PHYSICS. GCE Ordinary Level (Syllabus 5052)

Transcription

1 PHYSICS GCE Ordinary Level (Syllabus 5052) CONTENTS PAGE NOTES... 1 Physics 5052 Introduction... 2 Aims... 2 Assessment Objectives... 3 Scheme of Assessment... 4 Subject... 6 Summary of Key Quantities, Symbols and Units Practical Assessment IT Usage Glossary of Terms... 26

2 NOTES Nomenclature The proposals in Signs, Symbols and Systematics (The Association for Science Education Companion to 5-16 Science, 1995) and the recommendations on terms, units and symbols in Biological Nomenclature (2000) published by the Institute of Biology, in conjunction with the ASE, will generally be adopted. Reference should be made to the joint statement on chemical nomenclature issued by the GCE boards. In particular, the traditional names sulphate, sulphite, nitrate, nitrite, sulphurous and nitrous acids will be used in question papers. It is intended that, in order to avoid difficulties arising out of the use of l as the symbol for litre, use of dm 3 in place of l or litre will be made. In chemistry, full structural formulae (displayed formulae) in answers should show in detail both the relative placing of atoms and the number of bonds between atoms. Hence -CONH 2 and -CO 2 H are not satisfactory as full structural formulae, although either of the usual symbols for the benzene ring is acceptable. Units, significant figures Candidates should be aware that misuse of units and/or significant figures, i.e. failure to quote units where necessary, the inclusion of units in quantities defined as ratios or quoting answers to an inappropriate number of significant figures, is liable to be penalised. 1

3 INTRODUCTION PHYSICS GCE ORDINARY LEVEL (Syllabus 5052) This syllabus is designed to place less emphasis on factual material and greater emphasis on the understanding and application of scientific concepts and principles. This approach has been adopted in recognition of the need for students to develop skills that will be of long-term value in an increasingly technological world rather than focusing on large quantities of factual material, which may have only short-term relevance. AIMS These are not listed in order of priority. The aims are to: 1. provide, through well-designed studies of experimental and practical Physics, a worthwhile educational experience for all students, whether or not they go on to study science beyond this level and, in particular, to enable them to acquire sufficient understanding and knowledge to 1.1 become confident citizens in a technological world, able to take or develop an informed interest in matters of scientific import; 1.2 recognise the usefulness, and limitations, of scientific method and to appreciate its applicability in other disciplines and in everyday life; 1.3 be suitably prepared and stimulated for studies beyond Ordinary Level in Physics, in applied sciences or in science-dependent vocational courses. 2. develop abilities and skills that 2.1 are relevant to the study and practice of science; 2.2 are useful in everyday life; 2.3 encourage efficient and safe practice; 2.4 encourage effective communication. 3. develop attitudes relevant to science such as 3.1 concern for accuracy and precision; 3.2 objectivity; 3.3 integrity; 3.4 enquiry; 3.5 initiative; 3.6 inventiveness. 4. stimulate interest in and care for the local and global environment. 2

4 5. promote an awareness that 5.1 the study and practice of science are co-operative and cumulative activities, and are subject to social, economic, technological, ethical and cultural influences and limitations; 5.2 the applications of science may be both beneficial and detrimental to the individual, the community and the environment; 5.3 science transcends national boundaries and that the language of science, correctly and rigorously applied, is universal; 5.4 the use of information technology (IT) is important for communications, as an aid to experiments and as a tool for the interpretation of experimental and theoretical results. ASSESSMENT OBJECTIVES A Knowledge with Understanding Students should be able to demonstrate knowledge and understanding in relation to: 1. scientific phenomena, facts, laws, definitions, concepts and theories; 2. scientific vocabulary, terminology and conventions (including symbols, quantities and units); 3. scientific instruments and apparatus, including techniques of operation and aspects of safety; 4. scientific quantities and their determination; 5. scientific and technological applications with their social, economic and environmental implications. The subject content defines the factual knowledge that candidates may be required to recall and explain. Questions testing those objectives will often begin with one of the following words: define, state, describe, explain or outline. (See the glossary of terms.) B Handling Information and Solving Problems Students should be able - in words or by using symbolic, graphical and numerical forms of presentation - to: 1. locate, select, organise and present information from a variety of sources; 2. translate information from one form to another; 3. manipulate numerical and other data; 4. use information to identify patterns, report trends and draw inferences; 5. present reasoned explanations for phenomena, patterns and relationships; 6. make predictions and propose hypotheses; 7. solve problems These assessment objectives cannot be precisely specified in the subject content because questions testing such skills may be based on information which is unfamiliar to the candidate. In answering such questions, candidates are required to use principles and concepts that are within the syllabus and apply them in a logical, reasoned or deductive manner to a novel situation. Questions testing these objectives will often begin with one of the following words: predict, suggest, calculate or determine. (See the glossary of terms.) 3

