# Physics

### Rationale/Aims

Physics is a fundamental science that endeavours to explain all the natural phenomena that occur in the universe. Its power lies in the use of a comparatively small number of assumptions, models, laws and theories to explain a wide range of phenomena, from the incredibly small to the incredibly large.

### Structure of Physics

In Physics, students develop their understanding of the core concepts, models and theories that describe, explain and predict physical phenomena.

### Links to Foundation to Year 10

The Physics curriculum continues to develop student understanding and skills from across the three strands of the F-10 Australian Curriculum: Science. In the Science Understanding strand, the Physics curriculum draws on knowledge and understanding from across the four sub-strands of Biological, Physical, Chemical and Earth and Space Sciences.

### Representation of Cross-curriculum priorities

While the significance of the cross-curriculum priorities for Physics varies, there are opportunities for teachers to select contexts that incorporate the key concepts from each priority.

## Unit 1: Thermal, nuclear and electrical physics

### Unit 1: Thermal, nuclear and electrical physics Description

An understanding of heating processes, nuclear reactions and electricity is essential to appreciate how global energy needs are met. In this unit, students explore the ways physics is used to describe, explain and predict the energy transfers and transformations that are pivotal to modern industrial societies. Students investigate heating processes, apply the nuclear model of the atom to investigate radioactivity, and learn how nuclear reactions convert mass into energy. They examine the movement of electrical charge in circuits and use this to analyse, explain and predict electrical phenomena.

Contexts that could be investigated in this unit include technologies related to nuclear, thermal, or geothermal energy, electrical energy production, large-scale power systems, radiopharmaceuticals and electricity in the home; and related areas of science such as nuclear fusion in stars and the Big Bang theory.

Through the investigation of appropriate contexts, students understand how applying scientific knowledge to the challenge of meeting world energy needs requires the international cooperation of multidisciplinary teams and relies on advances in ICT and other technologies. They explore how science knowledge is used to offer valid explanations and reliable predictions, and the ways in which it interacts with social, economic, cultural and ethical factors.

Students develop skills in interpreting, constructing and using a range of mathematical and symbolic representations to describe, explain and predict energy transfers and transformations in heating processes, nuclear reactions and electrical circuits. They develop their inquiry skills through primary and secondary investigations, including analysing heat transfer, heat capacity, radioactive decay and a range of simple electrical circuits.

### Unit 1: Thermal, nuclear and electrical physics Learning Outcomes

By the end of this unit, students:

• understand how the kinetic particle model and thermodynamics concepts describe and explain heating processes
• understand how the nuclear model of the atom explains radioactivity, fission, fusion and the properties of radioactive nuclides
• understand how charge is involved in the transfer and transformation of energy in electrical circuits
• understand how scientific models and theories have developed and are applied to improve existing, and develop new, technologies
• use science inquiry skills to design, conduct and analyse safe and effective investigations into heating processes, nuclear physics and electrical circuits, and to communicate methods and findings
• use algebraic and graphical representations to calculate, analyse and predict measurable quantities associated with heating processes, nuclear reactions and electrical circuits
• evaluate, with reference to empirical evidence, claims about heating processes, nuclear reactions and electrical technologies
• communicate physics understanding using qualitative and quantitative representations in appropriate modes and genres.

### Unit 1: Thermal, nuclear and electrical physics Content Descriptions

#### Science Inquiry Skills

Identify, research, construct and refine questions for investigation; propose hypotheses; and predict possible outcomes (ACSPH001)

Design investigations, including the procedure/s to be followed, the materials required, and the type and amount of primary and/or secondary data to be collected; conduct risk assessments; and consider research ethics (ACSPH002)

Conduct investigations, including using temperature, current and potential difference measuring devices, safely, competently and methodically for the collection of valid and reliable data (ACSPH003)

