Welcome to our Diploma Class.
I hope you found the introduction helpfull.
Our first topic will be Physics and Physics Measurements.
I hope you will access the notes from the class wiki before we begin.
All the Best.
Mr. G
Monday, August 30, 2010
Tuesday, November 10, 2009
Photo Electricity Task
You are provided with the simulation set up from Phet.
Analyze the effect of the radiation falling on different metals
1. Cooper
2. Zinc
3. Sodium
4. Platinum
5. Calcium
Collect data
The analysis will be on the effect of the intensity as well as wavelength.
Write a brief conclusion on the analysis.
Analyze the effect of the radiation falling on different metals
1. Cooper
2. Zinc
3. Sodium
4. Platinum
5. Calcium
Collect data
The analysis will be on the effect of the intensity as well as wavelength.
Write a brief conclusion on the analysis.
Thursday, October 29, 2009
Project Work
Dear Students
For the Energy project the assessment will be on the notes/hand out you will give during the presentation and the presentation itself.
Please check the worksheet I sent for update for the assessment areas they are all indicated in the second page. The scaling is pent stratified meaning 1-5 with 5 as the most appropriate, satisfactory, or adequate
Another area of assessment will be in the planning
The grid below must be used as a planning log
Name _________________________ Topic ________________________________________ Time__________________
Planning LOG
Date
Time(hrs)
What was done
Resources
Total time
Types of resources
Gioko Anthony
For the Energy project the assessment will be on the notes/hand out you will give during the presentation and the presentation itself.
Please check the worksheet I sent for update for the assessment areas they are all indicated in the second page. The scaling is pent stratified meaning 1-5 with 5 as the most appropriate, satisfactory, or adequate
Another area of assessment will be in the planning
The grid below must be used as a planning log
Name _________________________ Topic ________________________________________ Time__________________
Planning LOG
Date
Time(hrs)
What was done
Resources
Total time
Types of resources
Gioko Anthony
The Syllabus
TOPIC TM OBJECTIVES
The realm of physics
( SL + HL ) 1 To understand range of magnitudes of quantities in our , universe order of magnitude, ranges of magnitude of distances, masses and times that occur in the universe, from smallest to greatest., differences of orders of magnitude.
Measurement and uncertainties
( SL + HL ) 2 The SI system of fundamental and derived units , SI System, fundamental and derived units and give examples of derived units, different units of quantities, units in the accepted SI format, scientific notation and in multiples of units with appropriate prefixes , Uncertainty and error in measurement, random and systematic errors, precision and accuracy, the effects of random errors may be reduced. Uncertainties in calculated results , uncertainties as absolute, fractional and percentage uncertainties. uncertainties in results. Uncertainties in graphs uncertainties as error bars in graphs. random uncertainty as an uncertainty range (±) and represent it graphically as an “error bar”, the uncertainties in the gradient and intercepts of a straight line graph.
Vectors and scalars
( SL + HL ) 2 vector and scalar , quantities, and give examples of each, the sum or difference of two vectors by a graphical method, Resolve vectors into perpendicular components along chosen axes.
Kinematics
( SL + HL ) 6 displacement, velocity, speed and acceleration, the difference between instantaneous and average values of speed, velocity and acceleration, the conditions under which the equations for uniformly accelerated motion may be applied, the acceleration of a body falling in a vacuum near , the Earth’s surface with the acceleration g of free fall, equations of uniformly accelerated motion, the effects of air resistance on falling objects, distance–time graphs, displacement–time graphs, velocity–time graphs and acceleration–time graphs. the gradients of displacement–time graphs and velocity–time graphs, and the areas Under velocity–time graphs an acceleration–time graphs. relative velocity in one and in two dimensions.
Forces and dynamics
( SL + HL ) 6 weight of a body using the expression W = mg, the forces acting on an object and draw free-body diagrams representing the forces acting, the resultant force in different situations. Newton’s first law of motion, examples of Newton’s first law, the condition for translational equilibrium. problems involving translational equilibrium. Newton’s second law of motion, problems involving Newton’s second law. linear momentum and impulse, the impulse due to a time-varying force by interpreting a force–time graph, the law of conservation of linear momentum, problems involving momentum and impulse. Newton’s third law of motion, examples of Newton’s third law.
Work, energy and power
( SL + HL ) 3 Work, the work done by a non-constant force by interpreting a force–displacement graph, problems involving the work done by a force. kinetic, Energy, change in gravitational potential energy, the principle of conservation of Energy, List different forms of energy and describe examples of the transformation of energy from one form to another. power, the concept of Efficiency, momentum, work, energy and power.
Uniform circular motion
( SL + HL ) 2 vector diagram to illustrate that the acceleration of a particle
moving with constant speed in a circle is directed towards the centre of the circle, the expression for centripetal acceleration, force producing circular motion in various situations, problems involving circular motion.
Projectile motion
(HL) 2 The independence of the vertical and the horizontal components of velocity for a projectile in a uniform field, the trajectory of projectile motion as parabolic in the absence of air resistance, Describe qualitatively the effect of air resistance on the trajectory of a projectile, problems on projectile motion.
Gravitational field, potential and energy
(HL) 2 Gravitational potential and gravitational potential energy, the formula relating gravitational field strength to gravitational potential gradient, the potential due to one or more point masses, sketch the pattern of equipotential surfaces due to one and two point masses, the relation between equipotential surfaces and gravitational field lines.
Electric field, potential and energy
(HL) 2 Electric potential and electric potential energy, the expression for electric potential due to a point charge, the formula relating electric field strength to electric potential gradient, the potential due to one or more point charges, the pattern of equipotential surfaces due to one and two point charges, the relation between equipotential surfaces and electric field lines, the concept of escape speed from a planet, an expression for the escape speed of an object from the surface of a planet, problems involving gravitational potential energy and gravitational potential., problems involving electric potential energy and electric potential.
Orbital motion
(HL) 2 Gravitation provides the centripetal force for circular orbital motion, Kepler’s third law, expressions for the kinetic
energy, potential energy and total energy of an orbiting satellite, the variation with orbital radius of the kinetic energy, gravitational potential energy and total energy of a satellite, the concept of “weightless-ness” in orbital motion, in free fall and in deep space, problems involving orbital motion.
Thermal concepts
( SL + HL ) 2 Temperature determines the direction of thermal energy transfer between two objects, relation between the Kelvin and Celsius scales of temperature, the internal energy of a substance is the total potential energy and random kinetic energy of the molecules of the substance. the macroscopic concepts of temperature, internal energy and thermal energy (heat). the mole and molar mass. the Avogadro constant.
Thermal properties of matter
( SL + HL ) 5 Specific heat capacity, phase changes and latent heat, Kinetic model of an ideal gas, Pressure, the assumptions of the kinetic model of an ideal gas, temperature is a measure of the average random kinetic energy of the molecules of an ideal gas, the macroscopic behaviour of an ideal gas in terms of a molecular model.
Thermodynamics
2 the equation of state for an ideal gas, the difference between an
ideal gas and a real gas, the concept of the absolute zero of temperature and the Kelvin scale of temperature, problems using the equation of state of an ideal gas.
Processes
3 The first law of thermodynamics, an expression for the work involved in a volume change of a gas at constant pressure, the first law of thermodynamics, the first law of thermodynamics as a statement of the principle of energy conservation, the isochoric (isovolumetric), isobaric, isothermal and adiabatic changes of state of an ideal gas, thermodynamic processes and cycles on P–V diagrams, P–V diagram the work done in a thermodynamic cycle, problems involving state changes of a gas.
Second law of thermodynamics and entropy
1 The second law of thermodynamics implies that thermal energy cannot spontaneously transfer from a region of low temperature to a region of high temperature; entropy is a system property that expresses the degree of disorder in the system, the second law of thermodynamics in terms of entropy changes, examples of natural processes in terms of entropy changes.
Kinematics of simple harmonic motion
( SL + HL ) 2 examples of oscillations, displacement, amplitude, frequency, period and phase difference, simple harmonic motion (SHM) and state the defining equation as a = −ω2x ., problems using the defining equation for SHM, Solve problems, both graphically and by calculation, for acceleration, velocity and displacement during SHM.