5 C Experimental Skills and Investigations Students should be able to: 1. follow a sequence of instructions; 2. use techniques, apparatus and materials; 3. make and record observations, measurements and estimates; 4. interpret and evaluate observations and experimental results; 5. plan investigations, select techniques, apparatus and materials; 6. evaluate methods and suggest possible improvements. Weighting of Assessment Objectives Theory Papers (Papers 1 and 2) A Knowledge with Understanding, approximately 60% of the marks with approximately 30% allocated to recall. B Handling Information and Solving Problems, approximately 40% of the marks. Practical Assessment (Paper 3) Paper 3 is designed to test appropriate skills in C, Experimental Skills and Investigations. In one or both of the questions in Paper 3, candidates will be expected to suggest a modification or an extension which does not need to be executed. Depending on the context in which the modification/extension element is set, the number of marks associated with this element will be in the range of 10% to 20% of the total marks available for the practical test. SCHEME OF ASSESSMENT Candidates are required to enter for Papers 1, 2 and 3. Paper Type of paper Duration Marks Weighting 1 Multiple Choice 1 h % 2 Structured and Free Response 1 h 45 min % 3 Practical test 1 h 30 min % Theory papers Paper 1 (1 h, 40 marks), Paper 2 (1 h 45 min, 80 marks), Consisting of 40 compulsory multiple choice items of the direct choice type. These questions will involve four response options. Consisting of two sections. Section A will carry 50 marks and will consist of a number of compulsory, structured questions of variable mark value. Section B will carry 30 marks and will consist of three compulsory questions. Each question will carry 10 marks. The last question will be presented in an either/or form. 4

6 Practical assessment Paper 3 (1 h 30 min, 30 marks), consisting of two compulsory 45 min practical experiment questions (15 marks each). In one or both of the questions, candidates will be expected to suggest a modification or an extension which does not need to be executed. 5

7 SUBJECT CONTENT Students should recognise and use the signs and symbols contained in `Signs, Symbols and Systematics', Association for Science Education, Reference should also be made to the summary list of symbols, units and definitions of quantities. Asterisks (*) placed alongside learning outcomes indicate areas of the syllabus where it is anticipated that teachers might use applications of information technology (IT), as appropriate. It should be appreciated that the list is not exhaustive. SECTION I: GENERAL PHYSICS 1. Physical Quantities and Units 1.1 Physical quantities 1.2 SI units 1.3 Prefixes 1.4 Scalars and vectors 1.5 Measurement of length and time (a) show understanding that all physical quantities consist of a numerical magnitude and a unit (b) recall the following base quantities and their units: mass (kg), length (m), time (s), current (A), temperature (K), amount of substance (mol) (c) use the following prefixes and their symbols to indicate decimal sub-multiples and multiples of the SI units: micro (µ), milli (m), centi (c), deci (d), kilo (k), mega (M) (d) state what is meant by scalar and vector quantities and give common examples of each (e) add two vectors to determine a resultant (a graphical method will suffice) describe how to measure a variety of lengths with appropriate accuracy by means of tapes, rules, micrometers and calipers, using a vernier as necessary (g) describe how to measure a variety of time intervals by means of clocks and stopwatches, including the period of a simple pendulum 2. Kinematics 2.1 Speed, velocity and acceleration 2.2 Graphical analysis of motion 2.3 Free-fall (a) state what is meant by speed and velocity (b) state what is meant by uniform acceleration and calculate the value of an acceleration using change in velocity / time taken (c) interpret given examples of non-uniform acceleration (d) calculate average speed using distance travelled / time taken (e) *plot and *interpret distance-time graphs and speed-time graphs 6

8 *deduce from the shape of a distance-time graph when a body is: (i) at rest (ii) moving with uniform speed (iii) moving with non-uniform speed (g) *deduce from the shape of a speed-time graph when a body is: (i) at rest (ii) moving with uniform speed (iii) moving with uniform acceleration (iv) moving with non-uniform acceleration (h) *calculate the area under a speed-time graph to determine the distance travelled for motion with uniform speed or uniform acceleration (i) state that the acceleration of free fall for a body near to the Earth is constant and is approximately 10 m/s 2 3. Dynamics 3.1 Balanced and unbalanced forces 3.2 Friction (a) describe the effect of balanced and unbalanced forces on a body (b) describe the ways in which a force may change the motion of a body (c) recall the relationship resultant force = mass x acceleration (d) *apply the relationship between resultant force, mass and acceleration to new situations or to solve related problems (e) explain the effects of friction on the motion of a body 4. Mass, Weight and Density 4.1 Mass and weight 4.2 Gravitational field and field strength 4.3 Density (a) state that mass is a measure of the amount of substance in a body (b) state that the mass of a body resists a change in the state of rest or motion of the body (c) state that a gravitational field is a region in which a mass experiences a force due to gravitational attraction (d) define gravitational field strength g as gravitational force per unit mass (e) recall the relationship weight = mass x gravitational field strength apply the relationship between weight, mass and gravitational field strength to new situations or to solve related problems (g) recall the relationship density = mass / volume (h) apply the relationship between density, mass and volume to new situations or to solve related problems 7

