren supply 20A for 2 h or I OAin more everyday examples - e.g. 50 krrvli for 2 h, trev5.shtml for 4 h etc. A flat batterydistance travelled = 100 km - there seems to be no cannot supply charge.problem.

19(c) Describe the use of an This will be covered as pupils use ammeters in different Using a multimeter:ammeter with different experiments. Pupils should know how to use the http://www.doctronics.co.uk/

ranges. ammeters they deal with. meter.htm19(d) Explain that electromotive First explain that e.m.f. is the property of a source of Definition of electrical Heat water in a

force (e.m.f.) is measured by electrical energy, include: cells, generators. If a circuit is quantities: polystyrene cup with athe energy dissipated by a lef t on for twice as long it transfers twice as much energy http://monopole.ph.gmw.ac. low voltage (this word issource in driving a unit (unit 5). Hence energy/charge is a constant. uk/-thomas/emf/handout6.P hard to avoid) immersioncharge around a complete DF heater. Plot temperaturecircuit. -* time; this is equivalent

to energy -* charge.19(e) State that e.m.f. is work There are a variety of analogies possible for this difficult E.m.f and p.d: Coal lorries travel in a

done/charge. idea: The Coulomb Brothers carry sacks of joules around http://www.patana.ac.th/pare continuous loop from thethe c ircuit. They drop the joules of f at the appliance and nts /cur ri cu lum/Phys ics K4/u coal mine to the powerreturn with an empty sack. nits/DJFPhO35.html station and travel back

empty. There is a fixedamount of energy perlorry.

19(f) State that the volt is given by There is a fixed number of joules/coulomb.J/C.

19(g) Calculate the total e.m.f. Carry out the measurement with a voltmeter. Consider Cells in series and parallel:where several sources are car batteries (6 x 2.OV) and PP9s (6 x 1.5V). Keep a PP9 http://www.batter yuniversity.arranged in series and which has been sawn in half and show the six layers. com/partone-24.htmdiscuss how this is used inthe design of batteries.
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19(h) Discuss the advantage of Refer back to 20(d). Charge up a model lead-acid cell for Several cells in para llel:making a battery from several a few minutes. Discharge it through a torch lamp and time http://www.al laboutcircuits.cequal voltage sources of how long it takes. om/vol 6/chpt 3/3.htmle.m.f. arranged in parallel.

Repeat with two lead cells in parallel, each of which wascharged for the same time and with the same current asthe previous cell.

19(i) State that the potential This can be done by referring back to the definition of Potential difference:difference across a circuit e.m.f. The p.d. however, is concerned with where the http://www.reqentsprep.org/

component is measured in energy ends up, not where it comes from. Reqents/physics/phys03/apvolts. otdif/default.htm

19(j) State that the p.d. across acomponent in a circuit isgiven by the work done in thecomponent/charge passedthrough the component.

19(k) Describe the use of a Pupils learn how to use the meters to which they have Using a multimeter:voltmeter with different access by carrying out their own experiments. http://www.doctronics.co.uk/ranges. meter.htm

19(l) State that resistance = Ohm's Law:p.d./current and use the http://www.walter-equation fendt.de/ph11 e/ohmslaw.htresistance = voltage/current ff1in calculations.

19(m) Describe an experiment to Perform the experiment for a metal/carbon conductor, plot Current and voltage:measure the resistance of a V -* I. Measure the gradient. State "This is a 50V/A http://iersey.uoregon.edu/vla

metallic conductor using a conductor" or whatever it is. b/Voltacie/voltmeter and an ammeterand make the necessary Repeat with other values and plot on the same axes.calculations. "These are 20V/A or 10 V/A conductors." This value tells

us how hard it is to send a current through the conductor.The 50V/A is offers more resistance than the IOV/A.Resistance is measured in WA - also called the ohm, 0.
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19(q) Describe the effect of Plot V - I for a tungsten filament bulb. Why is it not a Temperature dependence of Use an ohmmeter totemperature increase on the straight line? resistance: measure the resistance of resistance of a resistor and a http://www.patana.ac.thlpare a small low voltage bulbfilament lamp and draw the Why is it harder to send a current through the filament nts/curriculum/Physics K4/u (e.g. 6V) heated up in arespective sketch graphs of when it is hot (temperature is not covered until unit 6 but nits/DJFPhO35.html water bath or sprayedcurrent/voltage, pupils are likely to be aware of elementary kinetic theory)? with a cooling spray.

