Module Organisation
Energy
Risks &
uncertainties vs.
beneficial uses
C 7: Radiation and Us
Students should learn Suggested learning and teaching activities 7.1 The electromagnetic spectrum
• A descriptive outline of the electromagnetic spectrum
• Approximate wavelength ranges of γ-rays, X-rays, ultraviolet, visible, infrared, microwaves, radio waves
• The wave nature of EM radiation
• Ways of representing EM radiation
• The relationship between frequency, wavelength and wave speed (c = fλ)
• Use a long spring to demonstrate the propagation, reflection and interference of waves
• Read about Maxwell’s formulation of the concept of electromagnetic waves
• Repeat Hertz’s experiment in sending a spark across a room
7.2 EM radiation as a carrier of energy
• EM radiation delivers energy in
‘packets’ called photons (energy = constant × frequency)
• Energy of a beam of EM radiation (number of photons × energy per photon)
• Intensity of radiation and its variation with distance from the source
• The flame test as an example for producing radiation of a particular frequency by atomic emission
• The reflection, absorption and transmission of EM radiation (e.g.
microwaves)
• Applications and risks of EM radiation as exemplified by UV radiation (e.g.
sterilisation, material identification, sun burns, photochemical smog)
• The benefits and risks of using EM radiation in everyday life
• Investigate the relationship between the size of the light patch on the wall and its distance from the source
• Perform a flame test of several metal salts
• Investigations on the reflection, absorption and transmission of microwaves
• Information search on the maintenance of ozone layer
• Case study of controversial issues related to the use of EM radiation (e.g.
Are mobile phones a health risk? Is the use of intensified pulsed light in beauty therapy safe? Are the claims of the therapeutic benefits of an infrared bed mattress trustworthy?)
7.3 Ionising radiations
• High energy EM radiation (e.g. high frequency UV, X-rays and γ-rays) can ionise atoms
• The three types of nuclear radiation: α, β and γ radiations
The origin and detection of nuclear
• History of the discovery of the ionising radiations
• Use of Geiger-Muller counters in investigating background radiation
• Experiment to compare the penetrating power of α, β and γ radiations
− Compare the penetrating power, range in air and ionising power of α, β and γ radiations
− eV as a unit of energy
7.4 The decay, half-life and uses of radioisotopes
• Random nature of decay
• Decay series
• Determining the half-life from a decay-curve
• Uses of radioisotopes: industrial, medical and dating
• Radiation safety
− Effects of α, β and γ radiations on us
− Background radiation
− The ALARA (as low as reasonably achievable) principle
− Radiation dose in sievert (Sv)
• Risk-benefit assessment on the diagnostic and therapeutic uses of radioisotopes
• Using coins and dice to model the decay of nuclei
• Investigation on indoor radon concentration and the factors which lead to an increase in concentration
• Information search on radioactive tracers and other uses of radioisotopes in medicine, agriculture, industry (e.g.
food irradiation and product sterilisation)
• Case study – benefits and risks related to diagnostic and therapeutic uses of radioisotopes
• Activity on calculating the risks and benefits for making an informed decision
• Information search on the use of film badges and TLD in monitoring dosages
• Information search on how a smoke detector works and what arrangements should be made for the disposal of a smoke detector.
7.5 Nuclear energy
• Fission and fusion reactions
• Nuclear energy generation: E = mc2
• Proper disposal of nuclear waste
• Watch a video on how Einstein came to the equation E = mc2
• Information search on nuclear accidents, e.g. the Chernobyl accident
• Compare the generation of electrical power using nuclear fission and the burning of fossil fuels
• Take a tour of a virtual nuclear reactor Module highlights
In this module, students have opportunities to:
• value the role and contribution of science in our understanding of phenomena involving EM radiation that are not directly observable
• appreciate the contribution of the applications of EM radiation in research, medical and industrial fields
• recognise that radioactive decay is an illustration that substances in Nature may experience spontaneous change
• recognise that the half-life of any particular isotope, being constant and unaffected by physical conditions, is useful for dating
• appreciate the ideas of conservation of matter and conservation of energy in studying radioactive decay
• appreciate that the theory E = mc2 , though developed from an intelligent ‘thought experience’ of Einstein, has established its rigour by experimental confirmation and its ability to make predictions about the interchange of mass and energy in a nuclear reactor
• develop an awareness of, and respect for, different points of view in society on controversial issues (e.g. generating electricity using nuclear energy)
• develop an ability to interpret and evaluate information presented in survey reports and media reports.
• develop the skills for making risk-benefit analysis in considering the use of radioactive decay in medical diagnosis and therapies, and in generating electricity
C 8 From Genes to Life
Overview Introduction
One major feature distinguishing living organisms from non-living things is the ability to pass genetic information from generation to generation. The inherited genetic information plays a critical role in controlling life phenomena.
In this module, students learn that DNA can replicate (make a copy of itself) before cell division so that genetic information can be passed to the next generation. The fundamental process of genetic information flow (i.e. from DNA to RNA then to proteins) is introduced.
An understanding of this process allows students to appreciate how proteins essential in different aspects of life processes are produced. A few genetic diseases are briefly discussed to show how defects in genetic information lead to congenital abnormalities.
The discoveries of DNA as the genetic material and of its double helix structure laid the cornerstone of genetics. In this module, students will appreciate these scientific endeavours by examining the work of great scientists and, in the process, realise that innovative interpretation of experimental data is one of the keys for great science. In addition, Mendel’s deduction of Laws of Inheritance is a good illustration of how scientists work – making hypotheses, verifying them through careful experimental design and analysis of experimental results, and drawing valid conclusions.
The development of gene technology has revolutionised our society. One of the aims of this module is to promote students’ understanding in gene technology so that they can evaluate its applications (e.g. genetic screening, cloning, production of genetically modified crops, and gene therapy).
Focusing Questions
• How did we come to know that DNA is the carrier of genetic information and how was its structure discovered?
• How does the structure of DNA enable it to serve as a carrier of genetic information and how do genes on the DNA control life phenomena?
• What is the significance of Mendel’s work and what contributed to his success?
• How does our knowledge of genes help us to understand the basis of biodiversity, evolution and genetic diseases?
• What are the applications of DNA technology? What are the ethical, economic and
Module Organisation