9 5. Turning Effect of Forces 5.1 Moments 5.2 Centre of gravity 5.3 Stability (a) describe the moment of a force in terms of its turning effect and describe everyday examples in terms of moments (b) recall the relationship moment of a force (or torque) = force x perpendicular distance from the pivot (c) apply the relationship between moment of a force, force and perpendicular distance from the pivot to new situations or to solve related problems (d) state the principle of moments for a body in equilibrium (e) apply the principle of moments to new situations or to solve related problems show understanding that the weight of a body may be taken as acting at a single point known as its centre of gravity (g) describe qualitatively the effect of the position of the centre of gravity on the stability of simple objects 6. Pressure 6.1 Pressure 6.2 Pressure changes (a) define the term pressure in terms of force and area and recall the relationship pressure = force /area (b) apply the relationship between pressure, force and area to new situations or to solve related problems (c) recall the relationship pressure due to a liquid column = height of column x density of the liquid x gravitational field strength (d) apply the relationship between pressure due to a liquid column, height of column, density of the liquid and gravitational field strength to new situations or to solve related problems (e) describe how the height of a liquid column may be used to measure the atmospheric pressure describe the use of a manometer in the measurement of pressure difference (g) describe and explain the transmission of pressure in hydraulic systems with particular reference to the hydraulic press and hydraulic brakes on vehicles (a diagram of the system is not required) (h) describe how a change in volume of a fixed mass of gas at constant temperature is caused by a change in pressure applied to the gas (i) (j) recall the relationship p 1 V 1 = p 2 V 2 (for constant temperature changes) apply the relationship between pressure and volume (for constant temperature changes) to new situations or to solve related problems 8

10 7. Energy, Work and Power 7.1 Energy conversion and conservation 7.2 Work 7.3 Power Learning Outcomes (a) show understanding that kinetic energy, elastic potential energy, gravitational potential energy and chemical potential energy are examples of different forms of energy (b) state the principle of the conservation of energy (c) apply the principle of the conservation of energy to new situations or to solve related problems (d) state that kinetic energy E k = 1 / 2 mv 2 and gravitational potential energy E p = mgh (for potential energy changes near the Earth's surface) (e) apply the relationships for kinetic energy and potential energy to new situations or to solve related problems recall the relationship work done = force x distance moved in the direction of the force (g) apply the relationship between work done, force and distance moved in the direction of the force to new situations or to solve related problems (h) recall the relationship power = work done / time taken (i) apply the relationship between power, work done and time taken to new situations or to solve related problems SECTION II: THERMAL PHYSICS 8. Kinetic Model of Matter 8.1 States of matter 8.2 Brownian motion 8.3 Molecular model (a) compare the properties of solids, liquids and gases (b) show understanding that Brownian motion provides evidence for the kinetic molecular model of matter (c) *describe qualitatively the molecular structure of solids, liquids and gases, relating their properties to the forces and distances between molecules and to the motion of the molecules (d) describe the relationship between the motion of molecules and temperature (e) explain the pressure of a gas in terms of the motion of its molecules 9

11 9. Transfer of Thermal Energy 9.1 Thermal equilibrium 9.2 Conduction 9.3 Convection 9.4 Radiation (a) show understanding that thermal energy is transferred from a region of higher temperature to a region of lower temperature (b) show understanding that regions of equal temperature are in thermal equilibrium (c) describe, in molecular terms, how energy transfer occurs in solids (d) describe, in terms of density changes, convection in fluids (e) show understanding that the energy transfer of a body by radiation does not require a material medium and that the rate of energy transfer is affected by (i) colour and texture of the surface (ii) surface temperature (iii) surface area apply the concept of thermal energy transfer to everyday applications 10. Temperature 10.1 Principles of thermometry 10.2 Liquid-in-glass thermometers (a) explain how the volume of a fixed mass of liquid may be used to define temperature scale and state examples of other such properties (b) explain the need for fixed points and state what is meant by ice point and steam point (c) discuss the structure, sensitivity, range, linearity and responsiveness of liquid-in-glass thermometers 11. Thermal Properties of Matter 11.1 Specific heat capacity 11.2 Melting, boiling and evaporation 11.3 Specific latent heat Learning outcomes (a) describe a rise in temperature of a body in terms of an increase in its internal energy (random thermal energy) (b) define the terms heat capacity and specific heat capacity (c) recall the relationship thermal energy = mass x specific heat capacity x change in temperature 10

12 (d) apply the relationship between thermal energy, mass, specific heat capacity and change in temperature to new situations or to solve related problems (e) describe melting/solidification and boiling/condensation as processes of energy transfer without a change in temperature explain the difference between boiling and evaporation (g) define the terms latent heat and specific latent heat (h) explain latent heat in terms of molecular behaviour (i) (j) recall the relationship thermal energy = mass x specific latent heat apply the relationship between thermal energy, mass and specific latent heat to new situations or to solve related problems (k) *plot and interpret a cooling curve SECTION III: WAVES 12. General Wave Properties 12.1 Describing wave motion 12.2 Wave terms 12.3 Longitudinal and transverse waves (a) describe what is meant by wave motion as illustrated by vibrations in ropes and springs and by waves in a ripple tank (b) state what is meant by the term wavefront (c) show understanding that waves transfer energy without transferring matter (d) define speed, frequency, wavelength, period and amplitude (e) recall the relationship velocity = frequency x wavelength apply the relationship between velocity, frequency and wavelength to new situations or to solve related problems (g) *compare transverse and longitudinal waves and give suitable examples of each 13. Light 13.1 Reflection of light 13.2 Refraction of light 13.3 Thin converging lenses (a) define the terms used in reflection, including normal, angle of incidence and angle of reflection (b) state that, for reflection, the angle of incidence is equal to the angle of reflection and use this principle in constructions, measurements and calculations (c) define the terms used in refraction, including angle of incidence, angle of refraction and normal 11