It requires a little time forthe bulbs filament toreach any temperature

outside.19(n) Discuss the temperature When filament bulbs blow, why is it when they arel imitations on Ohm's Law. switched on? The current surge occurs because the

resistance is low when they are switched on.19(o) Use quantitatively the Plot V - I for wires of different lengths and compare Dependence on length and Use conducting putty

proportionality between gradients. Or use an ohmmeter. Use a poor conductor area: which can be extrudedresis tance and the length and with a signif icant resi stance for a short length. Plot R -* x. http:/ /www.reqentsprep.org/ into cylinders of dif ferentthe cross-sectional area of a Repeat for different cross-sectional areas. Reqents/physics/physO3/bre cross-sectional areas andwire. sist/default.htm different lengths.

19(p) Calculate the net effect of a Plot V - I for parallel and series combinations. Resistors in parallel and Measure the resistance of number of resistors in series Emphasise: series: networks made of nand parallel. "A thick wire is just many thin ones laid side by side" http://schools.matter.org.uk/ parallel branches of n

"A long wire is just many short ones laid end toend"

Content/Resistors/Default.ht resistors. How hot do the

rn resistors get?19(r) Describe the operation of a Measure R at different light intensities for an L.D.R. It is LDRs:

light-dependent resistor. difficult to measure the intensity easily or accurately but http://www.doctronics.co.uk/l

def inite fractions of a standard intensity can be use by dr sensors.htmlett ing the light pass through a variable aperture, e.g. cut or:ever bigger holes in a piece of cardboard. http://www.antonine-

education.co.uk/PhysicsA2/Options/Module 9/Topic 6/TOPIC 6.HTM

20(a) Draw circuit diagrams with: These symbols are best learnt gradually in the course of Circuit symbols: Rectifying diodes do notpower sources (cell, battery describing experiments or when pupils write them up. It is http://www.gcse.com/circuit feature largely elsewhereor a.c. mains), not a good idea to produce a sheet containing all the symbols.htm in this syllabus and it
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switches (closed and open), symbols at the beginning of this section; this generates might be sensible toresistors (fixed andvariable),

confusion. investigate their

light dependent resistors, conductioncharacteristics

lamps, The teacher might, however, keep a record of the symbols at this point.ammeters, encountered by the pupils as the course progresses andvoltmeters, give out a full sheet when they have all been encounteredmagnetising coils, separately.bells,fuses,

relays,light emitting diodes,rectifying diodes.

20(c) State that the sum of the Reminder: p.d. is concerned with where the energy ends P.d.s in series:potential di fferences in a up. Consider two resistors (AB and BC) in ser ies. The http://www.sec.org.za/physicseries circuit is the equal to energy which ends up between terminal A and C (i.e. in s/plOelpd.htmlthe potential difference the two resistors) is equal to that which ends up betweenacross the whole circuit and A and B added to that between B and C.use this in calculations.

Set up a series circuit and demonstrate this. Use theopportunity to include a section of circuit with resistors inparallel. Note these resistors all have the full p.d. of thatsection of the circuit across them which only counts oncewhen finding the total p.d. across the circuit.

20(e) Do calculations on the whole Pupils will need to practise answering questions starting Resistance:circuit, recalling and using with simple circuits (one cell, one ammeter and one http://hyperphysics.phy-formulae including R = VII resistor) and gradually try more complicated arrangements astr.cisu.edu/hbase/electric/rand those for potential as they become more proficient. esis.html

differences in series, resistorsin series and resistors inparallel.

UNIT 5 Energy and Energy Sources


Most pupils will have some concept of energy in a general industrial or domestic sense but they are less likely to be as precise in their understanding as the subject demands atthis level. An elementary experience of the distinctions between the different forms of energy would be useful even at the start of this unit.
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Context

Since energy is one of the fundamental ideas which underpin the whole of this subject, this is another fundamental unit. In the first section, however, one can afford to swimwith the tide and leave the idea of energy less than properly defined. It does lead into the full and fundamental definition, however, and at that point more care will be neededas the concepts and definitions are used throughout the rest of the course.