Represent data in meaningful and useful ways, including using appropriate Système Internationale (SI) units and symbols; organise and analyse data to identify trends, patterns and relationships; identify sources of random and systematic error and estimate their effect on measurement results; identify anomalous data and calculate the measurement discrepancy between experimental results and a currently accepted value, expressed as a percentage; and select, synthesise and use evidence to make and justify conclusions (ACSPH004)

Interpret a range of scientific and media texts, and evaluate processes, claims and conclusions by considering the quality of available evidence; and use reasoning to construct scientific arguments (ACSPH005)

Select, construct and use appropriate representations, including text and graphic representations of empirical and theoretical relationships, flow diagrams, nuclear equations and circuit diagrams, to communicate conceptual understanding, solve problems and make predictions (ACSPH006)

Select, use and interpret appropriate mathematical representations, including linear and non-linear graphs and algebraic relationships representing physical systems, to solve problems and make predictions (ACSPH007)

Communicate to specific audiences and for specific purposes using appropriate language, nomenclature, genres and modes, including scientific reports (ACSPH008)

#### Science as a Human Endeavour (Units 1 & 2)

Science is a global enterprise that relies on clear communication, international conventions, peer review and reproducibility (ACSPH009)

Development of complex models and/or theories often requires a wide range of evidence from multiple individuals and across disciplines (ACSPH010)

Advances in science understanding in one field can influence other areas of science, technology and engineering (ACSPH011)

The use of scientific knowledge is influenced by social, economic, cultural and ethical considerations (ACSPH012)

The use of scientific knowledge may have beneficial and/or harmful and/or unintended consequences (ACSPH013)

Scientific knowledge can enable scientists to offer valid explanations and make reliable predictions (ACSPH014)

Scientific knowledge can be used to develop and evaluate projected economic, social and environmental impacts and to design action for sustainability (ACSPH015)

#### Heating processes

Examples in context

Support materials only that illustrate some possible contexts for exploring Science as a Human Endeavour concepts in relation to Science Understanding content.

## Energy security and sustainability - emerging energy sources

The science of heating processes is of key importance to predicting future energy needs and the best mix of energy sources to meet these needs (ACSPH015). Sustainable energy production will require renewable energy sources that can be used alongside current power generation methods. Development of efficient and cost-effective methods for harnessing renewable energy sources such as solar and geothermal energy is dependent upon understanding of heating processes and energy transfers and transformations (ACSPH015). It has been difficult to predict future energy usage accurately. The complexity of the problem is compounded by factors including the emergence of new energy sources, improvements in the efficiency of existing energy sources, improved scientific understanding, changes in demand and social, economic and political pressures (ACSPH012).

## Energy balance of Earth

Circulation of energy in the atmosphere and oceans evens out solar heating imbalances on the planet’s surface, resulting in a more uniform temperature distribution. Increases in incoming or outgoing energy disturb Earth’s radiative equilibrium and affect global temperatures. Predictions of human-induced climate change and the possible effects of such change rely heavily on the science of heating processes (ACSPH014). Predictions are refined and improved as new data becomes available and scientific understanding improves, but the complexity and number of the assumptions involved prevents scientists from providing absolutely definite answers (ACSPH014). New technologies are being developed to address both the cause of human-induced climate change and the consequent effects on the natural and built environment (ACSPH011).

## Development of thermodynamics

The development of thermodynamic theory arose from a need to increase the efficiency of early steam engines, and led to important technological developments including the internal combustion engine, cryogenics and electricity generation. The development of the steam engine through the Savery and Watt engines led to important advances in the understanding of heat processes, energy transfer and transformation, and how heating can be used to do mechanical work (ACSPH010). Pioneers in this field, such as Joseph Black, Lavoisier and James Joule, produced quantitative, reproducible experiments that increased understanding of thermodynamics (ACSPH009). Other scientists, including Rankine, Kelvin, Maxwell and Gibbs, built further on this work, leading to the development of important laws and theories such as the gas laws, the laws of thermodynamics, and concepts such as heat capacity and latent heat (ACSPH010).

