science education teaching

Physics Program DRAFT Electrical Energy in the Home – Overview Topic: Electrical Energy in the Home Year: Preliminary Context: Modern life Preliminary Topic 1 PFA: History (P1), Nature & Practice (P2), Applications & Uses (P3) Knowledge: Kinetics & Dynamics (P6), Energy (P7) Values: P16 Electricity is an essential energy source for modern living. Disruption to supply or isolation can lead to the development of alternative methods of obtaining this essential energy resource. For electrical energy to be useful it must be harnessed through the use of an electrical circuit and an energy-converting appliance. As electricity became increasingly used as the main power supply in homes and electrical appliances became an integral part of daily life for many Australians, the dangers associated with electricity became more prominent. Voltages as low as 20 volts can be dangerous to the human body depending on the health of the person and length of time of contact with the current. Safety devices in household appliances and within the electric circuits in the home can prevent electrical injury or assist in reducing the potential for electric shock. Electrical Energy in the Home – Assumed Knowledge Preliminary Topic 1 • 5.6.3a design, construct and draw circuits containing a number of components. • 5.6.3b describe voltage, resistance and current using analogies • 5.6.3c describe qualitatively, the relationship between voltage, resistance and current RL, CH 16/07/2008 Physics Program DRAFT • 5.6.3d compare advantages and disadvantages of series and parallel circuits. RL, CH 16/07/2008 Physics Program DRAFT • Electrical Energy in the Home – Concept Map Preliminary Topic 1 Charge Static Electricit y Electric Fields Potential Differenc e AC/DC Currents Resistan ce Circuits Historical Developme nts Application s and Technolog y Househo ld Electricit Energy Consumptio n Safety RL, CH 16/07/2008 Physics Program DRAFT Electrical Energy in the Home – Outcomes Big Idea 1: Society depends on electricity • Preliminary Topic 1 discuss how the main sources of domestic energy have changed over time • identify data sources, gather, process and analyse secondary information about the differing views of Volta and Galvani about animal and chemical electricity and discuss whether their different views contributed to increased understanding of electricity • assess some of the impacts of changes in, and increased access to, sources of energy for a community • discuss some of the ways in which electricity can be provided in remote locations Big Idea 2: Electricity is easy to move around • describe the behaviour of electrostatic properties of the fields associated with them charges and the • • define the unit of electric charge as the coulomb define the electric field as a field of force with a field strength equal to the force per unit charge at that point: E = F q • present diagrammatic information to describe the electric field strength and direction: between charged parallel plates, about and between a positive and negative point charge RL, CH 16/07/2008 Physics Program DRAFT • solve problems and analyse information using: E = F q • define electric current as the rate at which charge flows (coulombs/ second or amperes) under the influence of an electric field • identify that current can be either direct with the net flow of charge carriers moving in one direction or alternating with the charge carriers moving backwards and forwards periodically • plan, choose equipment for and perform a first-hand investigation to gather data and use the available evidence to show the relationship between voltage across and current in a DC circuit • describe electric potential difference (voltage) between two points as the change in potential energy per unit charge moving from one point to the other (joules/coulomb or volts) • plan, choose equipment for and perform a first-hand investigation to gather data and use the available evidence to show the relationship between voltage across and current in a DC circuit • discuss how potential difference changes at different points around a DC circuit • • identify the difference between conductors and insulators define resistance as the ratio of voltage to current for a particular conductor: R = V I • plan, choose equipment for and perform a first-hand investigation to gather data and use the available evidence to show the variations in potential difference between different 16/07/2008 RL, CH Physics Program DRAFT points around a DC circuit • gather and process secondary information to identify materials that are commonly used as conductors to provide household electricity • describe qualitatively how each of the following affects the movement of electricity through a conductor: length, cross sectional area, temperature, material Big Idea 3: Series and parallel circuits are different • • identify the difference between series and parallel circuits compare parallel and series circuits in terms of voltage across components and current through them • plan, choose equipment or resources for and perform first-hand investigations to gather data and use available evidence to compare measurements of current and voltage in series and parallel circuits in computer simulations or hands-on equipment • • identify uses of ammeters and voltmeters explain why ammeters and voltmeters are connected differently in a circuit • explain why there are different circuits for lighting, heating and other appliances in a house • plan, choose equipment or resources and perform a first-hand investigation to construct simple model household circuits using electrical components RL, CH 16/07/2008 Physics Program DRAFT Big Idea 4: Power equals how quickly energy is transformed • explain that power is the rate at which energy is transformed from one form to another • identify the relationship between power, potential difference and current • identify that the total amount of energy used depends on the length of time the current is flowing and can be calculated using: Energy = VIt • perform a first-hand investigation, gather information and use available evidence to demonstrate the relationship between current, voltage and power for a model 6V to 12V electric heating coil • explain why the kilowatt-hour is used to measure electrical energy consumption rather than the joule • solve problems and analyse information using: P=VI, Energy = VIt RL, CH 16/07/2008 Physics Program DRAFT Big Idea 5: Magnetic fields are produced by currents • describe the behaviour of the magnetic poles of bar magnets when they are brought close together • define the direction of the magnetic field at a point as the direction of force on a very small north magnetic pole when placed at that point • • describe the magnetic field around pairs of magnetic poles describe the production of a magnetic field by an electric current in a straight current-carrying conductor and describe how the right hand grip rule can determine the direction of current and field lines • plan, choose equipment or resources for, and perform a firsthand investigation to build an electromagnet • perform a first-hand investigation to observe magnetic fields by mapping lines of force: around a bar magnet, surrounding a straight DC, current-carrying conductor, a solenoid, present information using ⊗ and • to show the direction of a current and direction of a magnetic field • compare the nature and generation of magnetic fields by solenoids and a bar magnet • identify data sources, gather, process and analyse information to explain one application of magnetic fields in household appliances Big Idea 6: Safety Devices are essential • discuss the dangers of an electric shock from both a 240 volt AC mains supply and various DC voltages, from appliances, on the muscles of the body • describe the functions of circuit breakers, fuses, earthing, double insulation and other safety devices in the home RL, CH 16/07/2008 Physics Program DRAFT Electrical Energy in the Home – Notes Preliminary Topic 1 .............................................................................................................................. ............................... .............................................................................................................................. ............................... .............................................................................................................................. ............................... 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RL, CH 16/07/2008