Doc Brown's Revision KS3 Science
PHYSICS Unit 9I Energy and electricity
What the Quiz is based on - original work schemes - programmes of study
All of KS3 Science is now under review
and the quizzes will be adapted to suit the NEW National Curriculum for KS3 Science
In this unit pupils:
• explore a range of useful energy transfers and transformations
• discuss the use of electricity as a convenient way to transfer energy to do useful things
• associate the concept of voltage with the transfer of energy in a circuit
• investigate the voltage of cells
• study how electricity is generated, with reference to environmental impacts
• use the principle of conservation of energy to identify ways in which energy is dissipated during transfers
In scientific enquiry pupils:
• use models to explain observations relating to electric currents
• use scientific knowledge to frame a question for investigation
• measure voltage in circuits
• identify patterns in the measurements of voltage in series circuits and use these to draw conclusions
Note on the teaching of energy
This unit presents a range of useful changes and helps pupils to use the language of energy transfer and transformation in describing them. The word ‘transfer’ is used to describe energy’s change of place; the word ‘transform’ is used to describe a change in the way energy shows itself, eg from electrical energy to light.
The unit focuses on how transfers and/or transformations of energy by electricity are important in everyday life. It explains these simply and looks at some of the consequences of the electricity supply industry. The unit covers the ideas of dissipation or ‘wasted’ energy and the conservation of energy. In extending the concept to these contexts, simplifications appropriate to year 9 pupils have been made.
Pupils need labels they can use when they come across energy, eg electrical energy, light and heat. This is a first step in developing understanding. Teachers should help pupils recognise that they need to go further in some contexts, eg that ‘spring energy’ is the result of the elastic properties of the metal the spring is made of, and so could be called ‘potential energy’ because of its compressed position. It would be inappropriate, at this stage, to develop this further and associate the energy with the electric bonding forces between the atoms of the spring. Formal definitions of work, kinetic energy and potential energy are also best left until key stage 4 for most pupils.
This unit is expected to take approximately 8 hours.
This unit builds on work on electricity and energy in units 7I ‘Energy resources’, 7J ‘Electrical circuits’ and 8I ‘Heating and cooling’. It relates to work on the reactivity of metals in unit 9F ‘Patterns of reactivity’ and work on fuels in unit 9G ‘Environmental chemistry’. It relates to unit 9D ‘Using control for electronic monitoring’ in the design and technology scheme of work, and to unit 18 ‘Twentieth-century conflicts’ and unit 20 ‘Twentieth-century medicine’ in the history scheme of work.
At the end of this unit
in terms of scientific enquiry
most pupils will: identify patterns in measurements of voltage and use these to draw conclusions about circuits; identify and control key factors in investigating simple cells and identify patterns in their results, including observations that do not fit the main trends
some pupils will not have made so much progress and will: measure the voltage of a range of cells; present data as charts or tables
some pupils will have progressed further and will: relate energy transfer devices in the laboratory to everyday appliances; synthesise information from secondary sources about the development of the electricity supply industry and communicate it clearly; consider whether data is sufficient, and account for anomalies
in terms of physical processes
most pupils will: describe some energy transfers and transformations in familiar situations, including dissipated energy, and devices; recognise that the voltage change across a circuit component is a measure of its energy transfer; describe how voltage originates from a chemical cell; give examples of the hazards of high-voltage circuits; compare the energy consumption of common electrical appliances; describe how electricity is generated by energy from fuels, and recognise possible environmental effects of this
some pupils will not have made so much progress and will: describe some useful energy transfer devices; recognise that any functioning circuit needs a power supply to provide a voltage and that high voltages are hazardous; recognise that electricity is a convenient way of ‘delivering’ energy, but that it must be paid for and that its generation can cause environmental problems; give examples of how energy goes to waste
some pupils will have progressed further and will: apply a model of voltage and energy changes to a circuit; recognise that although the total energy in a system is conserved, energy can be dissipated; use ‘power ratings’ in comparing the costs of using different electrical appliances; link the function of an electric generator to magnetic effects
It is helpful if pupils:
• know how to connect simple series and parallel circuits
• recall that fossil fuels and wind, waves and the Sun are all energy resources
Risk assessments are required for any hazardous activity. In this unit pupils:
• use mains electrical equipment in their investigations
Pupils must not experiment with mains electricity.
Model risk assessments used by most employers for normal science activities can be found in the publications listed in the Teacher’s guide. Teachers need to follow these as indicated in the guidance notes for the activities, and consider what modifications are needed for classroom situations.
Through the activities in this unit pupils will be able to understand, use and spell correctly:
• words and phrases relating to scientific enquiry, eg independent and dependent variable, control
• words and
phrases describing energy transfers and transformations,
• words and phrases relating to energy supply and waste, eg conservation, dissipation, electric generator, dynamo, power station
Through the activities pupils could:
• use secondary sources to assess conflicting evidence and arrive at a considered viewpoint
• write coherent text to communicate information effectively
• a selection of electrical toys and devices to show energy transfers and transformations
• samples of fruit and vegetables or dilute acid solutions
• a selection of samples of metals to make electrodes, eg copper, zinc, iron, aluminium, magnesium
• secondary source material on generating electricity and associated environmental issues, electric cars and other ‘energy-saving’ appliances
• small motors or materials to build generators
• a bicycle dynamo
• a joulemeter (and datalogger)
• ammeters and voltmeters or digital multimeters
• a household electricity meter or picture of one
• domestic appliances, including low-energy bulbs, or pictures of and energy information about these
• survey the power rating of various devices in the home or observe their electricity meter when different appliances are running
• check their own electricity bill
• keep a diary of energy experiences, eg Today I used my personal stereo with new batteries
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