Mathematical representations and relationships

$$\mathrm Q=\mathrm m\mathrm c\operatorname\Delta\mathrm T$$

$$\mathrm Q=\;$$ heat transferred to or from the object,

$$\mathrm m=\;$$ mass of object, \mathrm c=\; specific heat capacity of the object,

$$\;\operatorname\Delta\mathrm T=\;$$ temperature change

$$\mathrm Q=\mathrm m\mathrm L$$

$$\mathrm Q=\;$$heat transferred to or from the object,

$$\mathrm L=\;$$ latent heat capacity of the material,

$$\mathrm m=\;$$ mass of object

$$\mathrm\eta\;=\;\frac{\mathrm e\mathrm n\mathrm e\mathrm r\mathrm g\mathrm y\;\mathrm o\mathrm u\mathrm t\mathrm p\mathrm u\mathrm t}{\mathrm e\mathrm n\mathrm e\mathrm r\mathrm g\mathrm y\;\mathrm i\mathrm n\mathrm p\mathrm u\mathrm t}\;\;\times\;\frac{100}1\%$$

$$\mathrm\eta=\;$$ efficiency

Heat transfer occurs between and within systems by conduction, convection and/or radiation (ACSPH016)

The kinetic particle model describes matter as consisting of particles in constant motion, except at absolute zero (ACSPH017)

All systems have thermal energy due to the motion of particles in the system (ACSPH018)

Temperature is a measure of the average kinetic energy of particles in a system (ACSPH019)

Provided a substance does not change state, its temperature change is proportional to the amount of energy added to or removed from the substance; the constant of proportionality describes the heat capacity of the substance (ACSPH020)

Change of state involves internal energy changes to form or break bonds between atoms or molecules; latent heat is the energy required to be added to or removed from a system to change the state of the system (ACSPH021)

Two systems in contact transfer energy between particles so that eventually the systems reach the same temperature; that is, they are in thermal equilibrium (ACSPH022)

A system with thermal energy has the capacity to do mechanical work (that is, to apply a force over a distance); when work is done, the internal energy of the system changes (ACSPH023)

Because energy is conserved, the change in internal energy of a system is equal to the energy added or removed by heating plus the work done on or by the system (ACSPH024)

Energy transfers and transformations in mechanical systems (for example, internal and external combustion engines, electric motors) always result in some heat loss to the environment, so that the usable energy is reduced and the system cannot be 100 percent efficient (ACSPH025)

#### Ionising radiation and nuclear reactions

Examples in context

Support materials only that illustrate some possible contexts for exploring Science as a Human Endeavour concepts in relation to Science Understanding content.

Radiometric dating of materials utilises a variety of methods depending on the age of the substances to be dated. The presence of natural radioisotopes in materials such as carbon, uranium, potassium and argon and knowledge about their half life and decay processes enables scientists to develop accurate geologic timescales and geologic history for particular regions (ACSPH011). This information is used to inform study of events such as earthquakes and volcanic eruptions, and helps scientists to predict their behaviour based on past events (ACSPH014). Dating of wood and carbon-based materials has also led to improvements in our understanding of more recent history through dating of preserved objects (ACSPH014).

## Harnessing nuclear power

Knowledge of the process of nuclear fission has led to the ability to use nuclear power as a possible long-term alternative to fossil fuel electricity generation (ACSPH013). Nuclear power has been used very successfully to produce energy in many countries but has also caused significant harmful consequences in a number of specific instances (ACSPH013). Analysis of health and environmental risks and weighing these against environmental and cost benefits is a scientific and political issue in Australia which has economic, cultural and ethical aspects (ACSPH012). The management of nuclear waste is based on knowledge of the behaviour of radiation. Current proposals for waste storage in Australia attempt to address the unintended harmful consequences of the use of radioactive substances (ACSPH013).

