VIEWS: 28 PAGES: 16 POSTED ON: 5/8/2011
Curriculum interpretation “Wave Motion and Radioactivity and Nuclear Energy” YAU Wing-yee 12 April 2011 Wave Motion a. Nature and Point-to-note properties of waves nature of waves interpret wave motion in terms of oscillation realise waves as transmitting energy without transferring matter Huygen’s principle not required. wave motion and distinguish between transverse and longitudinal propagation waves •Phase differences describe wave motion in terms of waveform, deduced from crest, trough, compression, rarefaction, displacement-distance wavefront, phase, displacement, amplitude, graphs. period, frequency, wavelength and wave speed •Study phase difference present information on displacement-time and between two sinusoidal displacement-distance graphs for travelling waves (in phase and out waves of phase) •Transverse and determine factors affecting the speed of Longitudinal propagation of waves along stretched strings or springs •Direction of motion of wave particles. apply f = 1 / T and v = fλ to solve problems •Time lags and time leads in displacement-distance graph reflection realise the reflection of waves at a plane barrier/ and reflector/ surface Refraction Phase change at thin examine the condition for a phase change on film and air column reflection not required realise the refraction of waves across a plane Speed change of a boundary transverse wave across boundary examine the change in wave speeds during when it travels along refraction and define refractive index in terms of a string. wave speeds draw wavefront diagrams to show reflection and refraction Frequency measurement using stroboscope not required. Ripple tank can be used to demonstrate wave motion and properties. Video camera can be used in analysis of wave motion diffraction describe the diffraction of waves through a narrow and gap and around a corner interference examine the effect of the width of slit on the degree Qualitative of diffraction treatment only describe the superposition of two pulses realise the interference of waves Mathematical distinguish between constructive and destructive treatment of interferences superposition not examine the interference of waves from two required. coherent sources The concept of phase/ determine the conditions for constructive and path difference is destructive assumed in double interferences in terms of path difference slits interference. draw wavefront diagrams to show diffraction and Conversion between interference path difference and phase difference required only for in- phase and anti-phase interference problems. stationary wave explain the formation of a stationary wave (transverse waves only) describe the characteristics of stationary waves Problems on stationary longitudinal (sound) waves e.g. Kundt’s tube not required b. Light light in electromagnetic state that the speed of light and spectrum electromagnetic waves in a vacuum is 3.0 ×108 ms-1 state the range of wavelengths for visible light state the relative positions of visible light and other parts of the electromagnetic spectrum reflection of light state the laws of reflection Problem on general construct images formed by a plane mirror Snell’s law graphically refraction of light examine the laws of refraction sketch the path of a ray refracted at a Dispersion not required boundary Solve problem related to realize n = sini/sinr as the refractive index of refractive index of different a medium frequency of light. solve problems involving refraction at a Prism case. boundary examine the conditions for total internal total internal reflection reflection solve problems involving total internal Critical angle reflection at a boundary assumed construct images formed by converging and formation of images diverging lenses graphically by Graphical and numerical methods distinguish between real and virtual images lenses both assumed. to solve problems for a single thin lens apply 1/f=1/v+1/u (using the convention “REAL is positive”) Compound lens system (telescope, microscope; and Eye defects and correction not required. wave nature of light point out light as an example of transverse wave Problems on optical path difference e.g. air realise diffraction and interference as wedge/soap film/add thin evidences for the wave nature of light film to Young’s double slits setting/ immerse set examine the interference patterns in the up in water not assumed. Young’s double slit experiment Derivation not required but apply Δy = λD/ a to solve problems assumptions of Young’s equation is examine the interference patterns in the expected. plane transmission grating apply dsinθ = nλ to solve problems Diffraction grating for principal maxima only Effect of diffraction on double slits interference not required. Spectrometer setting not required. c. Sound wave nature of sound realise sound as an example of longitudinal Phase method/stationary waves wave method to measure speed of sound not realise that sound can exhibit reflection, required. refraction, diffraction and interference Effect of interference realise the need for a medium for sound in sound (change of transmission loudness) is assumed. compare the general properties of sound waves and those of light waves audible frequency range determine the audible frequency range examine the existence of ultrasound beyond the audible frequency range musical notes compare musical notes using pitch, loudness and quality Harmonics/ relate frequency and amplitude with the pitch and overtones not loudness of a note respectively required. ‘Quality’ interpreted as different waveforms. noise represent sound intensity level using the unit decibel discuss the effects Typical noise level in daily life is expected. of noise pollution and the Quantitative treatment notimportance of acoustic protection required. Definition of sound intensity level not required. Relationship between intensity level and amplitude not required. Curves of equal loudness not required. Radioactivity and Nuclear Energy (16 hours) a. Radiation and Point-to-note Radioactivity X-rays realise X-rays as ionizing electromagnetic radiations of short wavelengths with high penetrating power X-ray spectrum and realise the emission of X-rays when fast electrons hit a its detailed heavy metal target production mechanism discuss the uses of X-rays not required. α, β and γ describe the origin and nature of α, β and γ radiations radiations Qualitative compare α, β and γ radiations in terms of their treatment of penetrating power, ranges, ionizing power, behaviour penetration in electric field and magnetic field, and cloud chamber power tracks radioactive realise the occurrence of radioactive decay in decay unstable nuclides Use log graphs examine the random nature of radioactive decay state the proportional relationship between the to plot decay activity of a sample and the number of undecayed curve not nuclei required. define half-life as the period of time over which the number of radioactive nuclei decreases by a factor of Apply one-half exponential law determine the half-life of a radioisotope from its to solve decay graph or from numerical data problem. realise the existence of background radiation solve problems involving radioactive decay Derive represent the number of undecayed nuclei by the exponential law exponential law of decay N = Noe-kt using apply the exponential law of decay N = Noe-kt to solve problems proportional relate the decay constant and the half-life relation not required. Simple case of mixture of sources is expected. Detection of detect radiation with a photographic film and GM radiation counter detect radiation in terms of count rate using a GM counter Structure and operation principle of Familiarity with cloud chamber tracks ionization chamber/cloud assumed. chamber/GM coutner not required. radiation represent radiation equivalent dose using the unit sievert safety discuss potential hazards of ionizing radiation and the ways to minimise the radiation dose absorbed suggest safety precautions in handling radioactive sources Background radiation (sources and typical dose) assumed b. Atomic model atomic structure describe the structure of an atom define atomic number as the number of protons in the nucleus and mass number as the sum of the number of protons and neutrons in the nucleus of an atom use symbolic notations to represent nuclides isotopes define isotope and radioactive realise the existence of radioactive isotopes in transmutation some elements discuss uses of radioactive isotopes represent radioactive transmutations in α, β and γ decays using equations c. Nuclear energy nuclear fission and realise the release of energy in nuclear fission fusion and fusion Operation principle of nuclear power station, realise nuclear chain reaction structure of reactor, control rods, moderator not realise nuclear fusion as the source of solar required energy mass-energy state mass-energy relationship ΔE= Δm c2 relationship Mole, Avogadro’s number use atomic mass unit as a unit of energy and mass of a mole, atomic mass unit implied. determine the energy release in nuclear reactions Conversion of u, MeV and J expected. apply ΔE= Δm c2 to solve problems