Energy changes during simple harmonic motion (SHM)
( SL + HL ) 1 the interchange between kinetic energy and potential energy during SHM, Solve problems, both graphically and by calculation, involving energy changes during SHM.
Forced oscillations and resonance
( SL + HL ) 3 Damping, examples of damped Oscillations, natural frequency of vibration and forced oscillations, graphically the variation with forced frequency of the amplitude of vibration of an object close to its natural frequency of vibration, resonance, examples of resonance where the effect is useful and where it should be avoided.
Wave characteristics
( SL + HL ) 2 Wave pulse and a continuous progressive (travelling) wave, progressive (travelling) waves transfer energy, transverse and of longitudinal waves, waves in two dimensions, including the concepts of wavefronts and of rays. Crest, trough, compression and rarefaction. Displacement, amplitude, frequency, period, wavelength, wave speed and intensity. displacement–time graphs and displacement –position graphs for transverse and for longitudinal waves. the relationship between wave speed, wavelength and frequency. Electro-magnetic waves travel with the same speed in free space, and recall the orders of magnitude of the wavelengths of the principal radiations in the electro-magnetic spectrum.
Wave properties
( SL + HL ) 2 the reflection and transmission of waves at a boundary between two media. Snell’s law. The diffraction of waves at apertures and obstacles diffraction, principle of superposition and explain what is meant by constructive interference and by destructive interference, the conditions for constructive and for destructive interference in terms of path difference and phase difference. principle of super-position to determine the resultant of two waves.
Standing (stationary) waves
2 The nature of standing (stationary) waves, the formation of One-dimensional standing waves, the modes of vibration of strings and air in open and in closed pipes, Compare standing waves and travelling waves , problems involving standing waves.
Doppler effect
2 what is meant by the Doppler effect., the Doppler effect by reference to wavefront diagrams for moving-detector and moving-source situations, the Doppler effect equations for sound.
Diffraction
1 Diffraction at a single slit, the variation with angle of diffraction of the relative intensity of light diffracted at a single slit, Derive the formula
θ = λ
b
for the position of the first minimum of the diffraction pattern produced at a single slit, problems involving single-slit diffraction.
Resolution
4 the variation with angle of
diffraction of the relative intensity of light emitted by two point sources that has been diffracted at a single slit, the Rayleigh criterion for images of two sources to be just resolved, the significance of resolution in the development of devices such as CDs and DVDs, the electron microscope and radio telescopes.
Polarization
3 what is meant by polarized light, polarization by reflection, Brewster’s law, the terms polarizer and analyzer, the intensity of a transmitted beam of polarized light using Malus’ law, the use of polarization in the determination of the concentration of certain solutions, qualitatively the action of liquid-crystal displays (LCDs).
Electric potential difference, current and resistance
( SL + HL ) 7 Electric potential difference, the change in potential energy when a charge moves between two points at different potentials, the electron-volt, problems involving electric potential difference.
Electric current and resistance, Apply the equation for resistance in the form
R = ρ L
A
where ρ is the resistivity of the material of the resistor. Ohm’s law, ohmic and non-ohmic behaviour. Expressions for electrical power dissipation in resistors, problems involving potential difference, current and resistance.
Electric circuits
( SL + HL ) 3 electromotive force (emf), the concept of internal resistance, Apply the equations for resistors in series and in parallel, Draw circuit diagrams, the use of ideal ammeters and ideal voltmeters, a potential divider, the use of
sensors in potential divider circuits, problems involving electric circuits,
Induced electromotive force
3 the inducing of an emf by relative motion between a conductor and a magnetic field, the formula for the emf induced in a straight conductor moving in a magnetic field, magnetic flux and magnetic flux linkage, the production of an induced emf by a time-changing magnetic flux, Faraday’s law and Lenz’s law, electromagnetic induction problems.
Alternating current
2 the emf induced in a coil rotating within a uniform magnetic field, the operation of a basic alternating current (ac) generator, the effect on the induced emf of changing the generator frequency, the relation between peak and rms values for sinusoidal currents and voltages, ac circuit problems for ohmic resistors, the operation of an ideal transformer.
Transmission of electrical power
1 the reasons for power losses in transmission lines and real transformers., the use of high-voltage stepup and step-down transformers in the transmission of electrical power, problems on the operation of real transformers and power transmission, Discuss some of the possible risks involved in living and working 0near high-voltage power lines.
Gravitational force and field
( SL + HL ) 2 Newton’s universal law of
Gravitation, gravitational field strength, the gravitational field due to one or more point masses, expression for gravitational field strength at the surface of a planet, assuming that all its mass is concentrated at its centre, problems involving gravitational forces and fields.
Magnetic force and field
( SL + HL ) 3 Moving charges give rise to magnetic fields, magnetic field patterns due to currents, the direction of the force on a current-carrying conductor in a magnetic field, the direction of the force on a charge moving in a magnetic field, the magnitude and direction of a magnetic field, problems involving magnetic forces, fields and currents.
The atom
( SL + HL ) 2 Atomic structure
model of the atom that features a small nucleus surrounded by electron, the evidence that supports a nuclear model of the atom, Outline one limitation of the simple model of the nuclear atom, Outline evidence for the existence of atomic energy levels, Nuclear structure, the terms nuclide, isotope and nucleon, Define nucleon number A, proton number Z and neutron number N,the interactions in a nucleus.
Radioactive decay
( SL + HL ) 3 Radioactivity :the phenomenon of natural radioactive decay, the properties of alpha (α) and beta (β) particles and gamma (γ) radiation.8the ionizing properties of alpha (α) and beta (β) particles and gamma (γ) radiation, the biological effects of ionizing radiation, Half-life ,radioactive decay is a random and spontaneous process and that the rate of decay decreases exponentially with time, the term radioactive half-life, the half-life of a nuclide from a decay curve, radioactive decay problems involving integral numbers of half lives.
Nuclear reactions, fission and fusion
( SL + HL ) 4 Nuclear reactions, an example of an artificial (induced) transmutation, Construct and complete nuclear equations, Define the term unified atomic mass unit, the Einstein mass–energy equivalence relationship, the concepts of mass defect, binding energy and binding energy per nucleon, graph showing the variation with nucleon number of the binding energy per nucleon, problems involving mass defect and binding energy, Fission and fusion, the processes of nuclear fission and nuclear fusion, State that nuclear fusion is the main
source of the Sun’s energy, Solve problems involving fission and fusion reactions.
Quantum physics
10 The quantum nature of radiation, the photoelectric effect, the concept of the photon, and use it to explain the photoelectric effect, an experiment to test the Einstein model, problems involving the photoelectric effect, The wave nature of matter, the de Broglie hypothesis and the concept of matter waves, an experiment to verify the de Broglie hypothesis, problems involving matter waves, Atomic spectra and atomic energy states, a laboratory procedure for producing and observing atomic spectra, the Schrödinger model of the hydrogen atom, the Heisenberg uncertainty principle with regard to position–momentum and time–energy.
Nuclear physics
5 the radii of nuclei may be estimated from charged particle scattering experiments, the masses of nuclei may be determined using a Bainbridge mass spectrometer, Describe one piece of evidence for the existence of nuclear energy levels, Radioactive decay, Describe β+ decay, including the existence of the neutrino, the radioactive decay law as an exponential function and define the decay constant, the relationship between decay constant and half-life.
Energy degradation and power generation
( SL + HL ) 2 Thermal energy may be completely converted to work in a single process, but that continuous conversion of this energy into work requires a cyclical process and the transfer of some energy from the system, what is meant by degraded energy, Construct and analyse energy flow diagrams (Sankey diagrams) and identify where the energy is degraded¸ Outline the principal mechanisms involved in the production of electrical power.
World energy sources
( SL + HL ) 2 Identify different world energy Sources, Outline and distinguish between renewable and non-renewable energy sources, the energy density of a fuel, the relative proportions of world use of the different energy sources that are available, the relative advantages and disadvantages of various energy sources.