13 (d) recall the relationship sin i / sin r = constant (e) apply the relationship between sin i and sin r to new situations or to solve related problems define refractive index of a medium in terms of the ratio of speed of light in vacuum and in the medium (g) define the terms critical angle and total internal reflection (h) identify the main ideas in total internal reflection, apply them to the use of optical fibres in telecommunication and state the advantages of the use of optical fibres (i) (j) describe the action of a thin converging lens on a beam of light define the term focal length (k) *draw ray diagrams to illustrate the formation of real and virtual images of an object by a thin converging lens (l) define the term linear magnification (m) *draw scale diagrams to deduce the focal length needed for particular values of magnification (converging lens only) (n) describe the use of a single lens as a magnifying glass and in a projector and draw ray diagrams to show how each forms an image 14. Electromagnetic Spectrum 14.1 Properties of electromagnetic waves 14.2 Applications of electromagnetic waves (a) state that all electromagnetic waves are transverse waves that travel with the same high speed in vacuo and state the magnitude of this speed (b) describe the main components of the electromagnetic spectrum (c) discuss the role of the following components in the stated applications: (i) radiowaves in radio and television communication (ii) microwaves in satellite television and telephone (iii) infra-red waves in household electrical appliances, television controllers and intruder alarms (iv) light in optical fibres, in medical uses and telecommunications (v) ultraviolet in sunbeds, fluorescent tubes and sterilisation (vi) X-rays in hospital use and engineering applications (vii) gamma rays in medical treatment 15. Sound 15.1 Sound waves 15.2 Speed of sound 15.3 Ultrasound 12

14 (a) describe the production of sound by vibrating sources (b) describe the longitudinal nature of sound waves in terms of the processes of compression and rarefaction and deduce that: (i) a medium is required in order to transmit these waves (ii) the speed of sound differs in air, liquids and solids (c) state the approximate range of audible frequencies (d) describe a direct method for the determination of the speed of sound in air and make the necessary calculation (e) explain how the loudness and pitch of sound waves relate to amplitude and frequency describe how the reflection of sound may produce an echo (g) define ultrasound and describe one use of ultrasound, e.g. cleaning, quality control and pre-natal scanning SECTION IV: ELECTRICITY AND MAGNETISM 16. Static Electricity 16.1 Laws of electrostatics 16.2 Principles of electrostatics 16.3 Applications of electrostatics (a) show understanding that electrostatic charging by rubbing involves a transfer of electrons (b) state that there are positive and negative charges and that charge is measured in coulombs (c) state that unlike charges attract and like charges repel (d) *describe an electric field as a region in which an electric charge experiences a force (e) *draw the field of an isolated point charge and show understanding that the direction of the field lines gives the direction of the force acting on a positive test charge describe experiments to show electrostatic charging by induction (g) distinguish between electrical conductors and insulators and give typical examples of each (h) describe examples in which electrostatic charging is a potential hazard (i) describe an example of the use of electrostatic charging such as a photocopier, spraying of paint or an electrostatic precipitator 17. Current Electricity 17.1 Conventional current and electron flow 17.2 Electromotive force 17.3 Potential difference 17.4 Resistance 13

15 Learning Outcomes (a) state that current is a rate of flow of charge and that it is measured in amperes (b) distinguish between conventional current and electron flow (c) recall the relationship charge = current x time (d) apply the relationship between charge, current and time to new situations or to solve related problems (e) define electromotive force (e.m.f.) as the work done by a source in driving a unit charge around a complete circuit calculate the total e.m.f. where several sources are arranged in series (g) state that the potential difference (p.d.) across a circuit component is measured in volts (h) define the p.d. across a component in a circuit as the work done to drive a unit charge through the component (i) state the definition that resistance = p.d. / current (j) apply the relationship R = V/I to new situations or to solve related problems (k) describe an experiment to determine the resistance of a metallic conductor using a voltmeter and an ammeter, and make the necessary calculations (l) recall the relationship of the proportionality between resistance and the length and crosssectional area of a wire (m) *apply the relationship between resistance, length and cross-sectional area of a wire to new situations or to solve related problems (n) recall the formulae for the effective resistance of a number of resistors in series and in parallel (o) apply the formulae for the effective resistance of a number of resistors in series and in parallel to new situations or to solve related problems (p) *sketch and interpret the V/I characteristic graph for a metallic conductor at constant temperature and for a filament lamp 18. D.C. Circuits 18.1 Current and potential difference in circuits 18.2 Series and parallel circuits (a) *draw circuit diagrams with power sources (cell or battery), switches, lamps, resistors (fixed and variable), fuses, ammeters and voltmeters, bells, light-dependent resistors, thermistors and light-emitting diodes (b) state that the current at every point in a series circuit is the same (c) apply the principle of current in a series circuit to new situations or to solve related problems (d) state that the sum of the potential differences in a series circuit is equal to the potential difference across the whole circuit (e) apply the principle of the sum of potential differences in a series circuit to new situations or to solve related problems state that the current from the source is the sum of the currents in the separate branches of a parallel circuit 14