Outline

At first, the fairly gentle topic of energy transformation and energy sources is dealt with. There are few difficult or abstract ideas here and it lends itself to a less mathematicaltreatment than many other areas. It is desirable, however, to keep the subject as precise as possible and to make sure that pupils do not start using terms like power, energyand force interchangeably. It is essential that when energy is properly defined in the second half of this unit, it is done carefully and that its structural importance as a conceptis thoroughly emphasised. The terms kinetic and potential energy can be used quantitatively and the definition of work is included. Efficiency and power can be fully definedhere, even if they have featured in previous units. The formula, E = mc2, will excite some pupils who will believe that they are now real physicists - encourage them. Finally theenvironmental consequences of power generation will return them to more straightforward and familiar areas.


8(a) List the different forms of It is probably best to name and describe the different forms Types of energy:energy with examples in of energy as they occur in the course rather than to list them http://www.cicse.com/enerciy/twhich each form occurs. in an somewhat abstract and artificial way all at once. At ypes.htm

some point, however, it makes sense to list the energy forms or:

which have been encountered and to ensure that pupils can http://powermin.nic.in/kids/typidentify which form of energy is most important in a given es of enerqy.htmchange. Energy cannot be properly defined until work donehas been defined (later in this unit), but most pupils will havesome idea of what energy means here.

8(b) State the principle of the Consider some particular examples of energy change. Conservation of energy:conservation of energy and http://www.irish-apply this principle to the What energy changes occur in a hydroelectric power station? enerqy.ie/content/content.aspconversion of energy from What energy changes occur when electrical energy is used ?section id=1 I 35&lanpuacieone form to another. domestically in the cooker? ki=1

An electric drill?A mobile telephone charger? Energy transformations:What energy changes occur in a motor vehicle? http://www.physicsclassroom.When it is going up hill? As it accelerates? com/mmedia/enerqy/pe.htmlWhat energy changes occur in a nuclear power stat ion? or:
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http://www.nottinqhamschools

co.uk/eduweb/schools/school

s-template. aspx?id=8748(d) List renewable and non- This can be quite an arid topic if taught conventionally, but it Non-renewable energy Emphasise that the Sun

renewable energy sources. does lend itself to project work. sources: is the ultimate source of http://www.sustainableenerqy most energy consumed

.gld.edu.au/sources/nonrene on Earth but that this iswable.html not true of geothermal

energy, nuclear energyRenewable energy sources: and tidal energy.http://www.sustainableenerqy.cild.edu.au/sources/renewable. htmlor:http://www.factmonster.com/ipka/A0907040. html

8(e) Describe the processes by Pupils might research the whole topic individually or a smallwhich energy is converted group of pupils might research one type of renewable energyfrom one form to another, and then explain their findings to the whole class.including reference to

It is important that pupils remember that this is a physics chemical/fuel energy (a project and they should make clear the origins of the energyregrouping of atoms) source as well as any environmental benefits, e.g. hydrogen hydroelectric generation is not a source of renewable energy since it has to be(emphasising the generated by some means.mechanical energiesinvolved) What is the pupil proposing as the source of the energy to solar energy (nuclei of generate it? Pupils should understand that renewableatoms in the Sun) energy does not mean that it can be "used again", rather that nuclear energy it is being renewed as it is used so that it will "not run out". geothermal energy wind energy.

8(j) Calculate work done from the Emphasise the difference between doing work and getting Work done: The formula mgh comesformula work = force x tired. http://www.qlenbrook.k12.il.us from force x distance.distance moved in the line of /qbssci/phys/Class/enerqy/u5l
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action of the force. A human gets tired supporting a weight at a constant height laa.html Doing work is the sameeven though no work is being done. Likewise no work is as transferring energydone against gravity when a suitcase is moved horizontally. Mechanical energy: and energy is the ability

http://www.bbc.co.uk/schools/ to do work.Give many examples including: li fting a load vert ically gcsebites ize/physics/enerqy/pupwards , rolling a barrel up a plank at an angle, removing an otent ia landkinetic revl.shtml The two quanti ties areelectron from an atom, excited nuclei rearranging themselves inextricably intertwined.after radioactive decay (gamma-radiation). This is true quantitatively

and so they have the

same unit.8(c) State that kinetic energy The formula %mv2 can be deduced from F = ma and a = (v2- Kinetic energy:Ek = %mv2 and that potential u2)/2. It is usually better just to state it at this stage. http://hyperphysics.phy-energy E = mgh and use astr.qsu.edu/hbase/ke.htmlthese equations in Potential energy:calculations. http://www.cilenbrook.kl2.il us

/qbssci/phys/Class/enerqy/u5lI b.html

8(k) Calcu late the eff iciency of anenergy conversion using theformula efficiency= energyconverted to the requiredform/total energy input.

