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2 Electricity

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  1. Electricity units

    1. Use the following units: ampere (A), coulomb (C), joule (J), ohm (Ω), second (s), volt (V) and watt (W)

  2. (b) Mains electricity

    1. Understand how the use of insulation, double insulation, earthing, fuses and circuit breakers protects the device or user in a range of domestic appliances

    2. Understand why a current in a resistor results in the electrical transfer of energy and an increase in temperature, and how this can be used in a variety of domestic contexts

    3. Know and use power = current × voltage, P = IV, and apply it to selecting appropriate fuses.

    4. Use energy transferred = current × voltage × time, E = IVt.

    5. Know the difference between mains electricity being alternating current (a.c.) and direct current (d.c.) being supplied by a cell or battery

  3. (c) Energy and voltage in circuits

    1. Explain why a series or parallel circuit is more appropriate for particular applications, including domestic lighting

    2. Understand how the current in a series circuit depends on the applied voltage and the number and nature of other components

    3. Describe how current varies with voltage in wires, resistors, metal filament lamps and diodes, and how to investigate this experimentally

    4. Describe the qualitative effect of changing resistance on the current in a circuit

    5. Describe the qualitative variation of resistance of light-dependent resistors (LDRs) with illumination and thermistors with temperature

    6. Know that lamps and LEDs can be used to indicate the presence of a current in a circuit

    7. Know and use voltage = current × resistance, V = IR.

    8. Know that current is the rate of flow of charge

    9. Know and use charge = current × time, Q = It.

    10. Know that electric current in solid metallic conductors is a flow of negatively charged electrons

    11. Understand why current is conserved at a junction in a circuit

    12. Know that the voltage across two components connected in parallel is the same

    13. Calculate the currents, voltages and resistances of two resistive components connected in a series circuit

    14. Know that: • voltage is the energy transferred per unit charge passed • the volt is a joule per coulomb

    15. Know and use energy transferred = charge × voltage, E = QV.

  4. (d) Electric charge

    1. 2.22PConductors and insulators

      Identify common materials that are electrical conductors or insulators, including metals and plastics

    2. 2.23PCharging by friction practical

      Practical: investigate how insulating materials can be charged by friction

    3. 2.24PProducing electrostatic charge

      Explain how positive and negative electrostatic charges are produced on materials by the loss and gain of electrons

    4. 2.25PAttraction and repulsion

      Know that there are forces of attraction between unlike charges and forces of repulsion between like charges

    5. 2.26PElectrostatic phenomena

      Explain electrostatic phenomena in terms of the movement of electrons

    6. 2.27PElectrostatic dangers

      Explain the potential dangers of electrostatic charges, e.g. when fuelling aircraft and tankers

    7. 2.28PElectrostatic uses

      Explain some uses of electrostatic charges, e.g. in photocopiers and inkjet printers