16 (g) apply the principle of current in a parallel circuit to new situations or to solve related problems (h) state that the potential difference across the separate branches of a parallel circuit is the same (i) (j) apply the principle of potential difference in a parallel circuit to new situations or to solve related problems apply the relevant relationships, including R = V/I and those for potential differences in series and in parallel circuits, resistors in series and in parallel, in calculations involving a whole circuit 19. Practical Electricity 19.1 Electric power and energy 19.2 Dangers of electricity 19.3 Safe use of electricity in the home (a) describe the use of the heating effect of electricity in appliances such as electric kettles, ovens and heaters (b) recall the relationships P = VI and E = VIt (c) apply the relationships for electrical power and energy to new situations or to solve related problems (d) calculate the cost of using electrical appliances where the energy unit is the kwh (e) state the hazards of using electricity in the following situations (i) damaged insulation (ii) overheating of cables (iii) damp conditions explain the use of fuses and circuit breakers in electrical circuits and of fuse ratings and circuit breaker settings (g) explain the need for earthing metal cases and for double insulation (h) state the meaning of the terms live, neutral and earth (i) (j) describe how to wire a mains plug explain why switches, fuses, and circuit breakers are wired into the live conductor 20. Magnetism 20.1 Laws of magnetism 20.2 Magnetic properties of matter 20.3 Magnetic effect of a current 20.4 Applications of the magnetic effect of a current (a) state the properties of magnets (b) describe induced magnetism (c) distinguish between magnetic and non-magnetic materials 15

17 (d) describe electrical methods of magnetisation and demagnetisation (e) describe the plotting of magnetic field lines with a compass distinguish between the properties and uses of temporary magnets (e.g. iron) and permanent magnets (e.g. steel) (g) draw the pattern of the magnetic field due to currents in straight wires and in solenoids and: (i) state the qualitative variation of the strength of the magnetic field over salient parts of the pattern (ii) state the effect on the magnetic field of changing the magnitude and/or direction of the current (h) describe the application of the magnetic effect of a current in an electric bell and a circuit breaker 21. Electromagnetism 21.1 Force on a current-carrying conductor 21.2 The d.c. motor (a) describe experiments to show the force on a current-carrying conductor, and on a beam of charged particles, in a magnetic field, including the effect of reversing (i) the current (ii) the direction of the field (b) state the relative directions of force, field and current when any two of these quantities are at right angles to each other, using Fleming's left-hand rule (c) explain how a current-carrying coil in a magnetic field experiences a turning effect and that the effect is increased by increasing (i) the number of turns on the coil, (ii) the current (d) discuss how this turning effect is used in the action of an electric motor (e) describe the action of a split-ring commutator in a two-pole, single-coil motor and the effect of winding the coil on to a soft-iron cylinder 22. Electromagnetic Induction 22.1 Principles of electromagnetic induction 22.2 The a.c. generator 22.3 The transformer Learning Outcomes (a) *deduce from Faraday's experiments on electromagnetic induction or other appropriate experiments: (i) that a changing magnetic field can induce an e.m.f. in a circuit (ii) that the direction of the induced e.m.f. opposes the change producing it (iii) the factors affecting the magnitude of the induced e.m.f. (b) describe a simple form of a.c. generator (rotating coil or rotating magnet) and the use of slip rings (where needed) 16

18 (c) *sketch a graph of voltage output against time for a simple a.c. generator (d) describe the structure and principle of operation of a simple iron-cored transformer as used for voltage transformations (e) recall the equations V p /V s = N p /N s and V p I p = V s I s (for an ideal transformer) apply the relationships between V p, V s, N p, N s, I p and I s to new situations or to solve related problems (g) describe the energy loss in cables and deduce the advantages of high voltage transmission 23. Introductory Electronics 23.1 Use of cathode-ray oscilloscope 23.2 Action and use of circuit components 23.3 Logic gates and combinations (a) describe the use of a cathode-ray oscilloscope to display waveforms and to measure p.d's and short intervals of time (detailed circuits are not required) (b) describe the action of a variable potential divider (potentiometer) (c) describe the action of thermistors and light-dependent resistors and explain their use as input transducers in potential dividers (d) state in words and in truth table form the action of the following logic gates: AND, OR, NAND, NOR and NOT (inverter) (e) recognise and draw the symbols for the logic gates listed above (American ANSI Y symbols will be used) apply the logic functions for logic gates in combination for a maximum of two inputs to solve simple logic problems SECTION V : NUCLEAR PHYSICS 24. Nucleus 24.1 Composition of a nucleus 24.2 Proton number and nucleon number 24.3 Nuclide notation (a) describe the composition of the nucleus in terms of protons and neutrons (b) define the terms proton number (atomic number) Z and nucleon number (mass number) A (c) explain the term nuclide and use the nuclide notation A Z X (d) define the term isotope and, using nuclide notation, explain how one element may have a number of isotopes 17

19 25. Radioactivity 25.1 Detection of radioactivity 25.2 Characteristics of the three types of emission 25.3 Nuclear reactions 25.4 Half-life 25.5 Uses of radioactive isotopes including safety precautions (a) name the common detectors for alpha particles, beta particles and gamma rays (structure and mode of operation of the detectors are not required) (b) *show understanding that radioactive emissions occur randomly over space and time (c) distinguish between the three kinds of emissions in terms of (i) their nature (ii) their relative ionising effects (iii) their relative penetrating powers (d) describe the deflection of radioactive emissions in electric fields and magnetic fields (e) explain what is meant by radioactive decay, using equations (involving symbols) to represent changes in the composition of the nucleus when particles are emitted discuss the existence, origin and significance of background radiation (g) explain what is meant by the term half-life (h) apply their understanding of half-life to solve simple problems which might involve information in tables or decay curves (i) describe how radioactive materials are handled, used and stored in a safe way 18

