Where this unit fits in / Prior learning
This unit builds on:work on electricity and energy in unit 7I Energy resources, unit 7J Electrical circuits and unit 8I Heating and cooling. / To make good progress, pupils starting this unit need to:
  • know how to connect simple series and parallel circuits
  • recall that fossil fuels and wind, waves and the Sun are all energy resources
  • be familiar with the different ways in which energy is transferred and stored.

The concepts in this unit are:
voltage (potential difference), energy conservation, energy dissipation and energy efficiency.
This unit leads onto:
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.
Framework yearly teaching objectives - Energy
  • Recognise the idea of energy conservation as a useful scientific accounting system when energy is transferred; use this to explain energy transfers in familiar situations, energy efficiency and energy dissipation.
  • Develop, from a simple model of energy transfer in electrical circuits, the idea of potential difference in electrical circuits.
  • Use the model of energy conservation to explain how:
– the potential difference measured across cells or components shows how much energy is transferred from the cells to the current and from the current to the components;
–electrical energy can be generated using fuels, including the energy transfers involved; recognise possible environmental effects of this.
Expectations from the QCA Scheme of Work
At the end of this unit …
… most pupils will … / … some pupils will not have made so much progress and will … / … some pupils will have progressed further and will …
in terms of scientific enquiry NC Programme of Study Sc1 2c, g, j, k, m, o
  • 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.
/
  • measure the voltage of a range of cells
  • present data as charts or tables.
/
  • 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 processesNC Programme of Study Sc4 1a, b, c, 5a, c, e, g
  • describe some energy transfers and transformations in familiar situations, including dissipated energy, and energy transfer 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.
/
  • 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.
/
  • 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.

Suggested lesson allocation (see individual lesson planning guides)
Direct route
I1
Make it work / I2
Energy in and out / I3
Using electricity / I4
Power stations / Booster 6
Focus on energy – Making things happen
Extra lessons (not in Pupil book)
I2 Investigate:
How to increase the voltage in a fruit cell. / I4 Power stations Extra lesson for Activity I4b. / Review and assess progress (distributed appropriately)
Misconceptions
Pupils often think that current is used up around a circuit. This is because they confuse current with energy.
Health and safety (see activity notes to inform risk assessment)
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.

© Harcourt Education Ltd 2004 Catalyst 3

This worksheet may have been altered from the original on the CD-ROM.