Fossil fuel power production
( SL + HL ) 1 the historical and geographical reasons for the widespread use of fossil fuels, Discuss the energy density of fossil fuels with respect to the demands of power stations, the relative advantages and disadvantages associated with the transportation and storage of fossil fuels, the overall efficiency of power stations fuelled by different fossil fuels, the environmental problems associated with the recovery of fossil fuels and their use in power stations.
Non-fossil fuel power production
( SL + HL ) 7 Nuclear power , how neutrons produced in a fission reaction may be used to initiate further fission reactions (chain reaction), Distinguish between controlled nuclear fission (power production) and uncontrolled nuclear fission (nuclear weapons), what is meant by fuel Enrichment, the main energy transformations that take place in a nuclear power station, the role of the moderator and the control rods in the production of
controlled fission in a thermal fission reactor, the role of the heat exchanger in a fission reactor, how neutron capture by a nucleus of uranium-238 (238U) results in the production of a nucleus of plutonium-239 (239Pu), the importance of plutonium-239 (239Pu) as a nuclear fuel, Discuss safety issues and risks associated with the production of nuclear power, the problems associated with producing nuclear power using
nuclear fusion, problems on the production of nuclear power, Solar power, Distinguish between a photovoltaic cell and a solar heating panel, Solve problems involving specific applications of photovoltaic cells and solar heating panels, Hydroelectric power, Distinguish between different hydroelectric schemes , the main energy transformations that take place in hydroelectric schemes, Solve problems involving hydroelectric schemes, Wind power, Outline the basic features of a wind
generator, the power that may be delivered by a wind generator, assuming that the wind kinetic energy is completely converted into mechanical kinetic energy, and explain why this is impossible, Wave power.
Greenhouse effect
( SL + HL ) 3 Solar radiation, the intensity of the Sun’s radiation incident on a planet, State factors that determine a planet’s albedo, The greenhouse effect, Identify the main greenhouse gases and their sources, the molecular mechanism by which greenhouse gases absorb infrared radiation, surface heat capacity Cs, problems on the greenhouse effect and the heating of planets using a simple energy balance climate model.
Global warming
( SL + HL ) 3 Global warming, some possible models of global warming, what is meant by the enhanced Green-house effect, the evidence that links global warming to increased levels of greenhouse gases, Outline some of the mechanisms that may increase the rate of global
warming, coefficient of volume expansion, possible effect of the enhanced greenhouse effect is a rise in mean sea-level, Identify climate change as an outcome of the enhanced green house effect, international efforts to reduce the enhanced greenhouse effect.
Analogue and digital signals
4 problems involving the conversion between binary numbers and decimal numbers, Describe different means of storage of information in both analogue and digital forms, how interference of light is used to recover information stored on a CD, an appropriate depth for a pit from the wavelength of the laser light, problems on CDs and DVDs related to data storage capacity, the advantage of the storage of information in digital rather than analogue form, the implications for society of ever-increasing capability of data storage.
Data capture; digital imaging using charge-coupled devices
(CCDs)
4 Capacitance, the structure of a charge- coupled device (CCD), how incident light causes charge to build up within a pixel, how the image on a CCD is Digitized, quantum efficiency of a pixel, magnification, two points on an object may be just resolved on a CCD if the images of the points are at least two pixels apart, the effects of quantum efficiency, magnification and resolution on the quality of the processed image, a range of practical uses
of a CCD, and list some advantages compared with the use of film, Outline how the image stored in a CCD is retrieved, problems involving the use of CCDs.
Radio communication
5 The modulation of a wave, carrier wave and a signal wave, the nature of amplitude modulation (AM) and frequency
modulation (FM), the modulation of the carrier wave in order to determine the frequency and
amplitude of the information signal, analyse graphs of the
power spectrum of a carrier wave that is amplitude-modulated by a single- frequency signal, sideband frequencies and bandwidth, sideband frequencies and bandwidth, the relative advantages and disadvantages of AM and FM for radio transmission and reception, block diagram, an AM radio receiver,.
Digital signals
4 the conversion between binary numbers and decimal numbers, analogue and digital signals, the advantages of the digital transmission, as compared to the analogue transmission, of information , analogue and
digital signals, the advantages of the digital transmission, as compared to the analogue transmission, of information, using block diagrams, the principles of the transmission and reception of digital signals, the significance of the number of bits and the bit-rate on the reproduction of a transmitted signal, time-division multiplexing, analogue- to-digital conversion, the consequences of digital
communication and multiplexing on worldwide communications, the moral, ethical, economic
and environmental issues arising from access to the Internet.
Optic fibre transmission
3 critical angle and total internal reflection, refractive index and critical angle, the concept of total internal reflection to the transmission of light along an optic fibre, the effects of material
dispersion and modal dispersion, attenuation and solve problems involving attenuation measured in decibels, the variation with wavelength of the attenuation of
radiation in the core of a monomode fibre, noise in an
optic fibre, the role of amplifiers and reshapers in optic fibre transmission, optic fibres.
Channels of communication
3 different channels of communication, including wire pairs, coaxial cables, optic fibres, radio waves and satellite communication, the uses and the relative advantages and disadvantages of wire pairs, coaxial cables, optic fibres and radio waves, geostationary satellite, the order of magnitude of the frequencies used for communication with geo-stationary satellites, and xplain why the up-link frequency nd the down-link frequency are ifferent, the relative advantages and disadvantages of the use of
geo-stationary and of polar-orbiting satellites for communication, the moral, ethical, economic and environmental issues arising from satellite communication.
Electronics
5 the properties of an ideal operational amplifier (op-amp), circuit diagrams for both inverting and non-inverting amplifiers (with a single input) incorporating operational amplifiers, an expression for the gain of an inverting amplifier and for a noninverting amplifier, the use of an operational amplifier circuit as a comparator, the use of a Schmitt trigger for the reshaping of digital pulses, problems involving circuits
incorporating operational amplifiers.
The mobile phone system
2 number of cells (each with its own base station) to which is allocated a range of frequencies, the role of the cellular exchange and the public switched telephone network (PSTN) in communications using mobile phones, the use of mobile phones in multimedia communication, the moral, ethical, economic, environmental and international issues arising from the use of mobile phones.
The nature of EM waves and light sources
4 the nature of electromagnetic (EM) waves, the different regions of the electromagnetic spectrum, the dispersion of EM waves, the dispersion of EM waves in terms of the dependence of refractive index on wavelength, transmission, absorption and scattering of radiation, the transmission, absorption and scattering of EM
radiation, Lasers, the terms monochromatic and coherent, laser light as a source of coherent light, the mechanism for the production of laser light, an application of the use of a laser.
Optical instruments
6 the terms principal axis, focal point, focal length and linear
magnification as applied to a converging (convex) lens, the power of a convex lens and the dioptre, linear magnification, ray diagrams to locate the image formed by a convex lens, real image and a virtual image, the convention “real is positive, virtual is negative” to the thin lens formula, single convex lens using the thin lens formula, The simple magnifying glass, the terms far point and near point for the unaided eye, angular magnification, an expression for the angular magnification of a simple magnifying glass for an image formed at the near point and at infinity, The compound microscope and astronomical telescope, ray diagram for a
compound microscope with final
image formed close to the near point of the eye (normal adjustment), a ray diagram for an astronomical telescope with the final image at infinity (normal adjustment), the equation relating angular magnification to the focal lengths of the lenses in an astronomical telescope in normal adjustment, the compound microscope and the
astronomical telescope, Aberrations, the meaning of spherical aberration and of chromatic aberration as produced by a single lens, spherical aberration in a lens may be reduced, chromatic aberration in a lens may be reduced.
Two-source interference of waves
3 the conditions necessary to observe interference between two sources, the principle of superposition, the interference
pattern produced by waves from two coherent point sources, double-slit experiment for light and draw the intensity distribution of the observed fringe pattern, two-source interference.