## Nuclear fusion in stars

Energy production in stars was attributed to gravity until knowledge of nuclear reactions enabled understanding of nuclear fusion. Almost all the energy used on Earth has its origin in the conversion of mass to energy that occurs when hydrogen nuclei fuse together to form helium in the core of the sun (ACSPH010). According to the Big Bang Theory, all the elements heavier than helium have been created by fusion in stars. The study of nuclear fusion in the sun has produced insights into the formation and life cycle of stars (ACSPH010). An unexpected consequence of early understanding of fusion in stars was its use to inform the development of thermonuclear weapons (ACSPH010). Research is ongoing into the use of fusion as an alternative power source (ACSPH013).

Mathematical representations and relationships

$$\mathrm N={\mathrm N}_\mathrm o\left(\frac12\right)^\mathrm n$$ (for whole numbers of half-lives only)

$$\mathrm N=\;$$ number of nuclides remaining in a sample, $$\mathrm n\;$$= number of whole half-lives,

$$\operatorname\Delta\mathrm E\;=\operatorname\Delta\mathrm m\mathrm c^2\;$$

$${\mathrm N}_\mathrm o=\;$$ original number of nuclides in the sample

$$\triangle\mathrm E=\;$$ energy change, $$\operatorname\Delta\mathrm m=\;$$ mass change, $$\mathrm c=\;$$ speed of light

$$\left(3\;\times10^8\;\text{m }\text{s}^{-1}\right)$$

The nuclear model of the atom describes the atom as consisting of an extremely small nucleus, which contains most of the atom’s mass and is made up of positively charged protons and uncharged neutrons surrounded by negatively charged electrons (ACSPH026)

Nuclear stability is the result of the strong nuclear force, which operates between nucleons over a very short distance and opposes the electrostatic repulsion between protons in the nucleus (ACSPH027)

Some nuclides are unstable and spontaneously decay, emitting alpha, beta and/or gamma radiation over time until they become stable nuclides (ACSPH028)

Each species of radionuclide has a specific half-life (ACSPH029)

Alpha, beta and gamma radiation have sufficient energy to ionise atoms (ACSPH030)

Einstein’s mass/energy relationship, which applies to all energy changes, enables the energy released in nuclear reactions to be determined from the mass change in the reaction (ACSPH031)

Alpha and beta decay are examples of spontaneous transmutation reactions, while artificial transmutation is a managed process that changes one nuclide into another (ACSPH032)

Neutron-induced nuclear fission is a reaction in which a heavy nuclide captures a neutron and then splits into two smaller radioactive nuclides, with the release of neutrons and energy (ACSPH033)

A fission chain reaction is a self-sustaining process that may be controlled to produce thermal energy, or uncontrolled to release energy explosively (ACSPH034)

Nuclear fusion is a reaction in which light nuclides combine to form a heavier nuclide, with the release of energy (ACSPH035)

More energy is released per nucleon in nuclear fusion than in nuclear fission because a greater percentage of the mass is transformed into energy (ACSPH036)

#### Electrical circuits

Examples in context

Support materials only that illustrate some possible contexts for exploring Science as a Human Endeavour concepts in relation to Science Understanding content.

## Electrical energy in the home

The supply of electricity to homes has had an enormous impact on society and the environment. An understanding of Kirchhoff’s circuit laws informs the design of circuits for effective and safe operation of lighting, power points, stoves and other household electrical devices (ACSPH015). Increases in the use of household electricity due to extreme weather in Australian summers and European winters creates problems in supply, causing brownouts, power failures and damage to household appliances (ACSPH015). Developing new household electrical devices, improving the efficiency of existing devices and ensuring consistency of electrical standards require international cooperation between scientists, engineers and manufacturers (ACSPH009).

## Powering the digital age

Computers, smartphones and the internet have changed the world, but none would be possible without a reliable supply of electricity. The first batteries, which enabled the investigation of current electricity, were developed by Alessandro Volta after a chance discovery by Luigi Galvani about the production of electricity (ACSPH010). Later, Michael Faraday developed the first electric generators and the ‘electrical age’ began. With the development of smartphones, tablets and similar devices that allow for constant communication and information flow, the design of long-lasting batteries to power these devices is an industry priority (ACSPH014). Long-lasting battery technology is also essential for safety devices like GPS locators, satellite phones and emergency beacons.