8(h) Describe the process of Emphasise that every energy conversion generates someelectrici ty generation and heat which is usually lost to the surroundings.draw a block diagram of theprocess from fuel input to Try to discourage pupils from writing, " lost as heat, lightelectricity output. and sound". Few systems waste energy as ligh t and those

which do lose energy as sound, lose very little whencompared to the quantity lost as heat.

8(l) Discuss the efficiency of Figures on energy input and output are usually available from Power station efficiency:energy conversions in a local power s tation and th is may even be a convenient http://www.aie.org.au/melb/mcommon use, particularly place in the course to arrange a visit. aterial/resource/pwr-eff.htm
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those giving electricaloutput.

or:

A discussion of power station efficiency might include more http://www.memaqazine.org/beff icient systems including combined power and heat ackissues/aprO2/features/sixt(C.P.H.) ypc/sixtypc.html

8(m) Discuss the usefulness of energy output from a numberof energy conversions.

8(n) Calculate the power from the This definition gives a specific meaning to power which is Work and power:formula distinct from energy. Power is always: the rate of change of http://www.physicsclassroom.

power= work done/time something measured in joules. Give examples: the rate of com/Class/enerqy/U5LIa.htmtaken. doing work, the rate of losing heat, the rate of generatingenergy, etc.

8(f) Explain nuclear fusion and These two opposite processes both release energy but Energy in fission and fusion:fission in terms of energy emphasise that fusion only releases energy for small nucle i http:I lwww.energyguest.ca.goreleasing processes. and fission for large ones. Quote the accurate masses of the vlstorylchapterl 3.html

proton, neutron and helium nucleus and show that mHe < 2m

+ 2mm.

8(g) Do calculations using the Consider a few specific examples of fission such as:mass-energy equation:E=mc2. 2

92 0 U+ n -1Ba+ 12 Kr +3n 56 36 0

8(i) Discuss the environmental Start a class discussion. Groups put forward the merits of Environmental issues:issues associated with power bui ld ing a part icular sort of power stat ion for their http://www.qcse.com/energyl

generation. country/community. climate change.htm

Pupils concentrate on the negative aspects of power

generation: global-warming, pollution, radioactive discharges,and health effects.They should be reminded of the importance of an adequatepower supply.

UNIT 6Thermal Energy and Matter


Pupils should have encountered some basic ideas concerning heat and temperature and the difference between them needs to be made clear e.g. a spark has a hightemperature but can emit only a little thermal energy whilst the polar sea is cold but the internal energy of all its molecules is large. Many pupils will not distinguish between
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electrical and thermal conduction and will, also, need to be put straight. Pupils will need to know terms like insulation and radiation (applied to l.R. radiation). Someelementary kinetic theory is also needed for this unit.

Context

This unit introduces the topic of thermodynamics - another hugely significant area of physics. Many large industries rely on its being understood. This unit could be fittedinto a course almost anywhere since it is, to some extent, independent of many of the concepts on which the other units rely. Energy, however, ought to have been properlydefined before it is taught. Heat is often referred to as thermal energy.

Outline

The early ideas of conduction and convection are fairly easy to explain and to understand and many pupils will already be aware of these two energy transmissionmechanisms. Radiation is likely to prove harder and it is worth ensuring that pupils have a clear understanding of this topic before moving on. The effective insulation ofbuildings is dealt with and the manner in which a thermometer functions will be introduced here. Pupils will meet these phenomena: expansion, boiling, melting andevaporation. The definitions of heat capacity, specific heat capacity and specific latent heat are included in this unit.


9(a) Describe how to distinguish There are many simple examples. Stir hot tea with plastic, There are several types of between good and bad wooden, glass, aluminium, stainless steel and silver simple equipment whichconductors of heat. spoons/rods. show comparative thermal

conduction properties.Poke a fire with iron, brass and copper rods.Give practical examples: a saucepan should be madefrom a good conductor whilst its handle is made from apoor one. There are many others.