Diffraction grating
2 Multiple-slit diffraction, the effect on the double-slit intensity distribution of increasing the number of slits, the diffraction grating formula for normal incidence, the use of a diffraction grating to measure wavelengths, problems involving a diffraction grating.
X-rays
4 the experimental arrangement for the production of X-rays, annotate a typical X-ray Spectrum, the origins of the features of a characteristic X-ray spectrum, accelerating potential difference and minimum wavelength, X-ray diffraction, X-ray diffraction arises from the scattering of X-rays in a crystal, the Bragg scattering equation, cubic crystals may be used to measure the wavelength of X-rays, X-rays may be used to determine the structure of crystals, problems involving the Bragg equation.
Thin-film interference
3 Wedge films, the production of interference fringes by a thin air wedge, how wedge fringes can be used to measure very small separations, how thin-film interference is used to test optical flats, Solve problems involving wedge films, Parallel films, the condition for light to undergo either a phase change of π, or no phase change, on reflection from an interface, how a source of light gives rise to an interference pattern when the light is reflected at both surfaces
of a parallel film, the conditions for constructive and destructive interference, the formation of coloured fringes when white light is reflected from thin films, such as oil and soap films, the difference between fringes formed by a parallel film and a
wedge film, applications of parallel thin films, problems involving parallel films.
The realm of physics
( SL + HL ) 1 To understand range of magnitudes of quantities in our , universe order of magnitude, ranges of magnitude of distances, masses and times that occur in the universe, from smallest to greatest., differences of orders of magnitude.
Measurement and uncertainties
( SL + HL ) 2 The SI system of fundamental and derived units , SI System, fundamental and derived units and give examples of derived units, different units of quantities, units in the accepted SI format, scientific notation and in multiples of units with appropriate prefixes , Uncertainty and error in measurement, random and systematic errors, precision and accuracy, the effects of random errors may be reduced. Uncertainties in calculated results , uncertainties as absolute, fractional and percentage uncertainties. uncertainties in results. Uncertainties in graphs uncertainties as error bars in graphs. random uncertainty as an uncertainty range (±) and represent it graphically as an “error bar”, the uncertainties in the gradient and intercepts of a straight line graph.
Vectors and scalars
( SL + HL ) 2 vector and scalar , quantities, and give examples of each, the sum or difference of two vectors by a graphical method, Resolve vectors into perpendicular components along chosen axes.
Kinematics
( SL + HL ) 6 displacement, velocity, speed and acceleration, the difference between instantaneous and average values of speed, velocity and acceleration, the conditions under which the equations for uniformly accelerated motion may be applied, the acceleration of a body falling in a vacuum near , the Earth’s surface with the acceleration g of free fall, equations of uniformly accelerated motion, the effects of air resistance on falling objects, distance–time graphs, displacement–time graphs, velocity–time graphs and acceleration–time graphs. the gradients of displacement–time graphs and velocity–time graphs, and the areas Under velocity–time graphs an acceleration–time graphs. relative velocity in one and in two dimensions.
Forces and dynamics
( SL + HL ) 6 weight of a body using the expression W = mg, the forces acting on an object and draw free-body diagrams representing the forces acting, the resultant force in different situations. Newton’s first law of motion, examples of Newton’s first law, the condition for translational equilibrium. problems involving translational equilibrium. Newton’s second law of motion, problems involving Newton’s second law. linear momentum and impulse, the impulse due to a time-varying force by interpreting a force–time graph, the law of conservation of linear momentum, problems involving momentum and impulse. Newton’s third law of motion, examples of Newton’s third law.
Work, energy and power
( SL + HL ) 3 Work, the work done by a non-constant force by interpreting a force–displacement graph, problems involving the work done by a force. kinetic, Energy, change in gravitational potential energy, the principle of conservation of Energy, List different forms of energy and describe examples of the transformation of energy from one form to another. power, the concept of Efficiency, momentum, work, energy and power.
Uniform circular motion
( SL + HL ) 2 vector diagram to illustrate that the acceleration of a particle
moving with constant speed in a circle is directed towards the centre of the circle, the expression for centripetal acceleration, force producing circular motion in various situations, problems involving circular motion.
Projectile motion
(HL) 2 The independence of the vertical and the horizontal components of velocity for a projectile in a uniform field, the trajectory of projectile motion as parabolic in the absence of air resistance, Describe qualitatively the effect of air resistance on the trajectory of a projectile, problems on projectile motion.
Gravitational field, potential and energy
(HL) 2 Gravitational potential and gravitational potential energy, the formula relating gravitational field strength to gravitational potential gradient, the potential due to one or more point masses, sketch the pattern of equipotential surfaces due to one and two point masses, the relation between equipotential surfaces and gravitational field lines.
Electric field, potential and energy
(HL) 2 Electric potential and electric potential energy, the expression for electric potential due to a point charge, the formula relating electric field strength to electric potential gradient, the potential due to one or more point charges, the pattern of equipotential surfaces due to one and two point charges, the relation between equipotential surfaces and electric field lines, the concept of escape speed from a planet, an expression for the escape speed of an object from the surface of a planet, problems involving gravitational potential energy and gravitational potential., problems involving electric potential energy and electric potential.
Orbital motion
(HL) 2 Gravitation provides the centripetal force for circular orbital motion, Kepler’s third law, expressions for the kinetic
energy, potential energy and total energy of an orbiting satellite, the variation with orbital radius of the kinetic energy, gravitational potential energy and total energy of a satellite, the concept of “weightless-ness” in orbital motion, in free fall and in deep space, problems involving orbital motion.
Thermal concepts
( SL + HL ) 2 Temperature determines the direction of thermal energy transfer between two objects, relation between the Kelvin and Celsius scales of temperature, the internal energy of a substance is the total potential energy and random kinetic energy of the molecules of the substance. the macroscopic concepts of temperature, internal energy and thermal energy (heat). the mole and molar mass. the Avogadro constant.
Thermal properties of matter
( SL + HL ) 5 Specific heat capacity, phase changes and latent heat, Kinetic model of an ideal gas, Pressure, the assumptions of the kinetic model of an ideal gas, temperature is a measure of the average random kinetic energy of the molecules of an ideal gas, the macroscopic behaviour of an ideal gas in terms of a molecular model.
Thermodynamics
2 the equation of state for an ideal gas, the difference between an
ideal gas and a real gas, the concept of the absolute zero of temperature and the Kelvin scale of temperature, problems using the equation of state of an ideal gas.
Processes
3 The first law of thermodynamics, an expression for the work involved in a volume change of a gas at constant pressure, the first law of thermodynamics, the first law of thermodynamics as a statement of the principle of energy conservation, the isochoric (isovolumetric), isobaric, isothermal and adiabatic changes of state of an ideal gas, thermodynamic processes and cycles on P–V diagrams, P–V diagram the work done in a thermodynamic cycle, problems involving state changes of a gas.
Second law of thermodynamics and entropy
1 The second law of thermodynamics implies that thermal energy cannot spontaneously transfer from a region of low temperature to a region of high temperature; entropy is a system property that expresses the degree of disorder in the system, the second law of thermodynamics in terms of entropy changes, examples of natural processes in terms of entropy changes.
Kinematics of simple harmonic motion
( SL + HL ) 2 examples of oscillations, displacement, amplitude, frequency, period and phase difference, simple harmonic motion (SHM) and state the defining equation as a = −ω2x ., problems using the defining equation for SHM, Solve problems, both graphically and by calculation, for acceleration, velocity and displacement during SHM.
Energy changes during simple harmonic motion (SHM)
( SL + HL ) 1 the interchange between kinetic energy and potential energy during SHM, Solve problems, both graphically and by calculation, involving energy changes during SHM.
Forced oscillations and resonance
( SL + HL ) 3 Damping, examples of damped Oscillations, natural frequency of vibration and forced oscillations, graphically the variation with forced frequency of the amplitude of vibration of an object close to its natural frequency of vibration, resonance, examples of resonance where the effect is useful and where it should be avoided.