20 SUMMARY OF KEY QUANTITIES, SYMBOLS AND UNITS Students should be able to state the symbols for the following physical quantities and, where indicated, state the units in which they are measured. Students should be able to define those items indicated by an asterisk (*). Quantity Symbol Unit length l, h... km, m, cm, m area A m 2, cm 2 volume V m 3, cm 3 weight* W N* mass m, M kg, g, mg time t h, min, s, ms density* ρ g/cm 3, kg/m 3 speed* u, v km/h, m/s, cm/s acceleration* a m/s 2 acceleration of free fall g m/s 2, N/kg force* F, P... N moment of force* N m work done* W, E J*, kw h* energy E J power* P W* pressure* p, P Pa*, N/m 2 atmospheric pressure use of millibar temperature θ, t : T C: K heat capacity C J/ºC, J/K specific heat capacity* c J/(g C), J/(kg K) latent heat L J specific latent heat* l J/kg, J/g frequency* f Hz wavelength* λ m, cm focal length f m, cm angle of incidence i degree ( ) angles of reflection, refraction r degree ( ) critical angle c degree ( ) potential difference*/voltage V V*, mv current* I A, ma charge q, Q C, A s e.m.f.* E V resistance R Ώ 19

21 PRACTICAL ASSESSMENT Scientific subjects are, by their nature, experimental. It is therefore important that an assessment of a candidate's knowledge and understanding of Physics should include a component relating to practical work and experimental skills. This assessment is provided in Paper 3 as a formal practical test and is outlined in the Scheme of Assessment. Paper 3 Practical Test Introduction This paper is designed to assess a candidate's competence in those practical skills which can realistically be assessed within the context of a formal test of limited duration. The best preparation for this paper is for candidates to pursue a comprehensive course in practical Physics throughout the time during which they are being taught the theoretical content. It is not expected that all the experiments and exercises will follow the style of the Practical Test but candidates should regularly be made aware of the points Examiners look for when marking this paper (see below). The questions in the Practical Test will seek to cover most of the Objectives outlined above. In particular, candidates should be prepared to make measurements or determinations of physical quantities such as mass, length, area, volume, time, current and potential difference. Candidates should be aware of the need to take simple precautions for safety and/or accuracy. The questions will not necessarily be restricted to topics in the curriculum content. The test does not involve the use of textbooks, nor will candidates need access to their own records of laboratory work carried out during the course. Candidates will be required to follow instructions given in the question paper and to write their answers in a separate printed answer booklet. Candidates may use an electronic calculator which complies with the current version of the Regulations. Examiners assume that an electronic calculator will be used when they are setting the papers and judging the length of time required for each question. Candidates may be asked to carry out exercises based on: (a) measurements of lengths with appropriate accuracy by means of tapes, rules, micrometers and calipers, using a vernier as necessary; (b) measurements of time intervals by means of clocks and stopwatches, including the period of a simple pendulum; (c) measurements of temperature by using appropriate thermometers; (d) measurements of mass and weight by using appropriate balances; (e) measurements of the volume of a liquid or solid by using a measuring cylinder; determination of the density of a liquid, or of a regularly or irregularly shaped solid which sinks in water; (g) the principle of moments; (h) determination of the position of the centre of gravity of a plane lamina; (i) the law of reflection; (j) determination of the position and characteristics of an optical image formed by a plane mirror; (k) the refraction of light through glass blocks; (l) the principle of total internal reflection; (m) measurements of current and voltage by using appropriate ammeters and voltmeters; (n) determination of the resistance of a metallic conductor by using a voltmeter and an ammeter. This is not intended to be an exhaustive list. Reference may be made to the techniques used in these experiments in the theory papers but no detailed description of the experimental procedures will be required. 20

22 Apparatus Requirements Instructions are sent to Centres several months in advance of the date of the Practical Test. Every effort is made to minimise the cost to Centres by designing experiments around basic apparatus which should be available in most school Physics laboratories. For guidance, a list of the items used in recent papers is included at the end of this section. It is not intended to be exhaustive but should be taken as a guide to the requirements. It is intended that candidates should have 45 minutes with the apparatus for each of the two compulsory questions. Please note the requirement to provide a seating plan of each stage of the examination, as indicated on the instructions. It is essential that candidates are warned of these arrangements in advance. Spare sets of apparatus must be available to allow for breakages and malfunctions. Supervisors should check every set of apparatus before the date of the paper. Specimen results, if required, must be provided in the envelope which is sent to the Examiner containing the scripts. Apparatus 12 V, 24 W filament bulb ammeter FSD 1 A or 1.5 A beaker 100 cm 3, 250 cm 3, 1 litre Blu-tack boiling tube, 150 mm x 25 mm card connecting leads crocodile clips d.c. power supply half-metre rule lens, converging f = 15 cm low voltage (2.5 V) filament bulbs in holders masses, 50 g, 100 g measuring cylinder 100 cm 3, 250 cm 3 metre rule microscope slides mirror, plane, 50 mm x 100 mm nichrome wire 28 s.w.g (0.38 mm diameter), 30 s.w.g (0.32 mm diameter) pendulum bob pin board pivot (to fit a hole in metre rule) Plasticine protractor resistors, various retort stand, boss and clamp spring balance 0.5 N-1.0 N springs stopwatch reading to 0.1 s or better switch thermometer -10 C C (by 1 C) thread tracing paper voltmeter FSD 1 V, 5 V wooden board 21