## Electric lighting

The introduction of electric lighting had a significant impact on society and the environment. The first efficient electric lamps were the filament lamps developed by Thomas Edison in the 1880s. Since that time, social, economic and cultural influences have led to development of a vast array of electric light sources including fluorescent lamps, halogen lamps, sodium lamps, light-emitting diodes and lasers (ACSPH012). Research and development of electric light sources has been underpinned by developments in our understanding of electricity, atomic physics and electromagnetism. Concerns about sustainable energy usage and global warming have led to international research and development to improve the energy efficiency of electric lighting (ACSPH015).

Mathematical representations and relationships

$$\mathrm I=\;\frac{\mathrm q}{\mathrm t}$$

$$\mathrm V=\frac{\mathrm W}{\mathrm q}$$

$$\mathrm R=\frac{\mathrm V}{\mathrm I}$$

$$\mathrm P=\frac{\mathrm W}{\mathrm t}=\mathrm V\mathrm I$$

Equivalent resistance for series components, $$\mathrm I=\;$$ constant

$${\mathrm V}_\mathrm t={\mathrm V}_1+{\mathrm V}_2+..{\mathrm V}_\mathrm n$$

$${\mathrm R}_\mathrm t={\mathrm R}_1+{\mathrm R}_2+..{\mathrm R}_\mathrm n$$

Equivalent resistance for parallel components, $$\mathrm V=$$ constant

$${\mathrm I}_\mathrm t={\mathrm I}_1+{\mathrm I}_2+..{\mathrm I}_\mathrm n\;$$

$$\frac1{{\mathrm R}_\mathrm t}=\frac1{{\mathrm R}_1}+\frac1{{\mathrm R}_2}+..\frac1{{\mathrm R}_\mathrm n}$$

$$\mathrm I=\;$$ current, V_subscript_t= total potential difference, $${\mathrm V}_\mathrm n$$ = the potential difference across each component, $${\mathrm R}_\mathrm t=\;$$ equivalent resistance, $${\mathrm R}_\mathrm n$$ = resistance of each component

$${\mathrm I}_\mathrm t={\mathrm I}_1+{\mathrm I}_2+..{\mathrm I}_\mathrm n\;$$

$$\mathrm V=$$ potential difference, $${\mathrm I}_\mathrm t=\;$$= total current, $${\mathrm I}_\mathrm n$$ = current in each of the components, $$\frac1{{\mathrm R}_\mathrm t}=\;$$ the reciprocal of the equivalent resistance, $$\;\frac1{{\mathrm R}_\mathrm n}=\;$$= the reciprocal of the resistance of each component

Electrical circuits enable electrical energy to be transferred efficiently over large distances and transformed into a range of other useful forms of energy including thermal and kinetic energy, and light. (ACSPH037)

Electric current is carried by discrete charge carriers; charge is conserved at all points in an electrical circuit (ACSPH038)

Energy is conserved in the energy transfers and transformations that occur in an electrical circuit (ACSPH039)

The energy available to charges moving in an electrical circuit is measured using electric potential difference, which is defined as the change in potential energy per unit charge between two defined points in the circuit (ACSPH040)

Energy is required to separate positive and negative charge carriers; charge separation produces an electrical potential difference that can be used to drive current in circuits (ACSPH041)

Power is the rate at which energy is transformed by a circuit component; power enables quantitative analysis of energy transformations in the circuit (ACSPH042)

Resistance for ohmic and non-ohmic components is defined as the ratio of potential difference across the component to the current in the component (ACSPH043)

Circuit analysis and design involve calculation of the potential difference across, the current in, and the power supplied to, components in series, parallel and series/parallel circuits (ACSPH044)