Wave characteristics
( SL + HL ) 2 Wave pulse and a continuous progressive (travelling) wave, progressive (travelling) waves transfer energy, transverse and of longitudinal waves, waves in two dimensions, including the concepts of wavefronts and of rays. Crest, trough, compression and rarefaction. Displacement, amplitude, frequency, period, wavelength, wave speed and intensity. displacement–time graphs and displacement –position graphs for transverse and for longitudinal waves. the relationship between wave speed, wavelength and frequency. Electro-magnetic waves travel with the same speed in free space, and recall the orders of magnitude of the wavelengths of the principal radiations in the electro-magnetic spectrum.
Wave properties
( SL + HL ) 2 the reflection and transmission of waves at a boundary between two media. Snell’s law. The diffraction of waves at apertures and obstacles diffraction, principle of superposition and explain what is meant by constructive interference and by destructive interference, the conditions for constructive and for destructive interference in terms of path difference and phase difference. principle of super-position to determine the resultant of two waves.
Standing (stationary) waves
2 The nature of standing (stationary) waves, the formation of One-dimensional standing waves, the modes of vibration of strings and air in open and in closed pipes, Compare standing waves and travelling waves , problems involving standing waves.
Doppler effect
2 what is meant by the Doppler effect., the Doppler effect by reference to wavefront diagrams for moving-detector and moving-source situations, the Doppler effect equations for sound.
Diffraction
1 Diffraction at a single slit, the variation with angle of diffraction of the relative intensity of light diffracted at a single slit, Derive the formula
θ = λ
b
for the position of the first minimum of the diffraction pattern produced at a single slit, problems involving single-slit diffraction.
Resolution
4 the variation with angle of
diffraction of the relative intensity of light emitted by two point sources that has been diffracted at a single slit, the Rayleigh criterion for images of two sources to be just resolved, the significance of resolution in the development of devices such as CDs and DVDs, the electron microscope and radio telescopes.
Polarization
3 what is meant by polarized light, polarization by reflection, Brewster’s law, the terms polarizer and analyzer, the intensity of a transmitted beam of polarized light using Malus’ law, the use of polarization in the determination of the concentration of certain solutions, qualitatively the action of liquid-crystal displays (LCDs).
Electric potential difference, current and resistance
( SL + HL ) 7 Electric potential difference, the change in potential energy when a charge moves between two points at different potentials, the electron-volt, problems involving electric potential difference.
Electric current and resistance, Apply the equation for resistance in the form
R = ρ L
A
where ρ is the resistivity of the material of the resistor. Ohm’s law, ohmic and non-ohmic behaviour. Expressions for electrical power dissipation in resistors, problems involving potential difference, current and resistance.
Electric circuits
( SL + HL ) 3 electromotive force (emf), the concept of internal resistance, Apply the equations for resistors in series and in parallel, Draw circuit diagrams, the use of ideal ammeters and ideal voltmeters, a potential divider, the use of
sensors in potential divider circuits, problems involving electric circuits,
Induced electromotive force
3 the inducing of an emf by relative motion between a conductor and a magnetic field, the formula for the emf induced in a straight conductor moving in a magnetic field, magnetic flux and magnetic flux linkage, the production of an induced emf by a time-changing magnetic flux, Faraday’s law and Lenz’s law, electromagnetic induction problems.
Alternating current
2 the emf induced in a coil rotating within a uniform magnetic field, the operation of a basic alternating current (ac) generator, the effect on the induced emf of changing the generator frequency, the relation between peak and rms values for sinusoidal currents and voltages, ac circuit problems for ohmic resistors, the operation of an ideal transformer.
Transmission of electrical power
1 the reasons for power losses in transmission lines and real transformers., the use of high-voltage stepup and step-down transformers in the transmission of electrical power, problems on the operation of real transformers and power transmission, Discuss some of the possible risks involved in living and working 0near high-voltage power lines.
Gravitational force and field
( SL + HL ) 2 Newton’s universal law of
Gravitation, gravitational field strength, the gravitational field due to one or more point masses, expression for gravitational field strength at the surface of a planet, assuming that all its mass is concentrated at its centre, problems involving gravitational forces and fields.
Magnetic force and field
( SL + HL ) 3 Moving charges give rise to magnetic fields, magnetic field patterns due to currents, the direction of the force on a current-carrying conductor in a magnetic field, the direction of the force on a charge moving in a magnetic field, the magnitude and direction of a magnetic field, problems involving magnetic forces, fields and currents.
The atom
( SL + HL ) 2 Atomic structure
model of the atom that features a small nucleus surrounded by electron, the evidence that supports a nuclear model of the atom, Outline one limitation of the simple model of the nuclear atom, Outline evidence for the existence of atomic energy levels, Nuclear structure, the terms nuclide, isotope and nucleon, Define nucleon number A, proton number Z and neutron number N,the interactions in a nucleus.
Radioactive decay
( SL + HL ) 3 Radioactivity :the phenomenon of natural radioactive decay, the properties of alpha (α) and beta (β) particles and gamma (γ) radiation.8the ionizing properties of alpha (α) and beta (β) particles and gamma (γ) radiation, the biological effects of ionizing radiation, Half-life ,radioactive decay is a random and spontaneous process and that the rate of decay decreases exponentially with time, the term radioactive half-life, the half-life of a nuclide from a decay curve, radioactive decay problems involving integral numbers of half lives.
Nuclear reactions, fission and fusion
( SL + HL ) 4 Nuclear reactions, an example of an artificial (induced) transmutation, Construct and complete nuclear equations, Define the term unified atomic mass unit, the Einstein mass–energy equivalence relationship, the concepts of mass defect, binding energy and binding energy per nucleon, graph showing the variation with nucleon number of the binding energy per nucleon, problems involving mass defect and binding energy, Fission and fusion, the processes of nuclear fission and nuclear fusion, State that nuclear fusion is the main
source of the Sun’s energy, Solve problems involving fission and fusion reactions.
Quantum physics
10 The quantum nature of radiation, the photoelectric effect, the concept of the photon, and use it to explain the photoelectric effect, an experiment to test the Einstein model, problems involving the photoelectric effect, The wave nature of matter, the de Broglie hypothesis and the concept of matter waves, an experiment to verify the de Broglie hypothesis, problems involving matter waves, Atomic spectra and atomic energy states, a laboratory procedure for producing and observing atomic spectra, the Schrödinger model of the hydrogen atom, the Heisenberg uncertainty principle with regard to position–momentum and time–energy.
Nuclear physics
5 the radii of nuclei may be estimated from charged particle scattering experiments, the masses of nuclei may be determined using a Bainbridge mass spectrometer, Describe one piece of evidence for the existence of nuclear energy levels, Radioactive decay, Describe β+ decay, including the existence of the neutrino, the radioactive decay law as an exponential function and define the decay constant, the relationship between decay constant and half-life.
Energy degradation and power generation
( SL + HL ) 2 Thermal energy may be completely converted to work in a single process, but that continuous conversion of this energy into work requires a cyclical process and the transfer of some energy from the system, what is meant by degraded energy, Construct and analyse energy flow diagrams (Sankey diagrams) and identify where the energy is degraded¸ Outline the principal mechanisms involved in the production of electrical power.
World energy sources
( SL + HL ) 2 Identify different world energy Sources, Outline and distinguish between renewable and non-renewable energy sources, the energy density of a fuel, the relative proportions of world use of the different energy sources that are available, the relative advantages and disadvantages of various energy sources.
Fossil fuel power production
( SL + HL ) 1 the historical and geographical reasons for the widespread use of fossil fuels, Discuss the energy density of fossil fuels with respect to the demands of power stations, the relative advantages and disadvantages associated with the transportation and storage of fossil fuels, the overall efficiency of power stations fuelled by different fossil fuels, the environmental problems associated with the recovery of fossil fuels and their use in power stations.