23 General marking points Taking readings During the course of their preparation for this paper, candidates should be taught to observe the following points of good practice, which often feature in the mark scheme. A measuring instrument should be used to its full precision. Thermometers are often marked with intervals of 1 C. It is appropriate to record a reading which coincides exactly with a mark as, for example, 22.0 C, rather than as a bald 22 C. Interpolation between scale divisions should be to better than one half of a division. For example, consider a thermometer with scale divisions of 1 C. A reading of 22.3 C might best be recorded as 22.5 C, since 0.3 is nearer 0.5 than '0'. That is, where a reading lies between two scale marks, an attempt should be made to interpolate between those two marks, rather than simply rounding to the nearest mark. The length of an object measured on a rule with a centimetre and millimetre scale should be recorded as 12.0 cm rather than a bald 12 cm, if the ends of the object coincide exactly with the 0 and 12 cm marks. A measurement or calculated quantity must be accompanied by a correct unit, where appropriate. Recording readings A table of results should include, in the heading of each column, the name or symbol of the measured or calculated quantity, together with the appropriate unit. Solidus notation is expected. Each reading should be repeated, if possible, and recorded. The number of significant figures given for calculated quantities should be the same as the least number of significant figures in the raw data used. A ratio should be calculated as a decimal number, to two or three significant figures. Drawing graphs A graph should be drawn with a sharp pencil. The axes should be labelled with quantity and unit. The scales for the axes should allow the majority of the graph paper to be used in both directions and be based on sensible ratios, e.g. 2 cm on the graph paper representing 1 or 2 or 5 units of the variable (or 10, 20 or 50 etc.). Each data point should be plotted to an accuracy better than one half of one of the smallest squares on the grid. Points should be indicated by a small cross or a fine dot with a circle drawn around it. Large dots are penalised. Where a straight line is required to be drawn through the data points, Examiners expect to see an equal number of points either side of the line over its entire length. That is, points should not be seen to lie all above the line at one end, and all below the line at the other end. The gradient of a straight line should be taken by using a triangle with a hypotenuse that extends over at least half the length of the candidate's line. Data values should be read from the line to an accuracy better than one half of one of the smallest squares on the grid. The same accuracy should be used in reading off an intercept. Calculation of the gradient should be to two or three significant figures. 22

24 INFORMATION TECHNOLOGY (IT) USAGE IN O LEVEL PHYSICS (Syllabus 5052) Information Technology (IT) is a term used to cover a number of processes which have nowadays become an indispensable part of modern life. These processes are almost all based on the ability of the microprocessor chip to handle and manipulate large volumes of binary data in a short time. The use of IT is now an important factor in Physics education and it is hoped that all O Level candidates will have the opportunity to experience something of each of the following processes. 1. Data Capture (Hardware) Sensors and data loggers can be used in any experiment to measure and store a number of physical quantities which vary with time. The sensor usually converts the quantity (e.g. temperature, light/sound intensity, position, count rate, magnetic flux density) into a voltage and the data logger samples this voltage at regular intervals from a few microseconds to a few hours depending on the duration of the 'experiment'. Each sample is converted into a binary/digital number and then stored in memory. The number of samples which are taken and stored depends on the particular data logger in use but it is usually several hundred. This large number has the effect that when the stored data are subsequently plotted graphically, the data points are so close together that the physical quantity appears to vary continuously over the timescale of the experiment. Sensors and data loggers are invaluable where the timescale of the experiment is either very long (e.g. the variation of temperature over several days) or very short (e.g. the microphone signal of a handclap). Although most suppliers of sensors and data loggers will indicate the type of experiment in which they may be used, the following are some examples of their use in standard O Level Physics experiments. The variation of temperature in a latent heat demonstration The variation of induced e.m.f. in a coil as a magnet falls through it The variation of count rate in radioactive half-life measurement 2. Data Analysis (Software) The most important type of program which allows the analysis of data is the SPREADSHEET into which data may be added manually (via the keyboard) or automatically (via the data logger). These programs have a number of different functions. One of the most important uses of the spreadsheet is that it allows its data to be analysed graphically. Two or more sets of corresponding data can be plotted as histograms, as pie charts, as simple line graphs or as X-Y scattergraphs (with or without a best fit line). Once a spreadsheet has some starting point, it can calculate further data by applying a formula to the existing information. For example, if the spreadsheet started with a column of voltages and another column of corresponding currents, it could then calculate a third column of the product of the voltage and current (i.e. the power) and a fourth column of the quotient of voltage and current (i.e. the resistance). A spreadsheet allows alphanumeric and mathematical analysis of its data. For example, one column of a spreadsheet could contain the names of students in a class while neighbouring columns could contain their raw scores for the various skills in a number of assessed practicals. The program could sort the names into alphabetical order or it could calculate mean or total values or apply some scaling factor to the different scores. 23