9(b) Describe in molecular terms Use a model of a solid structure (balls joined by springs) Heat transfer: Pupils can be linkedhow heat transfer occurs in and show that shaking one end leads to vibrations at the http://www.lanly.com/heatinq.h together in a line using theirsolids, other. tm arms and vibrations can be

or: sent along the line.In a metal, a vibrating atom can propel electrons a very http://www.mansfieldct.org/sch Compare metalliclong distance at high speed. They collide with other ools/mms/staff/hand/convcond conduction with kicking aatoms far off and set them vibrating. This is a much faster rad.htm football the entire length of process. or: the pitch.

http://sol.sci.uop.edu/-ifalward
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/heattransfer/heattransfer htmlThermal conduction:http://phunphysics.virqinia.edu/topics/thermal.html

9(c) Describe convection in fluids Use a Bunsen burner to heat a beaker of water at one Illustrate convection within terms of density changes. side, on the bottom. The convection current can be seen specific examples:

using a few tiny crystals of potassium permanganate at windthe bottom. heat transmitted around a

roomSpecial tubes which link back on themselves in a square the ice-box in ashape can be used to illustrate convection, refrigerator cools the area

below it.There is a clear series of events which take place inconvection: hot water expands -* its density falls -* itrises - it pushes away the liquid above it and sucks in theliquid next to it -* a circulation is set up.

9(d) Describe the process of heat Hot objects emit I.R. radiation (unit 6). The hotter the IR radiation: Examples include:transfer by radiation. object, the more radiation it emits. At equilibrium, an http://www.pcse.com/enerpy/r energy from Sun to

object absorbs just as much as it emits. adiation.htm Earthor: electric fires (not

Be careful to distinguish between absorption and http://k12.ocs.ou.edu/teachers/ radiators)emission. Absorption experiment: set up a black can of reference/overrad.html thermal imaging.water and a white can of water in direct sunl ight. Absorption/emission:Determine the temperature rises. http://sol.sci.uop.edu/-ifalward Trick question: Why are

/physicsl 7/chapter7/chapter7. polar bears white?Wear a black T-shirt and a white one in direct sunlight. t!Pii Answer: Camouflage.What happens? Emission experiment: set up the twocans filled with boiling water in the shade. Record thetemperature drop with time.
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9(e) Describe how to distinguishbetween good and bademitters and good and badabsorbers of infra-redradiation.

9(f) Describe how heat is Simple experiments measuring the temperature drop of atransferred to or from can of water , a warm piece of metal , or even abuildings and to or from a thermometer itself, lagged in different ways or given a thin

room. black coating from a sooty candle can be used to illustratethe processes.

9(g) State and explain the use of The poor conductivity of air does not itself explain Insulation: A few insulation techniquesimportant practical methods insulation, as most buildings are surrounded by many http://www.sei. ie!content!conte are not designed toof heat insulation for metres of air. nt.asp?section id=1 111 suppress convection. Whybuildings. is white a popular colour for

Most heat is transferred to or from buildings and rooms by houses in hot countries?convection in the air. The principle of most insulation Consider the day and themechanisms is to suppress convection, night.

This is done by trapping the air. It is then important thatair is a poor conductor of heat.

10(a) Explain how a physical Make it clear that the property chosen must change Thermometric parameters: Mention the:property which varies with significantly, measurably and always in the same direction http://www.cartaqe.org.lb/enlth volume of mercury!temperature may be used for (prevents ambiguity). Any property which behaves in this emes/Sciences/Physics/Therm ethanol,the measurement of way this will do. odynamics/AboutTemperature! resistance of platinum,temperature and state Development!Development.ht thermoelectric e.m.f. of aexamples of such properties. fli thermocouple.

10(b) Explain the need for fixed Two points are needed to draw a straight line and two Fixed points: Emphasise that the icepoints and state what is fixed points are needed to specify exactly every particular, http://honolulu.hawaii.edu/dist point is the onlymeant by the ice point and intermediate point. ance!scil22!Proprams!p20!p2 temperature at which icethe steam point. O.html#4.%2OTemperature%2 and water can co-exist and