Non-fossil fuel power production
( SL + HL ) 7 Nuclear power , how neutrons produced in a fission reaction may be used to initiate further fission reactions (chain reaction), Distinguish between controlled nuclear fission (power production) and uncontrolled nuclear fission (nuclear weapons), what is meant by fuel Enrichment, the main energy transformations that take place in a nuclear power station, the role of the moderator and the control rods in the production of
controlled fission in a thermal fission reactor, the role of the heat exchanger in a fission reactor, how neutron capture by a nucleus of uranium-238 (238U) results in the production of a nucleus of plutonium-239 (239Pu), the importance of plutonium-239 (239Pu) as a nuclear fuel, Discuss safety issues and risks associated with the production of nuclear power, the problems associated with producing nuclear power using
nuclear fusion, problems on the production of nuclear power, Solar power, Distinguish between a photovoltaic cell and a solar heating panel, Solve problems involving specific applications of photovoltaic cells and solar heating panels, Hydroelectric power, Distinguish between different hydroelectric schemes , the main energy transformations that take place in hydroelectric schemes, Solve problems involving hydroelectric schemes, Wind power, Outline the basic features of a wind
generator, the power that may be delivered by a wind generator, assuming that the wind kinetic energy is completely converted into mechanical kinetic energy, and explain why this is impossible, Wave power.
Greenhouse effect
( SL + HL ) 3 Solar radiation, the intensity of the Sun’s radiation incident on a planet, State factors that determine a planet’s albedo, The greenhouse effect, Identify the main greenhouse gases and their sources, the molecular mechanism by which greenhouse gases absorb infrared radiation, surface heat capacity Cs, problems on the greenhouse effect and the heating of planets using a simple energy balance climate model.
Global warming
( SL + HL ) 3 Global warming, some possible models of global warming, what is meant by the enhanced Green-house effect, the evidence that links global warming to increased levels of greenhouse gases, Outline some of the mechanisms that may increase the rate of global
warming, coefficient of volume expansion, possible effect of the enhanced greenhouse effect is a rise in mean sea-level, Identify climate change as an outcome of the enhanced green house effect, international efforts to reduce the enhanced greenhouse effect.
Analogue and digital signals
4 problems involving the conversion between binary numbers and decimal numbers, Describe different means of storage of information in both analogue and digital forms, how interference of light is used to recover information stored on a CD, an appropriate depth for a pit from the wavelength of the laser light, problems on CDs and DVDs related to data storage capacity, the advantage of the storage of information in digital rather than analogue form, the implications for society of ever-increasing capability of data storage.
Data capture; digital imaging using charge-coupled devices
(CCDs)
4 Capacitance, the structure of a charge- coupled device (CCD), how incident light causes charge to build up within a pixel, how the image on a CCD is Digitized, quantum efficiency of a pixel, magnification, two points on an object may be just resolved on a CCD if the images of the points are at least two pixels apart, the effects of quantum efficiency, magnification and resolution on the quality of the processed image, a range of practical uses
of a CCD, and list some advantages compared with the use of film, Outline how the image stored in a CCD is retrieved, problems involving the use of CCDs.
Radio communication
5 The modulation of a wave, carrier wave and a signal wave, the nature of amplitude modulation (AM) and frequency
modulation (FM), the modulation of the carrier wave in order to determine the frequency and
amplitude of the information signal, analyse graphs of the
power spectrum of a carrier wave that is amplitude-modulated by a single- frequency signal, sideband frequencies and bandwidth, sideband frequencies and bandwidth, the relative advantages and disadvantages of AM and FM for radio transmission and reception, block diagram, an AM radio receiver,.
Digital signals
4 the conversion between binary numbers and decimal numbers, analogue and digital signals, the advantages of the digital transmission, as compared to the analogue transmission, of information , analogue and
digital signals, the advantages of the digital transmission, as compared to the analogue transmission, of information, using block diagrams, the principles of the transmission and reception of digital signals, the significance of the number of bits and the bit-rate on the reproduction of a transmitted signal, time-division multiplexing, analogue- to-digital conversion, the consequences of digital
communication and multiplexing on worldwide communications, the moral, ethical, economic
and environmental issues arising from access to the Internet.
Optic fibre transmission
3 critical angle and total internal reflection, refractive index and critical angle, the concept of total internal reflection to the transmission of light along an optic fibre, the effects of material
dispersion and modal dispersion, attenuation and solve problems involving attenuation measured in decibels, the variation with wavelength of the attenuation of
radiation in the core of a monomode fibre, noise in an
optic fibre, the role of amplifiers and reshapers in optic fibre transmission, optic fibres.
Channels of communication
3 different channels of communication, including wire pairs, coaxial cables, optic fibres, radio waves and satellite communication, the uses and the relative advantages and disadvantages of wire pairs, coaxial cables, optic fibres and radio waves, geostationary satellite, the order of magnitude of the frequencies used for communication with geo-stationary satellites, and xplain why the up-link frequency nd the down-link frequency are ifferent, the relative advantages and disadvantages of the use of
geo-stationary and of polar-orbiting satellites for communication, the moral, ethical, economic and environmental issues arising from satellite communication.
Electronics
5 the properties of an ideal operational amplifier (op-amp), circuit diagrams for both inverting and non-inverting amplifiers (with a single input) incorporating operational amplifiers, an expression for the gain of an inverting amplifier and for a noninverting amplifier, the use of an operational amplifier circuit as a comparator, the use of a Schmitt trigger for the reshaping of digital pulses, problems involving circuits
incorporating operational amplifiers.
The mobile phone system
2 number of cells (each with its own base station) to which is allocated a range of frequencies, the role of the cellular exchange and the public switched telephone network (PSTN) in communications using mobile phones, the use of mobile phones in multimedia communication, the moral, ethical, economic, environmental and international issues arising from the use of mobile phones.
The nature of EM waves and light sources
4 the nature of electromagnetic (EM) waves, the different regions of the electromagnetic spectrum, the dispersion of EM waves, the dispersion of EM waves in terms of the dependence of refractive index on wavelength, transmission, absorption and scattering of radiation, the transmission, absorption and scattering of EM
radiation, Lasers, the terms monochromatic and coherent, laser light as a source of coherent light, the mechanism for the production of laser light, an application of the use of a laser.
Optical instruments
6 the terms principal axis, focal point, focal length and linear
magnification as applied to a converging (convex) lens, the power of a convex lens and the dioptre, linear magnification, ray diagrams to locate the image formed by a convex lens, real image and a virtual image, the convention “real is positive, virtual is negative” to the thin lens formula, single convex lens using the thin lens formula, The simple magnifying glass, the terms far point and near point for the unaided eye, angular magnification, an expression for the angular magnification of a simple magnifying glass for an image formed at the near point and at infinity, The compound microscope and astronomical telescope, ray diagram for a
compound microscope with final
image formed close to the near point of the eye (normal adjustment), a ray diagram for an astronomical telescope with the final image at infinity (normal adjustment), the equation relating angular magnification to the focal lengths of the lenses in an astronomical telescope in normal adjustment, the compound microscope and the
astronomical telescope, Aberrations, the meaning of spherical aberration and of chromatic aberration as produced by a single lens, spherical aberration in a lens may be reduced, chromatic aberration in a lens may be reduced.
Two-source interference of waves
3 the conditions necessary to observe interference between two sources, the principle of superposition, the interference
pattern produced by waves from two coherent point sources, double-slit experiment for light and draw the intensity distribution of the observed fringe pattern, two-source interference.
Diffraction grating
2 Multiple-slit diffraction, the effect on the double-slit intensity distribution of increasing the number of slits, the diffraction grating formula for normal incidence, the use of a diffraction grating to measure wavelengths, problems involving a diffraction grating.
X-rays
4 the experimental arrangement for the production of X-rays, annotate a typical X-ray Spectrum, the origins of the features of a characteristic X-ray spectrum, accelerating potential difference and minimum wavelength, X-ray diffraction, X-ray diffraction arises from the scattering of X-rays in a crystal, the Bragg scattering equation, cubic crystals may be used to measure the wavelength of X-rays, X-rays may be used to determine the structure of crystals, problems involving the Bragg equation.