25 A spreadsheet may also be used to build mathematical models of physical situations by calculating and plotting the necessary data. For example, the dynamic model of the two dimensional flight of a ball subject to air resistance may be examined without resorting to the calculus of sophisticated differential equations. Here, the positions of the ball after successive increments of time would be calculated algebraically and added to successive cells in the spreadsheet. These positions can then be plotted to reveal the ball's trajectory. 3. Teaching Aids and Resources (Software) There are now many software packages available which have been designed to assist the teaching of almost every topic in O Level Physics. Some of these can be used as selflearning programs for individual students to work through at their own pace while others can be used as computer generated images for classroom demonstrations and simulations. For example, Moving Molecules illustrates basic kinetic theory by allowing students to visualise what is happening to the molecules in gases, liquids and solids as temperature and pressure are changed. Although there are at present very few CD-ROMs of direct relevance to O Level Physics, this is a potential growth area and it is likely that in the near future much more use will be made of this resource. The videocassette and the laser disc are two further sources of sometimes excellent demonstrations of various topics in Physics. Certain learning outcomes of the syllabus have been marked with an asterisk (*) to indicate the possibility of the application of IT. A brief commentary on some of these outcomes follows. In some cases, software is available commercially; in others, teachers may be able to develop their own. References in the notes below are to learning outcomes. 2 KINEMATICS 2(e),, (g) and (h) offer an opportunity to use computer programs to simulate particle motion and to demonstrate how quantities such as distance, speed and acceleration are related. Data-capture techniques may also be used in practical work on kinematics. 3 DYNAMICS In (d), some examples of the application of Newton's second law may be presented through computer simulations. 8 KINETIC MODEL OF MATTER 8(c) may be effectively demonstrated using computer simulations. 11 THERMAL PROPERTIES OF MATTER In (k), data-capture techniques may be used in practical work on cooling curve graphs. 12 GENERAL WAVE PROPERTIES Comparison between transverse and longitudinal waves in (g) may be illustrated using computer simulations. 13 LIGHT Construction of ray diagrams in (k) and (m) may be effectively demonstrated using computer simulations. 16 STATIC ELECTRICITY In (d) and (e), electric field lines from point charges may be effectively demonstrated using computer simulations. 24

26 17. CURRENT ELECTRICITY 17(m) and (p) may be presented through computer simulations and data-capture. 18. D.C. CIRCUITS The analysis of circuit diagrams in (a) may be presented using computer simulation techniques. 22. ELECTROMAGNETIC INDUCTION Computer simulations, or demonstrations using a cathode-ray oscilloscope, may be used to illustrate (a) and (c). 25. RADIOACTIVITY Data-capture methods and computer simulations may be used to demonstrate the random nature of radioactive decay in (b). 25

27 GLOSSARY OF TERMS USED IN PHYSICS PAPERS It is hoped that the glossary will prove helpful to candidates as a guide, although it is not exhaustive. The glossary has been deliberately kept brief not only with respect to the number of terms included but also to the descriptions of their meanings. Candidates should appreciate that the meaning of a term must depend in part on its context. They should also note that the number of marks allocated for any part of a question is a guide to the depth of treatment required for the answer. 1. Define (the term(s)...) is intended literally. Only a formal statement or equivalent paraphrase, such as the defining equation with symbols identified, being required. 2. Explain/What is meant by... normally implies that a definition should be given, together with some relevant comment on the significance or context of the term(s) concerned, especially where two or more terms are included in the question. The amount of supplementary comment intended should be interpreted in the light of the indicated mark value. 3. State implies a concise answer with little or no supporting argument, e.g. a numerical answer that can be obtained by inspection. 4. List requires a number of points with no elaboration. Where a given number of points is specified, this should not be exceeded. 5. Describe requires candidates to state in words (using diagrams where appropriate) the main points of the topic. It is often used with reference either to particular phenomena or to particular experiments. In the former instance, the term usually implies that the answer should include reference to (visual) observations associated with the phenomena. The amount of description intended should be interpreted in the light of the indicated mark value. 6. Discuss requires candidates to give a critical account of the points involved in the topic. 7. Outline implies brevity, i.e. restricting the answer to giving essentials. 8. Predict or deduce implies that candidates are not expected to produce the required answer by recall but by making a logical connection between other pieces of information. Such information may be wholly given in the question or may depend on answers extracted in an earlier part of the question. 9. Suggest is used in two main contexts. It may either imply that there is no unique answer or that candidates are expected to apply their general knowledge to a novel situation, one that formally may not be in the syllabus. 10. Calculate is used when a numerical answer is required. In general, working should be shown. 11. Measure implies that the quantity concerned can be directly obtained from a suitable measuring instrument, e.g. length, using a rule, or angle, using a protractor. 12. Determine often implies that the quantity concerned cannot be measured directly but is obtained by calculation, substituting measured or known values of other quantities into a standard formula. 13. Show is used when an algebraic deduction has to be made to prove a given equation. It is important that the terms being used by candidates are stated explicitly. 14. Estimate implies a reasoned order of magnitude statement or calculation of the quantity concerned. Candidates should make such simplifying assumptions as may be necessary about points of principle and about the values of quantities not otherwise included in the question. 15. Sketch, when applied to graph work, implies that the shape and/or position of the curve need only be qualitatively correct. However, candidates should be aware that, depending on the context, some quantitative aspects may be looked for, e.g. passing through the origin, having an intercept, asymptote or discontinuity at a particular value. On a sketch graph, it is essential that candidates clearly indicate what is being plotted on each axis. Sketch, when applied to diagrams, implies that a simple, freehand drawing is acceptable: nevertheless, care should be taken over proportions and the clear exposition of important details. 26