Give some idea of how they are obtained in practice. OScales the steam point is the onlyCalibrate a thermometer on which no scale has been temperature at which watermarked (use rubber bands or a permanent pen to mark and steam may co-exist -the fixed points), or check a laboratory thermometer. both at standard

atmospheric pressure.
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10(d) Describe the structure and Let pupils see a variety of liquid-in-glass thermometers Thermometers: Describe and show aaction of l iquid-in-glass with different ranges and sensitivities. http://honolulu.hawaii.edu/dist thermocouple. Discuss itsthermometers (including ance/sci I 22IProqramsIp2OIp2 advantages andclinical) and of a Get them to expla in why one thermometer has a greater 0.html#4.%20Temperature%2 disadvantages. Will itsthermocouple thermometer, range than another or why the graduations on one OScales readings (between 0C andshowing an appreciation of its thermometer are closer than on another. 100C) agree with hose onuse for measuring high Thermocouples: the liquid-in-glasstemperatures and those Let them see that the bulbs have different volumes, the http://www.efunda.com/desiqn thermometer? Use a

which vary rapidly . bores are dif ferent, the lengths are dif ferent and the l iquids standards/sensors /thermocou thermocouple to observemight well be different. Will these thermometers be ples/thmcple intro.cfm the cooling of a beaker of linear? How were the points marked on the scale? hot water.

10(c) Discuss sensitivity, range and Consider the difficulty of reading a temperature when the Range and sensitivity:linearity of thermometers. thermometer is in someone's mouth. How can this be http://kr.cs.ait.ac.th/-radoklphy

solved? sics/j7.htmHow would the pupils design a clinical thermometer - onethat maintains its maximum reading?

11(a) Describe a rise in State the increasing speed of the molecules as the Kinetic theory:temperature of a body in temperature rises as a fact but try to justify it, e.g. as http://www.bcpl.netl-kdrews/kterms of an increase in its temperature rises: mt/kmt.htmlinternal energy (random or:thermal energy). Brown ian motion becomes more violent, http://www.falstad.com/qasl

chemical reactions speed up, the speed of sound in gases rises.

11(b) Define the terms heat Emphasise that a rise in temperature is a consequence of Heat capacity: Emphasise that heatcapacity and specific heat the transfer of thermal energy (cause and effect). http://www.westqa.edu/-chem/ capacity is measured for acapacity. courses/chem 1211 d/lecture/C particular object whereas

Heat and temperature are not the same thing. hapter6/sldOO8.htm specific heat capacity is theSpecific heat capacity: property of a substance.

Heat water in a beaker with an immersion heater or use http://hyperphysics.phy- Specific heat capacity dealsan electric kettle. astr.cisu.edu/hbase/thermo/sp with temperature changes

ht.html and it unit includes that of temperature
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11(c) Calculate the heat transferred Plot AT -* t (temperature rise -* time). The initial straightusing the formula thermal line reveals that AT a Q (heat supplied) since Q = Pt.energy = mass x specific heat Kettles often have a rated power marked on them.capacity x change intemperature. Using this value, determine the specific heat capacity of

water.

11(d) Describe melting/solidification Cool a test-tube of molten wax and plot T- t. Melting and boiling: Specific heat capacity isand boiling/condensation in http://stweb.peel.edu.on.ca/ss defined for a single phase

terms of energy transfer Notice the shape of the graph and where the wax sweb/SNCI D/Edmatters/Gr9 I changing temperaturewithout a change of becomes solid. Do not melt candle wax or any other ntroduction/Handouts/Chemist whilst melting and boilingtemperature. inflammable substance with or near a naked flame. ry/Chanqes%2Oof%2OState.ht are phase changes

occurring at a singleMeasure the temperature of water as it is brought to the temperature.boil and keep measuring it as it boils.

11(e) State the meaning of melting Define melting point and boiling point.point and boiling point.

11(f) Explain the difference Leave various dishes of water in direct sunlight. Record Evaporation and boiling: See 12(e) and 12(g) in unitbetween boiling and their maximum temperature. Do they ever reach 100C? http://hyperphysics.phy- 9.evaporation. Tabulate the differences between the two terms. astr.cisu.edu/hbase/kinetic/vap

pre.html#c211(h) Explain latent heat in terms of Explain that melting/boiling involves pulling the molecules Vaporisation:

molecular behaviour. apart against an attractive force which is holding the http://en.wikipedia.orWwiki/Evamolecules together. porationUse a few small balls held together by doubled-sidedsticky tape or adhesive strips. Energy is needed to

Physics - Unit 1 - 10

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