Thin-film interference
3 Wedge films, the production of interference fringes by a thin air wedge, how wedge fringes can be used to measure very small separations, how thin-film interference is used to test optical flats, Solve problems involving wedge films, Parallel films, the condition for light to undergo either a phase change of π, or no phase change, on reflection from an interface, how a source of light gives rise to an interference pattern when the light is reflected at both surfaces
of a parallel film, the conditions for constructive and destructive interference, the formation of coloured fringes when white light is reflected from thin films, such as oil and soap films, the difference between fringes formed by a parallel film and a
wedge film, applications of parallel thin films, problems involving parallel films.
What is Radioactivity?
Unit 1.17 Radioactive Emissions
What is Radioactivity?
The nuclei of certain atoms are unstable. This may be because they have too many neutrons or too few neutrons or are just too big or have been left with too much energy after having changed to a more stable nucleus (decayed).
The atom
• Most matter is made up of atoms.
• An atom consists of two main parts.
The Nucleus
The orbiting electrons
The Nucleus
• The nucleus contains two sorts of particles - Protons and Neutrons.
• The nucleus contains all of the positive charge.
• The nucleus contains almost all of the mass of the atom.
• The size of the nucleus is very very small compared to the size of the atom.
The Orbiting Electrons
• The electrons are negatively charged.
• Because the whole atom has no overall charge,
the number of electrons = the number of protons.
• Electrons are very, very, very small and so an atom is mostly empty space.
The Particles in an Atom
Particle Mass Charge
Proton 1 a.m.u. +1 e
Neutron 1 a.m.u. 0
Electron 1/1840 a.m.u. -1 e
where 1 a.m.u. is one atomic mass unit.
and e is the size of the charge on an electron
Atomic Symbols
We can describe an atom by recording
the number of protons - the Atomic Number (the Proton Number Z)the number of nucleons - the Mass Number (the Nucleon Number A) the chemical symbol for the element.
Isotopes
• All of the atoms of an element have the same number of Protons.
• The atoms can have different numbers of neutrons.
• Versions of an element with different numbers of neutrons are called Isotopes.
• The Isotopes of an element have the same Atomic Number but different Mass Numbers.
• All elements have different Isotopes.
• Some Isotopes may be radioactive.
Models of the Atoms
Models of the Atoms
Dalton's Model
• Dalton's model of atoms was tiny spheres.
• These were thought to be the tiniest bits of matter that could exist.
• They could not be split into smaller bits.
The Electron and the Plum Pudding Model
• J.J.Thompson discovered the electron and showed that it was negatively charged, was very small and came from inside atoms.
• The new model was a positively charged sphere with electrons scattered about inside (the plums in the pudding).
• The negative charge on the electrons balanced the positive charge on the pudding.
Rutherford's Alpha Particle Scattering Experiment and the Nuclear Atom
Main Results
i. Most alpha particles go straight through the thin gold foil
ii. Some alpha particles are scattered through a small angle.
iii. A very small number are deflected through very large angles i.e. they bounce back
Alpha Radiation (a)
Ionising Ability
• Alpha radiation causes a great deal of ionization.
Absorption - Range
• Each time an alpha particle ionises an atom it uses some of its energy.
Because it ionises a lot of atoms per millimetre along its path, its range is short.
5 - 6cm of air or a thin sheet of paper will stop alpha radiation.
Electric Charge
• An alpha particle is positively charged.
It carries twice the charge of a proton, +2e.
( e is the size of the charge on an electron,
e = electronic charge = 1.6 x 10-19C)
An alpha particle can be deflected by electric and magnetic fields.
Mass
• An alpha particle has a mass of 4u.
1u is approximately the mass of a neutron or a proton.
( 1u is the mass of 1/12 of the mass of an atom of the isotope Carbon-12)
Nature
• An alpha particle consists of two protons and two neutrons.
This is the same as a nucleus of Helium-4 (42He).
Uses
• Alpha emitters (Americium-241) are used in smoke detectors.
Smoke particles absorb the Alpha particles and trigger the alarm.
The Mechanism of Alpha Decay
• When a nucleus emits an Alpha Particle
the proton number decreases by 2
the nucleon number decreases by 4.
Example - Americium-241
24195Am 23793Np + 42a
Beta-minus (b-) Radiation
Ionising Ability
• Beta-minus radiation causes much less ionization than alpha particles
Absorption - Range
• Because the Beta-minus particles cause less ionization, they are far more penetrating.
Beta-minus particles can travel through more than 30cm of air and through several millimetres of aluminium.
Electric Charge
• A Beta-minus particle carries negative charge.
Beta-minus particles carry the same charge as an electron, -1e.
A Beta-minus particle can be deflected by electric and magnetic fields.
Mass
• The mass of a Beta-minus particle is the same as the mass of an electron.
The mass of a Beta-minus particle is 1/1800 u.
Nature
• A Beta-minus particle is a very fast electron that has been emitted from the nucleus.
Uses
• Beta-emitters such as Strontium-90 are used to measure the thickness of paper and plastic sheets.
A Radioactive Isotope is placed above the paper and a detector below.
The amount of Beta particles passing through the paper depends upon the thickness of the paper.
The count rate can be used to control the pressure acting on rollers which change the thickness of the paper
The Mechanism of Beta-minus Decay
• A neutron in the nucleus changes into a proton and a very fast electron - the Beta-minus particle.
The Beta-minus particle is emitted.
The proton number increases by 1.
The nucleon number is unchanged
(The number of neutrons has decreased by 1).
Example - Strontium-90
9038Sr 9039Y + 0-1b-
Beta-plus (b+) Radiation
• Beta-plus decay occurs only rarely in Nature but does occur when certain man-made radiaoactive isotopes decay.
Absorption - Range
• As soon as a Beta-plus partcle encounters an electron, they undergo mutual annihilation and a Gamma photon is produced.
Since all atoms contain electrons, the Beta-plus particle will not get very far except in a vacuum.
Electric Charge
• The Beta plus particle is positively charged.
It carries a charge of +1e.
Mass
• The mass of a Beta-plus particle is the same as the mass of an electron.
The mass of a Beta-plus particle is 1/1800 u.
Nature
• A Beta-plus particle is a fast positron.
A positron is the anti-particle of an electron.
The Mechanism of Beta-plus Decay
• A proton in the nucleus changes into a neutron and the fast positron - the Beta-plus particle.
The Beta-plus particle is emitted.
The proton number decreases by 1.
The nucleon number is unchanged
( the number of neutrons has increased by 1).
Example - Carbon-11
116C 115B + 0+1b+
Gamma (g) Radiation
• After Alpha or Beta decay, a nucleus may be left in an excited energy state.
It can give out this energy in the form of electromagnetic radiation.
The photons emitted have a high energy and frequency.
They are called Gamma (g) Rays or Gamma Photons
Ionising Ability
• Gamma radiation causes only a small amount of ionisation.
Absorption - Range
• Because it interacts so little with matter, it is very penetrating.
The amount of Gamma Radiation is reduced by several centimetres of lead but it is not stopped.
Electric Charge
• None
Mass
• None
Nature
• High frequency, short wavelength electromagnetic radiation.
Uses
• Tracers in medicine and in industry.
• Treatment of cancer - Cobalt-60.
• Gamma sometimes follows on from Alpha or Beta Decay.
The proton number is unchanged
The nucleon number is unchanged
Summary
Property Alpha ( Beta-minus ( Beta-plus ( Gamma (
Charge +2e -1e +1e 0
Rest Mass 4u 1/1800 u 1/1800 u 0
Penetrating Ability 5cm of air, thin paper 30cm of air, few mm of Al Annihilated during interaction with electron A long way. Keeps going through lead.
Nature Helium nucleus fast electron positron electromagnetic radiation
Ionising Ability heavily light very light.
Stable Nuclei
• For stable nuclei with small Proton Numbers, the number of Protons is almost equal to the number of Neutrons.
• For stable nuclei with larger Proton Numbers there are more neutrons than protons.
• Most stable nuclei have an even number of protons and an even number of neutrons.
Two protons and two neutrons (a Helium Nucleus) form a particularly stable combination.
Unstable Nuclei
• Radioactive decay tends to produce nuclei which are nearer to the line of stability until a stable nucleus is formed.
• Nuclei above the line tend to be Beta-minus emitters.
• Nuclei below the line may be Beta-plus emitters.
• Nuclei with very large Proton Number tend to be Alpha emitters.
Radioactive Decay
Activity
• The number of disintegrations per second is known as the activity of the source.
Activity is measured in Becquerels (Bq).
1 Bq = 1 disintegration per second.
• This is not quite the same as count rate as measured using a Geiger-Muller Tube and Scaler because the G-M Tube does not detect a count every time a nucleus decays.
• It is not possible to predict when a a particular radioactive nucleus will decay.
• Because large numbers of nuclei are involved it is possible to apply statistics and so it is possible to state
the chance of a nucleus decaying in a certain length of time (usually 1 second).
the fraction of nuclei which will decay in a given length of time (usually 1 second).
An Experiment
• The number of counts per minute is recorded many times for a radioactive sample with a long Half-life.
• The number of times a particular value occurs (the frequency) can be plotted against the value for the count rate as a Histogram.
This sort of shape is typical for a Random Event
Throwing Dice - A Model of Radioactive Decay
• The fact that radioactive decay is a random event suggests that we should be able to model it using dice.
• When a die is thrown, the numbers 1-6 are all equally likely.
For the sake of the model, landing on a 6 represents the die "decaying".
• We cannot say when a particular die will land on a 6.
But we can say that the chance of a die landing on a 6 is 1/6.
and that if a large number of dice are thrown, 1/6 of them will land on a 6.
• Suppose a large number of dice were thrown over and over again.
The number of dice landing on a 6 each time could be counted.
A histogram of the number of times a particular value for the number of sixes occurred against the value could be plotted.
• The shape of the histogram would be the same as for the Histogram of Count-rate.
-------------------------
The Decay Equation
• The activity of a particular radioactive source depends upon just two factors.
the number of nuclei of that source present (N)
the radioactive isotope that is being measured.
Notice that it does NOT depend upon
Temperature, Pressure, Chemical Composition
or anything else.
• The activity is directly proportional to the number of nuclei present
activityN
This means that
activity = constant x N
The constant is called the decay constant and is represented by the symbol
activity = N
The Decay Constant
• The decay constant () has a different value for each radioactive isotope.
• The decay constant () has units second-1 (s-1).
• The decay constant () has two meanings.
It is the fraction of nuclei of an isotope decaying in 1 second.
It is the chance of a nucleus decaying in 1 second.
-------------------------
Exponential Decay
• Radioactive Decay is typical of a process where the rate of change of a quantity depends upon the value of that quantity.
Stage 1
• The sample starts with N0 radioactive nuclei.
The number decaying during the first interval of time (say 1 second) depends upon N.
The change in N (N) is given by
N = -N0
The number left is
N1 = N0 -N
Stage 2
• The number of radioactive nuclei at the beginning of the next interval of time is smaller.
Some of the nuclei have decayed.
The number of nuclei decaying will also be smaller
N = -N1
The number left is
N2 = N1 -N
and so on.
• This gives rise to a graph of Number of Nuclei against Time with a particular shape - an exponential graph.
• Because the Activity of a source is directly proportional to the Number of Radioactive nuclei (N), the graph of Activity against time will have exactly the same shape.
Constant Ratio Property of Exponential Curves
• One of the more useful properties of an Exponential Curve is that the ratio of the y-value at the beginning of a period of time to the y-value at the end of that period is the same for all of the curve.
Example
• For the graph above
When t = 0s, N0 = 1000
When t = 20s, N20 = 600
The ratio N20 / N0 = 600/1000 = 0.6
• This ratio will be the same for any two times which are 20 s apart.
And so N40 / N20 = 0.6
or
N40 = N20 x 0.6 = 600 x 0.6 = 360
Half-Life (t½)
• Half-Life is the time that it takes for half of the radioactive nuclei of an isotope to decay on average.
• It is also the time that it takes for the activity to fall to half of the original value.
• Different radioactive isotopes have different half-lives.
Isotope Half-life
Radon-222 4 days
Strontium-90 28 years
Radium-226 1602 years
Carbon-14 5600 years
Plutonium-239 24 400 years
Uranium-235 700 000 000 years
• For a given number of nuclei
a short half-life means a high count rate
a long half-life means a low count rate.
Example
The isotope Radon-222 is unstable and has a half-life of 4 days.
The particular sample of Radon-222 contains 640000 nuclei.
The initial count rate as measured using a Geiger-Muller Tube and a counter is 80 counts/min.
Time Number of Half-lives Number of Nuclei Fraction Remaining Count Rate
Days /min
0 1 640000 1 160
4 2 320000 1/2 80
8 3 160000 1/4 40
12 4 80000 1/8 20
16 5 40000 1/16 10
20 6 20000 1/32 5
Measuring Half-life
Correcting for Background
• When trying to find the half life from some real measurements due allowance has to be made for the background count rate.
• This can be done in one of two ways.
o The whole experiment can be carried out inside a lead box.
This will keep the value of the background count rate to a minimum but it will not be zero.
o The value of the background count rate must be measured and subtracted from each measurement of the count rate for the sample being studied.
Example
In this example the background count rate was measured without the sample being studied present.
Background count rate = 50 counts/minute
Time Count Rate Corrected Count Rate
minutes /minute /minute
0 1650 1600
2 1150 1100
4 850 800
6 600 550
8 450 400
10 325 275
12 250 200
14 187 137
Tuesday, October 7, 2008
Thursday, May 29, 2008
Group 4 – Physics Project
Group 4 Project.
Theme Alternative energy sources and waste management for sustainable AKA, M
Research question: Exploring the potential viability of meeting the school power demand through harnessing solar energy within the possible areas in AKA,M .
Type of research explorative, investigative, grounded
Methodology: Quantitative
Thought process (Guiding Questions)
What kind of data do we need?
- Electric consumption bills for the past couple of years
- Trends over the years
- Use school blueprints to get the area of the roof space
- Light intensity in the locality
- Weather Pattern in coastal region – average monthly sunlight levels – Kilindini
- The amount of light intensity to produce a Watt of energy
- Conversion rates with a variety of solar panels
How to collect the data?
- Electricity bills from school – ask finance department (documents) – Aziz/H.C
- School plans (Abraham/H.C/Ms. Clough) – or measure
- Light Intensity Experiment – cloudy day and sunny day/morning, noon, evening OR a Solar Card
- Weather Pattern from Internet or Metrological Center????
- Check specification of Solar Panel – from shop and internet
What instruments will we need?
- Solar Card/Light Meters
- Internal Assessment Experiment Instruments
- Measuring Tape
- Stationery, Calculator, Laptops, GDC
- Mobile Phone WITH CREDIT!!
- Uncensored Internet Connection – No Firewall to restrict downloads from sites for example email attachments
How will data be stored?
- Using Laptops and Paper
- Imaging Devices
How are we going to process/analyze the data?
- Tabulate the electricity bills and draw a trend graph, and find the mean/moving average over the years.
- Graph of potential kilowatts energy to provides in each area of school
- Make a map of school divided into sectors
- Get the average of the light intensities at different times of the day and different areas of the school which will be put on the map of the school.
- Average weather conditions over a period of time - table
Terms of Reference
All data collected goes to Secretary – Shailen & the nerve center – Levi
Duties
- Electric consumption bills for the past couple of years – LEVI (Thursday 29th May 2008)
- Use school blueprints to get the area of the roof space - LEVI (Thursday 29th May 2008)
- Light intensity in the locality – DIANA AND SHAILEN – (Friday 30th May 2008) by 10:45am
- Weather Pattern in coastal region – average monthly sunlight levels – Kilindini – AKSHAY (FRIDAY 11:00am)
- The amount of light intensity to produce a Watt of energy – SHAILEN (FRIDAY 11:00am)
- Conversion rates with a variety of solar panels - SHAILEN (FRIDAY 11:00am)
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